1. What is back-end development
Back-end development refers to the development of server-based software applications, also known as the background or server-side programming of the system.
Backend programmers are responsible for handling the logic and functionality behind the scenes of a website or application, including database management, server-side scripting, API design, data security, website performance optimization, and more.
Back-end development techniques usually include knowledge of network protocols, server architecture, database management, programming languages and frameworks, and more. Programmers with excellent back-end development skills are able to create efficient, highly available, secure and well-scalable applications.
2. What is java back-end development
Java backend development refers to the development of web and enterprise applications using Java technology.
Java is a widely used programming language with good cross-platform compatibility and stability, so it is widely used in enterprise-level application development.
Java back-end development involves a variety of technologies and frameworks, such as Java Servlet, JSP, JavaServer Faces (JSF), Spring Framework, Hibernate ORM, MyBatis, etc. Java back-end development can implement a variety of functions, such as website development, e-commerce, financial systems, healthcare systems, and more. Java back-end developers need to have a solid Java language foundation, be familiar with development frameworks and tools, and have an in-depth understanding of databases, network programming, system architecture, and security.
3. Understand Java SE, Java EE and Java ME
3.1. Java SE (Java Standard Edition) is the standard version of the Java platform . It is the core part of Java development and provides basic functions and libraries of the Java language, such as Java collection framework, IO operations, concurrent programming, network programming, etc. Java SE is mainly used in the development of desktop applications, games, embedded devices, mobile applications, etc.
3.2. Java EE (Java Enterprise Edition) is the enterprise version of the Java platform . It is extended on the basis of Java SE and provides a series of APIs and tools for developing web applications, distributed applications and enterprise level applications. Java EE includes Java Servlet, JavaServer Pages (JSP), Enterprise JavaBeans (EJB), Java Persistence API (JPA) and many other technologies, so Java EE is suitable for developing enterprise-level applications, such as applications in banking and telecommunications.
3.3. Java ME (Java Micro Edition) is a miniature version of the Java platform , suitable for embedded devices with limited resources, such as mobile phones, TVs, smart homes, etc. Java ME provides a simplified version of the Java class library and virtual machine, enabling developers to develop applications that occupy less resources. The main technologies of Java ME include Java ME Connected Limited Device Configuration (CLDC) and Java ME Embedded Profile (MEEP), which provide an architecture and standard API for connecting limited devices.
四、Java Development Kit（JDK）
The Java Development Kit (JDK) is a software development kit used by Java developers.
It contains the Java runtime environment (JRE) and some development tools, such as compilers, debuggers, and performance analyzers.
JDK is the basic component necessary to develop Java applications, it provides all the tools and libraries required for Java development.
JDK includes various versions such as Java SE, Java EE, and Java ME, and each version is designed for different application scenarios and development requirements. The use of JDK can help Java developers quickly develop efficient, secure and reliable applications.
Five, the relationship between JDK, JRE and JVM
5.1. JDK (Java Development Kit) is a Java development kit , including JRE (Java Runtime Environment), compiler, debugger and other development tools. JDK is required to develop Java programs, which includes development tools such as JRE and Java class libraries.
5.2. JRE (Java Runtime Environment) is the Java runtime environment , including JVM (Java Virtual Machine) and Java class library and other components. JRE provides the environment necessary for the runtime of Java programs, but does not include development tools.
5.3. JVM (Java Virtual Machine) is a Java virtual machine , which is a software that can run Java programs on different operating systems. When running a Java program, the JVM converts Java bytecode into machine code for execution on a specific operating system. JVM realizes the cross-platform nature of Java programs, so that Java programs can run on any operating system that can run JVM.
The relationship and installation of JDK, JRE and JVM
Six, java common development tools
1. Eclipse : Eclipse is a free open source Java IDE with rich plug-ins and extension libraries, and supports multiple programming languages.
2. IntelliJ IDEA : IntelliJ IDEA is a commercial version of Java IDE, which has functions such as intelligent code editor, Java EE support, code refactoring, debugging and version control, and is widely used in Java development. My colleagues around me basically use this.
3. NetBeans : NetBeans is a free open source Java IDE that supports Java SE, Java EE and Java ME, and has functions such as visual Swing interface design, code debugging and code refactoring.
4. JDeveloper : JDeveloper is a commercial version of Java IDE, a tool developed and integrated for Oracle Corporation, supporting many Oracle products and technologies, such as Oracle Database, ADF and SOA.
5. Visual Studio Code : Visual Studio Code is a free open source code editor with rich plug-ins and extension libraries, and supports multiple programming languages, such as Java, C++, Python, and JavaScript. Although it is not specifically designed for Java development, it supports Java extensions and plug-ins and can be used for Java development.
These development tools have powerful functions and ease of use, and developers can choose appropriate tools according to their needs to improve development efficiency and quality.
7. What are the commonly used databases for java development/DataBase
7.1. Relational databases commonly used in Java development
7.1.1. Oracle : Oracle is the most widely used commercial database. It can run on multiple operating system platforms and use the JDBC driver to connect to Java applications.
7.1.2. MySQL : MySQL is a free and open source relational database. It runs on multiple operating systems and has the advantages of high performance, scalability and reliability. It is one of the most popular databases in Java development.
MySql-8.0.27-winx64 installation, super detailed_snow@li's blog-CSDN blog
7.1.3. SQL Server : SQL Server is a commercial database launched by Microsoft, which is suitable for Windows platform and .NET development environment, and provides powerful data management functions and high security.
7.1.4. PostgreSQL : PostgreSQL is a free open source relational database, which has high scalability, concurrency and security, and is commonly used in Java development.
