1. Basics
1.1, Java based
object-oriented features: inheritance, polymorphism and encapsulation
The difference between final, finally, finalize
What are the similarities and differences between Exception, Error, runtime exceptions and general exceptions
Please write 5 common runtime exceptions
What is the difference between int and Integer, the value cache range of Integer
Packaging, boxing and unboxing
String、StringBuilder、StringBuffer
The difference between overloading and rewriting
What is the difference between abstract class and interface
Talk about the use and realization of reflection
Talk about the scene and implementation of custom annotations
The difference between GET and POST for HTTP requests
The difference between Session and Cookie
List your commonly used JDK packages
MVC design ideas
The difference between equals and ==
The difference and connection between hashCode and equals methods
What is Java serialization and deserialization, and how to implement Java serialization? Or please explain the role of Serializable interface
Common methods in the Object class, why is wait notify placed in the Object?
How is the platform independence of Java reflected
The difference between JDK and JRE
What are the new features of Java 8
1.2, the
difference between Java common collection List and Set
The connection between Set and hashCode and equals method
The difference between List and Map
The difference between Arraylist and LinkedList
The difference between ArrayList and Vector
The difference between HashMap and Hashtable
The difference between HashSet and HashMap
The difference between HashMap and ConcurrentHashMap
The working principle and code implementation of HashMap, when to use red-black tree
The problem of HashMap infinite loop in multithreading
HashMap has the problem of Hash DOS attack
The working principle and code implementation of ConcurrentHashMap, how to count all the elements
Handwritten simple HashMap
Have seen the source code of those Java collection classes
1.3, process and thread
The concept of threads and processes, the concept of parallelism and concurrency
Method and realization of thread creation
Ways of communication between processes
Talk about the principle and difference of CountDownLatch and CyclicBarrier
Talk about the principle of Semaphore
Talk about Exchanger principle
Analysis of the principle of ThreadLocal, why OOM appears in ThreadLocal, and the underlying principle
Talk about the realization principle of thread pool
Several implementation methods of thread pool
The life cycle of the thread, how the state is transferred
Can refer to: "Java Multithreaded Programming Core Technology"
1.4, the lock mechanism
to talk about thread safety issues, what is thread-safe, how to ensure the security thread
The concept of re-entry lock, why re-entry lock can prevent deadlock
Four conditions for deadlock (mutual exclusion, request and hold, no deprivation, cyclic waiting)
How to check deadlock (check deadlock through jConsole)
Implementation principle of volatile (instruction rearrangement and memory refresh are prohibited)
Synchronized realization principle (object monitor)
The difference between synchronized and lock
AQS synchronization queue
The concept of CAS lock-free, optimistic lock and pessimistic lock
Common atomic operation classes
What is the ABA problem and how does the JDK solve the ABA problem?
Optimistic lock business scenarios and implementation methods
Common concurrency classes under Java 8 parallel package
The concept of bias lock, lightweight lock, heavyweight lock, and spin lock
Can refer to: "Java Multithreaded Programming Core Technology"
1.5, JVM
JVM runtime memory area division
Examples and causes of memory overflow OOM and stack overflow SOE, how to troubleshoot and solve
How to judge whether the object can be recycled or survived
Common GC recovery algorithms and their meaning
Common JVM performance monitoring and troubleshooting tools: jps, jstat, jmap, jinfo, jconsole, etc.
How to set parameters for JVM
JVM performance tuning
Class loader, parent delegation model, the life cycle of a class, how the class is loaded into the JVM
The process of class loading: loading, verification, preparation, analysis, initialization
Strong reference, soft reference, weak reference, phantom reference
Java Memory Model JMM
1.6, design patterns
common design patterns
The six principles of design patterns and their meaning
Common singleton mode and the advantages and disadvantages of various implementation methods, which one is best, handwriting common simple mode
Application of design patterns in actual scenarios
What design patterns are used in Spring
What design patterns are used in MyBatis
What design patterns are used in your project
Talk about the analysis of the use of design patterns in common open source frameworks
Dynamic agents are important! ! !