7.2. Non-relational databases commonly used in Java development include
7.2.1. MongoDB : MongoDB is a free and open source, document-oriented database with high scalability, high performance, and flexibility. It is widely used in web applications, mobile applications, and the Internet of Things.
7.2.2. Redis : Redis is an in-memory database that supports multiple data structures, such as strings, hash tables, lists, sets, and ordered sets, and is widely used in distributed caching and real-time data processing scenarios. .
The above are commonly used databases in Java. Each database has its own characteristics and applicable scenarios. Developers can choose the appropriate database according to actual needs.
7.3 Difference between sqlserver and mysql
SQL Server and MySQL are two different relational database management systems, and they have the following differences:
7.3.1. Developers and usage scenarios : SQL Server is developed by Microsoft and is mainly used in large-scale enterprise systems, while MySQL is released by Oracle and is widely used in small and medium-sized enterprises and individuals.
7.3.2. License and cost : SQL Server is a commercial software that needs to purchase a license, which costs a lot, while MySQL can choose to use the open source version without paying for a license.
7.3.3. Database size and performance : SQL Server can handle larger databases, support more concurrent users and complex queries, but requires more computing resources, while MySQL is suitable for small and medium-sized applications and has higher performance and lower hardware requirements.
7.3.4. Data security : SQL Server provides more security functions, such as encryption, auditing and authentication, etc., while MySQL provides less security functions, but the security can be enhanced by using third-party tools.
7.3.5. Database management and maintenance : SQL Server provides more automatic management and maintenance functions, such as backup, recovery, performance monitoring and tuning, etc., while MySQL requires manual configuration and management.
To sum up, the main differences between SQL Server and MySQL lie in developers, usage scenarios, licenses and costs, database size and performance, data security, and database management and maintenance. Which database management system to choose depends on the needs of the application, budget, personnel skills, and other factors.
Eight, understand JDBC
JDBC is an acronym for Java Database Connectivity.
It is an API in the Java language for interacting with relational databases. It provides a set of classes and interfaces for executing SQL statements and processing results, and is part of the Java SE standard API.
JDBC enables Java applications to communicate with various databases, including Oracle, MySQL, SQL Server, etc., through standard interfaces.
Nine, JDBC usage steps
The answer comes from AI
9.1. Load the database driver : use the Class.forName() method or the DriverManager.registerDriver() method to load the JDBC driver so that a connection can be established with the database.
9.2. Establish database connection : use the DriverManager.getConnection() method to establish a connection with the database.
9.3. Create a Statement or PreparedStatement object : Create a Statement or PreparedStatement object for executing SQL statements through the createStatement() or prepareStatement() method of the Connection object.
9.4. Execute SQL statement : Use executeQuery() method of Statement or PreparedStatement object to execute SQL query statement, or executeUpdate() method to execute SQL update statement.
9.5. Processing the result set : Get the SQL query result set through the ResultSet object.
9.6. Close connections and related objects : After using JDBC related objects, you need to close ResultSet, Statement, PreparedStatement and Connection objects to release related resources.
Overall, JDBC provides reliable, portable data access, enabling Java applications to easily communicate and interact with a variety of databases.
10. Understand Maven / dependency management
Maven is a project object model (POM)-based build tool that automates building, testing, and deploying Java applications. Maven's dependency management is an important function of Maven. It can help us manage project dependencies and ensure that all required dependencies can be downloaded, configured and used correctly.
In Maven, dependencies refer to other Java class libraries or components that the current project depends on. When we declare a dependency in Maven's POM file, Maven will automatically find other dependencies required by the dependency, and automatically download them to the local repository (the default directory is `~/.m2/repository`) , for use during the build process.
Eleven, Maven's dependency management usually includes the following steps
11.1. Declare dependencies in the project's POM file : Maven uses coordinates (groupId, artifactId, and version) to specify dependencies in order to determine unique identifiers for dependencies.
11.2. Maven automatically downloads and installs dependencies : Maven will automatically download dependencies from the specified warehouse and install them into the local warehouse.
11.3. Version conflict resolution of dependencies : If multiple dependencies have different version requirements for the same class library, Maven will choose a solution to ensure that all projects can use the required version.
11.4. Inherit dependencies : dependencies can be inherited from the parent POM file of the project, which can simplify the POM files of sub-projects.
In short, Maven's dependency management can help us automatically manage project dependencies and ensure that all dependencies are downloaded and installed correctly. This can greatly simplify the construction and maintenance process of Java projects and improve development efficiency.
https://blog.csdn.net/snowball_li/article/details/129694337
12. Understand Tomcat in java
Tomcat is a web application server that implements Servlet and JavaServer Pages technologies, allowing Java developers to create dynamic web content and deploy it to a Tomcat server. Tomcat is an open source software developed and maintained by the Apache Software Foundation and can run on operating systems such as Windows, Linux, and Mac OS.
Java applications can run using Tomcat as an application server, which can process HTTP requests from clients and send responses to clients. At the same time, Tomcat also provides many functions, such as session management, security, Servlet container, etc. It also supports a variety of Web technologies, including Java Servlets, JavaServer Pages (JSP), Java EL, and WebSocket. Tomcat also supports integration with other web servers, such as IIS and Apache.
In short, Tomcat is a powerful, flexible, and scalable Web application server, and it is an important tool for Java developers to create and deploy Web applications.
JavaWeb (belonging to javaEE) project, now some may not need to configure tomcat, because the springboot framework of Java is used, which contains tomcat, most of the enterprise development needs to configure tomcat, so you can't do without it in the process of learning For tomcat, even if the front-end and back-end separation projects do not use tomcat to run jsp files, they must also use tomcat to run the back-end so that the back-end interface can be adjusted.
What does Tomcat do in Java? _Why Java needs tomcat_Technical Evangelist's Blog - CSDN Blog
Thirteen, understanding Spring in java
Spring is an open source framework for creating enterprise-level applications. It provides developers with many tools and features to help them build scalable, maintainable and efficient applications.
The Spring framework consists of multiple modules, including core container, AOP, data access/integration, Web, testing and security, etc. Among them, the core container is the most basic module, which provides features such as IoC (Inversion of Control) and DI (Dependency Injection), enabling developers to easily manage object dependencies in applications.
When using the Spring framework for development, we can hand over object creation and dependency management to the Spring container, making the application code more concise, easy to maintain, and scalable. At the same time, Spring also provides rich integration support, which can be integrated with various third-party frameworks and components, such as Hibernate, MyBatis, Struts, JSF, etc.
In general, the Spring framework is a very powerful and flexible framework, which can greatly improve the productivity and code quality of developers, and is one of the indispensable tools in the field of Java development.
14. Spring Boot
Spring Boot is a rapid development framework based on the Spring framework, and its goal is to simplify the development and deployment of Spring applications. Spring Boot enables developers to build a full-featured Spring application more quickly through automatic configuration and convention over configuration. It does not require developers to manually configure various cumbersome configuration files, but provides many preset configuration options to help developers quickly build an efficient, highly available, and scalable Spring application.
Spring Boot has built-in commonly used third-party libraries and components, such as Tomcat, MySQL, Redis, etc., and provides some convenient development tools and components, such as Spring Boot Starter, Spring Boot Actuator, Spring Boot DevTools, etc. Developers only need to use simple annotations to implement various functions, such as web development, data access, event processing, caching, security, etc., which greatly improves development efficiency.
In general, Spring Boot is a fast, lightweight, and convenient development framework that allows developers to build Spring applications faster, and provides a large number of functions and components to help developers solve various problems.
15. Spring MVC
Spring MVC is a sub-module in the Spring framework and a web framework based on the MVC (Model View Controller) design pattern. It can help us develop web applications more conveniently, and provides powerful functions and flexible configuration options.
In Spring MVC, the controller (Controller) receives the request and calls the code for business logic processing, the model (Model) is used to encapsulate the business data, and the view (View) is used to display the data. These three parts are developed separately, which makes the maintenance and expansion of the program easier.
Spring MVC provides an annotation-based configuration method, which greatly simplifies the configuration work of developers. For example, we can use the @RequestMapping annotation to specify which requests the controller handles, use the @RequestParam annotation to obtain request parameters, use the @ResponseBody annotation to specify the format of the response data, and so on. In addition, Spring MVC also provides a lot of built-in tag libraries and form tags, so that we can complete page development faster.
In general, Spring MVC is an excellent web framework that can help us develop web applications faster and easier, providing flexible configuration options and powerful functions.
Sixteen, Spring Cloud
Spring Cloud is a set of open source frameworks and toolsets based on the Spring framework for building cloud-native applications. It provides a series of out-of-the-box components that can help us quickly build and deploy distributed systems, and provides features required by common distributed systems, such as configuration management, service discovery, load balancing, routing, and fuse device, message bus, etc.
Based on the microservice architecture, Spring Cloud splits complex systems into multiple small services, each of which can be independently developed, tested, deployed, and expanded. Through service registration and discovery, we can easily manage the dependencies and call relationships between services; through service routing and load balancing, we can distribute requests to multiple service instances to improve system availability and performance; through fuses And current limiting, we can control the concurrency of services to ensure the stability of the system.
Spring Cloud provides multiple sub-projects, including service registration and discovery tool Eureka, load balancing component Ribbon, service fuse Hystrix, distributed configuration center Config, service gateway Zuul, message bus component Bus, etc. Developers can choose suitable sub-projects for integration and use according to actual needs to build highly available, high-performance, and highly scalable distributed applications.
Seventeen, the difference between Spring, SpringBoot, Spring MVC and SpringCloud in java
Spring is an open source framework for creating enterprise-level applications, including many modules, such as Spring Core, Spring MVC, Spring Data, etc. These modules provide a variety of functions, including IoC, AOP, data access, Web development, security, and more.
Spring Boot is a rapid development framework based on the Spring framework. Its goal is to simplify the development and deployment of Spring applications. Through automatic configuration and conventions greater than configuration, developers can build a full-featured Spring application faster. program. Spring Boot integrates many commonly used third-party libraries and components, such as Tomcat, MySQL, Redis, etc., and provides some convenient development tools and components, such as Spring Boot Starter, Spring Boot Actuator, Spring Boot DevTools, etc.
Spring MVC is a web development module in the Spring framework, which provides a web framework based on the MVC (Model-View-Controller) architecture for developing web applications. The Spring MVC framework provides many functions, such as request mapping, view parsing, data binding, data validation, exception handling, etc., making it easier and more efficient to develop web applications.
Spring Cloud is a distributed application development framework based on Spring Boot. It provides developers with a complete set of solutions, including service registration and discovery, configuration center, distributed tracking, etc. Spring Cloud allows developers to easily build highly available, high-performance, and scalable distributed applications.
In general, Spring is a large and comprehensive framework that provides a variety of functions. Spring Boot allows developers to build Spring applications more quickly. Spring MVC is a Web development module in the Spring framework. Spring Cloud is a framework and solution focused on distributed application development.
18. What does the Spring family bucket include?
18.1. Spring Framework: The Spring Framework is a Java-based enterprise-level application development framework for building web applications, RESTful APIs, and microservices.
18.2. Spring Boot: Spring Boot is a rapid development framework that allows developers to quickly build applications based on the Spring framework and automatically configure Spring and third-party libraries, thereby reducing the developer's configuration work.