1.7, data structure
Tree (binary search tree, balanced binary tree, red-black tree, B tree, B+ tree)
Depth limited algorithm, breadth first algorithm
Kruskal's algorithm, Prin's algorithm, Diklas' algorithm
What is consistent Hash and its principle, Hash ring problem
Common sorting algorithms and search algorithms: fast sorting, binary search, heap sorting, etc.
1.8. Network/IO basic concepts of
BIO, NIO, AIO
What are long and short connections
What is the difference between Http1.0 and 2.0, please refer to "Http 2.0"
The basic concept of Https
Three handshake and four waved hands, why do you need to wave four times
What happens when the URL is entered from the browser to the page load? Refer to "What happened from entering the URL to page loading"
Two, data storage and message queue
2.1.
Precautions for using database MySQL index
What do DDL, DML, and DCL refer to
explain command
left join，right join，inner join
Database transaction ACID (atomicity, consistency, isolation, durability)
Isolation level of things (read uncommitted, read to commit, repeatable read, serializable read)
Dirty read, phantom read, non-repeatable read
Several paradigms of database
Common database commands
Talk about sub-library and sub-table design
Distributed dilemma brought by sub-database and sub-table and countermeasures (how to solve sub-database and sub-table under distributed, global table?)
Talk about SQL optimization
How to troubleshoot and solve the deadlock problem encountered by MySQL
The difference between storage engine InnoDB and MyISAM, advantages and disadvantages, usage scenarios
Index category (B+ tree index, full-text index, hash index), the principle of index
What is Adaptive Hash Index (AHI)
Why use B+tree as the data structure of MySQL index
The difference between clustered index and non-clustered index
Have you ever encountered an index failure, when may it occur, and how to solve it
How to solve limit 20000 loading is slow
How to choose a suitable distributed primary key scheme
Choose the right data storage solution
Several common distributed ID design schemes
Common database optimization solutions, how to optimize the database in your project
2.2.
What data types does Redis Redis have, please refer to "Detailed Explanation of 5 Common Redis Data Types"
Redis internal structure
Redis usage scenarios
Redis persistence mechanism, please refer to "Using Snapshot and AOF to Persist Redis Data to Hard Disk"
Redis cluster solution and implementation
Why is Redis single-threaded?
Cache avalanche, cache penetration, cache warm-up, cache update, cache degradation
The rationality of using cache
Redis common recycling strategy
2.3, Message Queuing
messages using queues scenes
Retransmission compensation solution ideas
Ideas for solving the idempotence of messages
Solutions to the accumulation of messages
How to implement message queue
How to ensure the orderliness of messages
Three, open source frameworks and containers
3.1, SSM/Servlet
Servlet life cycle
The difference between forwarding and redirection
What is the difference between BeanFactory and ApplicationContext
The life cycle of Spring Bean
How to implement Spring IOC
Scope of Bean in Spring, which one is the default
Talk about Spring AOP, Spring AOP implementation principle
Dynamic proxy (CGLib and JDK), advantages and disadvantages, performance comparison, how to choose
Spring transaction implementation, transaction propagation mechanism, default transaction category
The underlying principle of Spring transaction
Spring transaction failure (transaction nesting), JDK dynamic proxy pits Spring transactions, please refer to "JDK dynamic proxy pits Spring transactions!" 》
How to customize annotations to implement functions
Spring MVC running process
Spring MVC startup process
Spring's singleton implementation principle
What design patterns are used in the Spring framework
Spring other products (Srping Boot, Spring Cloud, Spring Secuirity, Spring Data, Spring AMQP, etc.)