18.3, Spring Cloud: Spring Cloud is a toolset for building distributed systems in the Spring family. Spring Cloud includes multiple sub-projects, such as Spring Cloud Config, Spring Cloud Netflix, etc., which can help developers build and manage distributed applications.
18.4, Spring Data: Spring Data is a set of tools used in the Spring framework to simplify database access. Spring Data provides a series of APIs that can help developers quickly build a data access layer.
18.5. Spring Security: Spring Security is a security framework for protecting web applications. Spring Security provides some common security features such as authentication, authorization, and password encryption.
18.6. Spring Integration: Spring Integration is a framework for building enterprise integration systems. Spring Integration provides some components, such as message channels, message processors and adapters, which can help developers build complex integration systems.
18.7, Spring Batch: Spring Batch is a framework for batch processing tasks. Spring Batch provides some tools that can help developers deal with large amounts of data, such as data import/export, data processing and data transformation, etc.
Nineteen, understand orm
ORM (Object Relational Mapping), that is, object-relational mapping, is to establish a mapping relationship between the data table in the relational database and the object in the object-oriented programming, so as to realize the persistence of the object in the program.
The ORM framework can convert Java objects into data in database tables, or convert data in database tables into Java objects, so that program developers can focus on business implementation without paying attention to underlying database operations.
Using the ORM framework can greatly improve development efficiency and program maintainability, and can also reduce the amount of program code and the probability of errors. ORM frameworks usually provide the following functions:
1. Definition of mapping relationship between objects and tables
2. Persistence and restoration of object state
3. Transaction management
4. Query language support
Common Java ORM frameworks include Hibernate, Mybatis, JPA, etc.
NestJS: Understanding ORM (Object Relational Mapping) - Snow@li's Blog - CSDN Blog
20. Mybatis
Mybatis is a lightweight, excellent persistence framework that supports custom SQL, stored procedures, and advanced mapping. Mybatis maps Java objects and SQL statements, and uses SQL statements to operate on the database. It can avoid performance problems in frameworks such as Hibernate, and at the same time, it will not make the code complicated and difficult to maintain.
The difference between Mybatis and other ORM frameworks is that it emphasizes the controllability and flexibility of SQL statements. SQL statements are defined by developers, and the mapping work of Mybatis is done by developers. This flexibility enables Mybatis to cope with various complex query requirements, and also provides a variety of mapping methods, including annotations and XML files.
The advantages of Mybatis mainly include:
1. Highly customizable: Mybatis allows developers to use custom SQL statements and stored procedures.
2. Excellent performance: Mybatis can improve performance through handwritten SQL and caching.
3. Simple and easy to use: Mybatis is easy to use and easy to learn, and the code is easy to maintain.
21. Nginx
Nginx is a high-performance web server that can also be used as a reverse proxy server, load balancer, HTTP cache and security protection, etc. It has become one of the most popular choices in web servers.
The advantages of Nginx mainly include:
1. High performance: Nginx adopts an event-driven, non-blocking IO model, which can handle a large number of connection requests while consuming relatively few system resources.
2. Scalability: Nginx's rich modular system and fast dynamic loading mechanism make it easy to expand its functions to meet the needs of different scenarios.
3. Reliability: The code design of Nginx is simple and reliable. It has many built-in security protection mechanisms, which can effectively resist various network attacks.
4. Ease of use: The configuration of Nginx is relatively simple, and it has very friendly documentation and community support, making it easy to use and maintain.
In Java development, Nginx is mainly used for load balancing and distributing requests to multiple back-end servers to improve system stability and performance. At the same time, Nginx can also be used to cache static resources, reduce the pressure on the server, and improve the speed of the website.
22. Redis
Redis is an open source, high-performance key-value store database that supports a variety of data structures, including strings, hash tables, lists, sets, and ordered sets. Features of Redis include:
1. High performance: Redis uses memory as the data storage medium, the data reading speed is very fast, and it supports a variety of efficient data structure operations.
2. Scalability: Redis provides a variety of fragmentation mechanisms, which can realize distributed storage and load balancing, and support horizontal expansion of data.
3. Persistence: Redis supports two persistence strategies: RDB snapshot and AOF log, which can ensure data persistence and security.
4. Publish/subscribe mechanism: Redis supports publish/subscribe mode, which can transfer messages between different clients.
In Java development, Redis is mainly used for caching, and some frequently accessed data is cached in Redis to improve system performance and response speed. At the same time, Redis can also be used to implement functions such as distributed locks, message queues, and counters. Redis's Java client library is very rich, and you can easily use various functions of Redis.
Twenty-three, Netty
Netty is a high-performance network framework based on NIO, and its core design idea is event-driven and asynchronous communication. It can help developers quickly and flexibly develop high-performance, high-reliability network applications.
In Netty, each network event is encapsulated into an event object, such as data received, connection established, connection disconnected, and so on. These events are handled by the thread pool provided by Netty, and the application is notified of the processing result through the callback function.
Netty provides rich codec and protocol support, can easily process data in various formats, and supports multiple protocols, such as HTTP, WebSocket, TCP, UDP, etc. At the same time, Netty also provides optimization technologies such as high-performance memory pool and zero copy, which can effectively reduce memory usage and CPU overhead, and improve application performance.
In general, by using Netty, developers can more easily build high-performance, high-reliability network applications, while reducing the complexity and difficulty of network programming.
24. Elastic Search
Elasticsearch is a distributed search and analysis engine based on the Lucene search engine, mainly used for full-text search, structured search and analysis. It is written in the Java language, can be deployed on any operating system that supports the Java virtual machine, and can handle large amounts of data.