Have you used Spring Boot? Understanding and principles of Spring Boot
The principle of MyBatis
Can refer to "Why is there Spring"
You can refer to "Why Spring AOP"
3.2
Why did Netty choose Netty
Talk about the usage scenarios of Netty in business
Native NIO has an epoll bug in JDK 1.7
What is TCP sticking/unpacking
TCP sticky/unpacking solution
Netty thread model
Talk about Netty's zero copy
Netty internal execution process
Netty reconnection implementation
3.3、Tomcat
Tomcat infrastructure (Server, Service, Connector, Container)
How to load servlet in Tomcat
Pipeline-Valve mechanism
You can refer to: "Four pictures show you the Tomcat system architecture!" 》
Four, distributed
4.1. Nginx
, please explain what is a C10K problem or do you know what a C10K problem is?
For an introduction to Nginx, please refer to "Introduction to Nginx"
Forward proxy and reverse proxy.
Several common load balancing strategies in Nginx
What are the Master and Worker processes on the Nginx server
What are the advantages of using a "reverse proxy server"?
4.2 Other distributed
to talk about the use of distributed business scenarios
Session distributed solution
Session distributed processing
Application scenarios of distributed locks, causes of distributed locks, basic concepts
Distribution is a common solution for locks
Common solutions for distributed transactions
Algorithm and implementation of cluster and load balancing
To talk about sub-database and sub-table design, please refer to "The specific implementation plan of database sub-table strategy"
Distributed dilemma brought by sub-database and sub-table and countermeasures
4.3、Dubbo
What is Dubbo, please refer to "Introduction to Dubbo"
What is RPC, how to implement RPC, and the implementation principle of RPC, please refer to "HTTP-based RPC Implementation"
What is the concept of SPI in Dubbo
The basic principle and execution process of Dubbo
Five, microservices
5.1, microservices
How is the front-end separation done?
Which frameworks for microservices
What are the common components of Spring Could? Refer to "Spring Cloud Overview"
Do you understand the domain driver? What is a domain-driven model? Congestion model, anemia model
Do you know JWT? What is JWT? Please refer to "JWT for Front-end Separation Tool"
How do you understand RESTful
Talk about how to design a good API
How to understand the idempotence of RESTful API
How to ensure the idempotence of the interface
Talk about CAP theorem, BASE theory
How to consider data consistency issues
Talk about the realization of eventual consistency
For the advantages and disadvantages of microservices, please refer to "Critique of Microservices"
The difference between microservices and SOA
How to split service, horizontal split, vertical split
How to deal with the chain call exception of microservices
How to quickly track and locate problems
How to ensure the security and authentication of microservices
5.2, security concerns
how to prevent common Web attacks, the way how SQL injection
Server communication security attack and defense
Analysis of HTTPS principle, downgrade attack, comparison of HTTP and HTTPS
5.3, performance optimization
performance indicators which
How to find performance bottlenecks
Common means of performance tuning
Talk about how you perform performance tuning in the project
Six, other
6.1, the design capacity
to talk about you've used in the project UML diagram
How do you consider componentization, serviceization, and system splitting
How to design the spike scene
Can refer to: "Summary of the technical challenges, coping strategies and architecture design of the spike system one or two! 》
6.2, traffic engineering
talk about your development process, how to automate deployment
How do you communicate with the team
How do you conduct a code review
Talk about your understanding of technology and business
Talk about the most difficult bug you encountered in the project and how to solve it
Introduce a project that you think is the most valuable in your work, as well as the role in the process, the problems solved, and what do you think your project has inadequate
6.3, soft power
to talk about your strengths and weaknesses, highlights
Tell me about what books you are reading recently, what blogs, what new technologies are you researching, and then look at the source code of those open source projects
Tell me about the most meaningful technical books you think
What to do after work, how to learn in normal times, how to improve one's abilities
Talk about thinking about personal development direction
Talk about what capabilities you think a server-side development engineer should have
Tell me what kind of architect you think and what the architect does
How to look at the problem of overtime
Of course, a complete interview is definitely more than the above-mentioned knowledge points, other things such as: Linux, data structures, algorithms, logical thinking questions, system design questions, career planning, etc. will be involved! In short, adequate preparation is the only magic weapon to deal with all interviews!
Welcome to leave a message to discuss the above issues! Any interview questions that are frequently asked are also welcome to leave a comment!