Elasticsearch can quickly and accurately search large amounts of data and provide real-time search and analysis results. By indexing data, Elasticsearch can quickly locate and return relevant results, while also providing advanced search functions, such as fuzzy search, word suggestion and aggregation analysis. It also supports advanced search and filtering features such as full-text search, geo-location search, and language analysis.
Another key feature of Elasticsearch is that it is scalable and can be distributed across multiple nodes. This distributed architecture requires no additional coding by the user, allowing Elasticsearch to maintain high performance and reliability when processing massive amounts of data. In addition, Elasticsearch also provides an easy-to-use and powerful REST API and clients in multiple languages, enabling it to integrate with other technologies and communicate with other applications more easily.
In summary, Elasticsearch is a very powerful search engine that can help Java developers quickly build efficient search and analysis applications.
25. Logstash
Logstash is a very popular open source data collection engine that can collect data from various sources, including log files, system indicators, databases, network traffic, etc., and convert these data into a unified format, and finally output to the target system, such as Elasticsearch , Kibana, etc.
Logstash is mainly composed of the following three components:
1. Input: Responsible for collecting data from different sources, such as files, network traffic, system indicators, etc.
2. Filter: Responsible for converting and processing the input data, such as conversion from JSON to XML, date formatting, field deletion, field renaming, etc.
3. Output: Responsible for outputting the processed data to the target system, such as Elasticsearch, Kibana, etc.
Logstash not only supports a wide range of input and output plugins, but also supports various formats and protocols, such as JSON, XML, CSV, Syslog, etc. In addition, Logstash also provides a wealth of filter plug-ins, which can easily process different types of data.
The main advantages of Logstash are:
1. Support multiple data sources: Logstash can collect data from multiple data sources, including log files, databases, network traffic, etc.
2. Powerful filter function: Logstash provides a variety of filter functions, which can easily process different types of data.
3. Support multiple output formats: Logstash supports data output to multiple target systems, such as Elasticsearch, Kibana, etc.
4. Easy to use and deploy: Logstash has a very friendly user interface and is easy to use and deploy.
In short, Logstash is a very powerful data collection engine that can help Java developers easily collect, process and output various types of data.
26. RocketMQ
RocketMQ Official Website | RocketMQ
RocketMQ is an open source distributed message middleware developed by Alibaba Group. It supports high availability, high reliability, scalable and flexible message publishing and subscription models.
The architecture of RocketMQ mainly consists of the following components:
1. Nameserver: Responsible for maintaining topic and producer information and routing information.
2. Broker: Responsible for storing and distributing messages, supporting master-slave replication and database-level HA, and ensuring high reliability and availability of messages.
3. Producer: responsible for sending messages to the specified topic.
4. Consumer: Responsible for subscribing to the specified topic and receiving messages from the broker.
The main features of RocketMQ are:
1. High availability: RocketMQ adopts technologies such as master-slave replication and HA to ensure high availability of messages.
2. High reliability: RocketMQ supports mechanisms such as message persistence and retry to ensure that messages are not lost or repeated.
3. High performance: RocketMQ adopts zero-copy technology and efficient message sending mechanism to ensure low latency and high throughput of messages.
4. Scalability: RocketMQ adopts a distributed architecture, supports horizontal expansion, and can meet application requirements of various scales.
In short, RocketMQ is a powerful message middleware that has a wide range of applications in distributed systems. It can help Java developers build a reliable, high-performance, high-availability distributed message system, and realize reliable transmission and efficient processing of messages.
Twenty-seven, java single project (SSM)
A Java monolithic project refers to a Java application developed using the traditional monolithic architecture design pattern, which encapsulates all business logic and data access in the same application. The project usually consists of a main Java program, a series of Java classes and libraries. The advantages of Java monolithic project development are simple structure, easy maintenance and debugging, but when the scale of the application increases, there will be a problem that a single application cannot carry a large number of concurrent requests. Therefore, when developing large-scale projects, it may be more appropriate to adopt a distributed architecture or a microservice architecture.
Twenty-eight, java cluster project
The Java cluster project refers to a distributed system developed using the Java language, consisting of multiple computer nodes, each running the same application code, and working together to complete a task. Clustering can improve application reliability and performance, and enable horizontal scaling. Here are some common Java cluster projects:
1. Apache Hadoop: Distributed storage and computing framework for processing massive data sets.
2. Apache Spark: Distributed computing framework for in-memory computing and data analysis.
3. Apache Kafka: Distributed stream processing platform for real-time data processing and messaging.
4. Spring Cloud: Microservice framework for building distributed systems and containerized applications.
5. Apache Tomcat: Web server and Servlet container, suitable for high concurrent access and load balancing.
6. Zookeeper: Distributed coordination service, used to manage configuration and status information of distributed systems.
7. Elasticsearch: Distributed search and analysis engine for processing large-scale data sets and implementing full-text search.
8. Apache Cassandra: Distributed NoSQL database for high availability, high performance, and scalability.
9. Akka: A distributed computing framework that supports responsive programming and message-driven applications.
10. Hazelcast: Distributed memory data grid for caching and computing.
29. Can nginx load balancing be used to implement clustering in java projects?
Can. In Java projects, clustering can be implemented using the Nginx load balancer. Nginx can distribute requests to multiple Java application servers to improve system performance and availability. The specific steps are generally as follows:
1. Install and configure Nginx, set Nginx load balancing policies and rules, etc.;
2. Configure Java application servers, set their ports to different values, and ensure that they can all handle the same request;
3. In the Nginx configuration file The proxy forwarding rules of 2 point to different Java application server ports;
4. Start Nginx and Java application server.
In this way, when a user accesses a Java application, Nginx distributes the request to different Java application servers to achieve the effect of load balancing and clustering.
Thirty, understanding distributed in java projects
Distributed refers to the decomposition of a large system into multiple independent subsystems. These subsystems can run on different computers, servers or processes, and cooperate and coordinate through network communication to finally complete a common task.
In Java projects, distribution is reflected in the following aspects:
1. Distributed architecture: Common distributed architectures include client/server models, centralized architectures, N-tier architectures, and microservice architectures. The distributed architecture of Java projects is usually implemented using frameworks such as J2EE, Spring, and Spring Boot.
2. Distributed communication: In Java projects, distributed communication includes remote procedure call (RPC), message queue, RESTful API, etc. These techniques are used for communication between different processes or nodes.
3. Distributed storage: Distributed storage is usually used to store large amounts of data, including distributed file systems, distributed databases, and distributed caches.
4. Distributed transactions: Distributed transactions usually include more than two database operations, which need to ensure their atomicity, consistency, isolation and durability. In Java projects, a distributed transaction manager is usually used to handle distributed transactions.
5. Distributed deployment: The distributed deployment of Java projects can deploy different modules to different servers or nodes to achieve load balancing and high availability.
In conclusion, understanding and applying distributed technologies can make Java projects more efficient, reliable, and flexible.
Distributed (an algorithm of computer) - wikipedia
31. How to ensure the consistency of mysql and radius in the java project
In a Java project, if data consistency issues involving MySQL and Radius are involved, it can be achieved in the following ways:
1. Use the trigger function of MySQL to realize data synchronization at the MySQL database level. Defining triggers can monitor data changes in data tables in the MySQL database, and then automatically trigger some subsequent operations, such as sending data synchronization requests to the Radius server.
2. Use the transaction management mechanism in Java to realize data synchronization at the application level. In Java, you can use JDBC's built-in transaction management mechanism, or use the Spring transaction management framework to implement transactions. Through transaction control, data consistency between MySQL and Radius can be achieved.
3. Database two-way synchronization technology. You can use third-party tools or self-developed implementations to synchronize data between MySQL and Radius servers in two directions.
4. Use message middleware in Java projects, such as ActiveMQ or RabbitMQ, to realize asynchronous message communication between MySQL and Radius server. When data is updated in the MySQL database, a message can be sent to the message middleware, and then the message middleware will pass the message to the Radius server to realize synchronous data update.
It should be noted that the above methods all require real-time synchronization or asynchronous communication of data, and it is necessary to ensure data consistency during synchronization. At the same time, it is necessary to ensure that the network connection between MySQL and the Radius server is smooth, and to fully test and optimize the high concurrency situation.
Thirty-two, understanding front-end and back-end separation projects
The front-end and back-end separation project is a development model in which the development of the front-end and back-end are separated, and they use APIs to communicate. Front-end developers are responsible for building the user interface, and back-end developers are responsible for building the application's business logic and data storage. Using the development model of front-end and back-end separation can improve the flexibility and scalability of the project, because the front-end and back-end can be independently developed and deployed.
In a project where the front end and the back end are separated, different technology stacks can be used for the front end and the back end. The front-end usually uses JavaScript frameworks (such as React, Vue.js, Angular, etc.) to develop the user interface, and the back-end usually uses Java, Node.js and other programming languages to build the API and business logic of the application. The front end and the back end communicate through the RESTful API, the front end sends requests and receives responses, the back end processes business logic according to the requests, and returns the responses to the front end. The front end can use tools such as Axios and Fetch to communicate with the back end.
In projects where front-end and back-end are separated, front-end and back-end developers need to cooperate closely to ensure the consistency of API interface design and provide the necessary API documentation for the front-end. Additionally, automated testing can be used on the front-end and back-end to ensure the quality and stability of the system.
Thirty-three, postman
Postman is a tool for testing APIs that developers can use to quickly and efficiently test and debug API interfaces. Using Postman, you can create and send requests, check responses and results, and also simulate different HTTP requests, and set variables and environments to better manage test cases. `Postman` also provides many advanced features, such as automated testing, API documentation generation, and collaboration with teams, etc.
Thirty-four, DevOps
DevOps (collectively referred to as process, method and system) - Baidu Encyclopedia
DevOps is a software development methodology that integrates development and operations departments to enable continuous delivery and continuous deployment. It mainly emphasizes the close integration of the development team and the operation and maintenance team in the entire life cycle of software development to promote communication and collaboration, so as to deliver high-quality software faster.
In DevOps, software development and operations processes are viewed as a whole, where developers and operations staff share responsibility for fast delivery and high-quality output through streamlined testing, deployment, and management processes. Using tools and practices like continuous integration, continuous delivery, and automated testing can minimize human intervention, improve code quality, reduce deployment times, and make the software development process more predictable and repeatable.
Thirty-five, http
HTTP is the abbreviation of HyperText Transfer Protocol (Hypertext Transfer Protocol), which is an application layer protocol used to transfer data between web applications. HTTP works based on the client-server architecture model, where the client initiates a request and the server returns a response.
The HTTP protocol was originally used to transmit HTML documents between web browsers and web servers, but now HTTP has become one of the most important protocols on the Internet and is used to transmit various data, such as text, pictures, audio, Videos and other types of files.
The HTTP protocol is based on the TCP/IP protocol stack, uses TCP as the transmission protocol, and adopts the "request-response" mode. The client sends a request and the server returns a response. There are many versions of the HTTP protocol, such as HTTP/1.0, HTTP/1.1, HTTP/2, HTTP/3, etc., each version has different features and functions. Common HTTP request methods include GET, POST, PUT, DELETE, etc., and common HTTP response status codes include 200, 404, 500, etc.
Protocol: mastering the basic content of HTTP_snow@li's Blog-CSDN Blog
Thirty-six, git
Git is an open source distributed version control system, originally designed and developed by Linux developer Linus Torvalds in 2005, aiming to provide a more efficient, reliable and secure version management tool for the development of Linux kernel.
The main features of Git are distributed management, powerful branch management, efficient merge mechanism, secure transmission protocol, etc. Different from centralized version control, every developer of Git can have his own local warehouse, which can independently manage and version control the code. Git also supports multiple protocols, such as HTTP, SSH, etc., which can easily interact with remote warehouses.
Using Git for version management, developers can easily perform version management, branch management, merge, undo and other operations on the code without worrying about the loss or confusion of the code. Git's branch management function is particularly powerful. It can easily create, merge, and delete branches, realize independent development and testing of functions, and improve development efficiency and code quality.
At present, Git has become one of the widely used version control systems in the world, and is widely used in development projects of various sizes.
Git branch management and common commands_git branch commands_snow@li's blog-CSDN blog
Thirty-seven, jenkins
Jenkins is an open source continuous integration and continuous delivery (CI/CD) tool for automated building, testing, and deployment of software projects, helping development teams build, test, and deliver applications faster and more reliably.
Jenkins has a rich plug-in ecosystem that can be easily integrated with other tools and services, such as GitHub, GitLab, Jira, Slack, Docker, etc., and can be used for automated construction, automated testing, automated deployment, and automated monitoring.
The working principle of Jenkins is to listen to the changes of the version control system in the code base, such as Git, SVN, etc., and then automatically pull the latest code for construction, testing and deployment. Jenkins also supports multiple build environments and operating systems, making it easy to build and test projects in various languages and frameworks.
Using Jenkins can help the development team achieve fast, reliable, and repeatable construction and delivery, improve the efficiency and quality of software development, and promote collaboration and communication between development teams.
Thirty-eight, jira
Jira is a tool for agile project management, developed by the Australian company Atlassian. It is a cross-platform web application that can run on Windows, Linux and Mac OS X platforms.
Jira is mainly used for agile development and software development project management. It can help development teams with requirements management, task allocation, defect tracking, project planning and reporting, etc. In Jira, you can create, assign, and track issues, defects, and tasks, and customize workflows and task types according to your project needs.
Jira also supports various plug-ins and extensions, and can seamlessly integrate with other Atlassian tools, such as Confluence and Bitbucket, to improve the collaboration and productivity of the development team. It also supports apps on mobile devices, allowing users to access and manage projects anytime, anywhere.
Thirty-nine, Zen
`Zen Tao` is an open source project management software developed by the Chinese company Zen Tao Software Co., Ltd. It provides flexible project management, defect tracking, document management, team collaboration, test management and other functions to help users comprehensively manage software development and IT projects.
Zen features include:
1. Code management: ZenTao supports common version control systems, such as SVN, GIT, etc., and you can directly view the code in the software.
2. Task management: Users can create and assign tasks through ZenTao, assign them to each team member, and divide tasks into different priorities.
3. Defect management: ZenTao provides a complete defect management system, which can track and resolve software defects, including problem classification, severity, status, processor and other information.
4. Document management: ZenTao can manage and share files and documents, and supports common formats such as images, PDF, Word, and Excel.
5. Reporting and analysis: ZenTao provides a variety of reporting and analysis functions, which can help the team understand the real-time progress of the project.
Overall, ZenTao is a powerful project management software, especially suitable for small and medium-sized software development teams. In addition to offering a free version, it also offers an enterprise version for higher-level management needs.
Forty, confluence
Confluence is an enterprise-level document collaboration tool developed by the Australian software company Atlassian, which can help teams collaborate efficiently, create and share various types of documents.
Features of Confluence include:
1. Knowledge management: Confluence can store and manage various forms of information such as documents, data, text, and multimedia, and provides full-text search and tag functions so that users can find the information they need faster.
2. Integrated software: Confluence integrates with other Atlassian software (such as Jira, Bitbucket, etc.) and third-party software (such as Slack, Salesforce, etc.) to achieve seamless project management and team collaboration.
3. Easy collaboration: Confluence provides collaboration functions such as discussion, comment, and task assignment to facilitate team members to collaborate.
4. Customization: Confluence can be personalized by customizing themes, page layouts and plug-ins, so that users can customize the collaboration environment according to their needs.
In general, Confluence is a powerful document collaboration tool, suitable for various types of enterprises and teams, which can improve collaboration efficiency and increase the tacit understanding of teamwork.
Forty-one, Docker
Docker is an open source containerization platform that can package applications and their dependencies into a portable container so that applications can run in any environment without worrying about dependencies and configuration. It can greatly simplify application deployment and management.
Features of Docker include:
1. Lightweight: Docker containers are very lightweight, they only contain applications and their dependencies, not operating systems or virtual machine environments. This means that multiple containers can be run on the same host without taking up a lot of resources.
2. Portability: Docker containers are portable because they contain applications and their dependencies and can run on any platform that supports Docker without worrying about environmental differences.
3. Isolation: Docker uses the namespace and control group technology of the Linux kernel to isolate each container so that they can run simultaneously on the same host without interfering with each other.
4. Scalability: Docker supports automatic expansion, and containers can be easily added or removed to meet the needs of applications.
In general, Docker is a lightweight, portable and extensible containerization platform that can make application deployment and management more efficient and concise.
Forty-two, Kubernetes
Kubernetes is an open source container orchestration and management system that automates the deployment, scaling, and management of containerized applications. It provides a way to organize containers into a cluster, and also provides a way to manage containers in the cluster.
Kubernetes has the following characteristics:
1. Automated deployment and expansion: Kubernetes can automatically deploy and manage containers without manual intervention, and it can dynamically expand containers according to application load and resource requirements.
2. Fault tolerance: Kubernetes can automatically detect and repair container failures and node failures, and can also improve the availability of containers through multi-copy deployment.
3. Scalability: Kubernetes can manage large-scale container clusters, and nodes and containers can be easily added and removed to meet the needs of applications.
4. Cross-platform support: Kubernetes supports different container runtimes, including Docker and rkt, as well as multiple cloud platforms and deployment environments.
In general, Kubernetes is a powerful container orchestration and management system that can automatically deploy, expand, and manage containerized applications, making application management more efficient and concise.
Forty-three, Linux
Linux is a free and open source operating system developed based on the Unix operating system. It was developed by Linus Torvalds in 1991 and released in 1994. The biggest feature of Linux is its customizability and free nature.
The Linux operating system has the following characteristics:
1. Open source code: Linux is free software with open source code. Anyone can use, copy, modify and distribute it under the premise of complying with the GNU General Public License (GPL).
2. Multi-user and multi-task operation: Linux can support multiple users to use at the same time, and can also process multiple tasks at the same time.
3. Stable and reliable: The Linux operating system is stable and reliable, not easy to crash, and also has high security.
4. Powerful command line interface: Linux provides a powerful command line interface, which can control the system through the command line, and also supports the desktop environment.
5. Customizability: The Linux operating system can be customized according to the needs of different users, so as to meet the needs of different users.
Generally speaking, Linux is an open source operating system based on the Unix operating system, which has the characteristics of stability and reliability, multi-user multi-tasking, powerful command line interface and customizability. Linux is widely used in servers, cloud computing, mobile devices, and embedded devices, and it is also an important part of the field of computer science.
44. Business solution ability
1. Demand analysis and design capabilities: Java development requires an in-depth understanding of customer needs, conduct demand research and analysis, and be able to design efficient and reliable solutions and system architectures according to needs.
2. Coding ability: Java development requires good coding ability, proficient use of Java language and related technologies to develop high-quality software systems.
3. Database development ability: Java development needs to master database development technology, including knowledge of database design, SQL language and ORM framework.
4. Project management ability: Java development requires project management ability, be able to use project management tools proficiently, such as JIRA, Agile, etc., and be able to effectively manage project progress and quality.
5. Performance optimization ability: Java development needs to have performance optimization ability, and be able to use tools and technologies to perform performance analysis, tuning and optimization on the system.
6. Unit testing and integration testing capabilities: Java development requires unit testing and integration testing capabilities, and the ability to write test cases to ensure the quality and stability of the system.
7. Technology learning and innovation ability: Java development requires technology learning and innovation capabilities, and can continuously learn new technologies and new ideas, continue to innovate, and improve their own competitiveness.
8. Business process dismantling, business model analysis, informatization program preparation, business architecture design, etc.
45. Product Design Ability
1. Requirements analysis: be able to understand business requirements and translate them into specific functions and requirements.
2. Architecture design: be able to design a good system architecture, including selecting a suitable technology stack, and considering considerations such as scalability, maintainability, portability, and high availability. Integration of complex projects.
3. Database design: be able to design database structure, tables, views, indexes, etc., and have the ability to optimize query and performance.
4. API design: be able to design an API that is easy to use and maintain, and comply with the specifications of the RESTful API.
5. Front-end design: be able to design a user-friendly front-end interface with good interaction and responsiveness.
6. Security design: be able to design a secure system, including considerations of user authentication, authorization, data privacy, and network security.
7. Test design: be able to design effective test strategies and test cases to verify system functionality and quality.
8. Agile development: be able to use agile development methodology, quickly respond to changes, iteratively optimize products.
9. Business model design, etc.
46. Project management ability
1. Demand management ability: Understanding customer needs and grasping user needs is an important basis for Java development. Only by understanding the needs can the functions be realized accurately.
2. Plan management ability: be able to formulate reasonable plans according to project requirements, and master the allocation and management of time, cost, resources, etc.
3. Risk management ability: able to identify various risks in the project and eliminate or control them to reduce project risks.
4. Quality management ability: Ability to design and implement high-quality Java programs to ensure program stability, efficiency and reliability.
5. Communication management ability: be able to communicate well with customers, team members, and other relevant departments in order to better understand requirements and achieve project goals.
6. Team management ability: be able to lead and manage a team, help team members play their best potential, and ensure the successful realization of the project.
7. Change management ability: be able to master the skills of change management, effectively manage project changes, and ensure the stability and reliability of the project.
8. Project resource coordination ability, etc.
Forty-seven, how to learn java development well
1. Master the basic knowledge: In-depth study of the basic syntax, concept, operating system, database, etc. of Java, and master the development process of Java programs and its auxiliary tools.
2. Practical experience accumulation: In actual development, learn and master Java algorithms, design patterns, framework usage, Web development, multi-threading and other common technical points, and accumulate practical experience.
3. Learning other programming languages: Learning other programming languages also helps to expand one's thinking and programming skills, such as Nodejs, Python, C++, etc.
4. Read excellent code: Read the code written by other excellent developers, understand their coding style and practical experience, and learn from it.
5. Participating in open source projects: Participating in open source projects can exercise one's own development ability, understand other developers' coding and thinking methods, and also contribute to the community.
6. Continuously learn and update knowledge: Java development is a field that is constantly updated and developed. Master the latest technologies and trends, and continuously learn and expand skills.
Learning Java development well requires continuous learning and in-depth practice, as well as the accumulation of rich experience and knowledge.
Forty-eight, welcome to exchange and correct, pay attention to me, and learn together
reference link
Java Tutorial | Novice Tutorial
Java backend development environment_51CTO Blog
The first step of JAVA backend development: development environment configuration |