Java friends who are already gearing up to work in a big factory, social recruitment needs more than 5 years, this year is particularly difficult:
- The number of employed people is as high as 8.74 million! Talent competition intensifies!
- The epidemic has reduced the recruitment needs of most companies! For social recruitment, the requirements for talent recruitment are getting higher and higher!
Not to mention the offer, it is very difficult to find a job now...
It is true that the economic situation this year is not good, but we have to figure out a reality, that is: it is not that companies are not recruiting people anymore, but they want to recruit talents with high professional ability!
Moreover, the epidemic has forced a large number of traditional industries to be interconnected, which also means that companies need more Internet talents, and the most scarce ones are excellent development engineers.
A few days ago, I saw on Boss Direct Employment that the salary of the Java development post has reached 20,000/month . The key is that Internet jobs have very little restrictions on majors, and the future development prospects and salary increase space are very large.
These data also show that it is the best time to enter the Internet industry as a development post.
Friends who haven't made an offer, take this opportunity to get ready! It’s just that the incomplete knowledge system and lack of project experience are common problems for many Java interviewers. If the technical strength is not enough, how can they get a good offer?
As the saying goes: "Reading thousands of books is not as good as traveling thousands of miles, and traveling thousands of miles is not as good as being guided by a famous teacher"! In order to solve the problem of difficult employment of contemporary Java interviewers, a set of Java core knowledge points is specially compiled. Covers a large number of knowledge points such as JVM, network, concurrency, distribution, Spring principles, microservices, Zookeeper, database, kafka, etc.
Since there are too many details and content, only some screenshots of knowledge points are roughly sorted out, and each small node that is sorted out has more detailed knowledge points. If you need this [Core Knowledge Notes] document, just private message [Learning] to get it~~~
Part of the content of Java core knowledge points notes
- Basic articles:
- concurrent articles
- Have you ever used Synchronized, what is its principle?
- You just mentioned acquiring a lock on an object, what exactly is this "lock"? How to determine the object's lock?
- What is reentrancy and why is it said; Synchronized is a reentrant lock?
- Does the JVM optimize Java's native organisms?
- Why is Sychronized an unfair lock?
- What are lock elimination and lock coarsening?
- Why is Schrorized a pessimistic thing?
- What is the implementation principle of optimistic locking? What is CAS, it has
- Is Optimistic Locking Good?
- How is the thread pool implemented in Java?
- Several core construction parameters for creating a thread pool?
- How are the threads in the thread pool created? Is it created with the start of the thread pool from the beginning?
- Since it is mentioned that different thread pools can be created by configuring different parameters, what are the default thread pools implemented in Java?
- How to submit threads in Java thread pool?
- network
- Network 7-layer architecture
- Principle of TCP/IP
- TCP three-way handshake/four-way wave
- Option: The most common optional field is the longest message size, also known as MSS (Maximum Segment Siz
- Data: The data part of a TCP segment is optional. When a connection is established and a connection is terminated, the message segments exchanged by both parties
- three handshake
- waved four times
- HTTP principle
- transfer process
- HTTP status
- HTTPS
- Principle of CDN
- Zookeeper
- What is ZooKeeper?
- What does ZooKeeper provide?
- Zookeeper file system
- Four types of znodes
- Zookeeper notification mechanism
- What does Zookeeper do?
- Zk's naming service (file system)
- Configuration management of zk (file system, notification mechanism)
- Zookeeper cluster management (file system, notification mechanism)
- Zookeeper distributed lock (file system, notification mechanism)
- The process of acquiring distributed locks
- Zookeeper queue management (file system, notification mechanism)
- Zookeeper data replication
- How Zookeeper works
- How does zookeeper ensure the sequential consistency of transactions?
- Server working status under Zookeeper
- How does zookeeper select the main leader?
- Zookeeper synchronization process
- Distributed notification and coordination
- Why is there a leader in the machine?
- How to deal with zk node downtime?
- The difference between zookeeper load balancing and nginx negative tailoring balancing
- zookeeper watch mechanism
- Kafka
- Kafka concepts
- Kafka data storage design
- producer design
- consumer design
- RabbitMQ
1. What is rabbitmq
2. Why use rabbitmq
3. Scenarios using rabbitmq
4. How to ensure that the message is sent to RabbitMQ correctly? How to ensure that the message receiver consumes the message?
5. How to avoid repeated posting or repeated consumption of rabbit messages?
6. What transmission is the message based on?
7. How to distribute the message?
8. How are messages routed?
9. How to ensure that messages are not lost?
10. What are the benefits of using RabbitMQ?
11. Rabbitmq cluster
12. Disadvantages of mq
- database
1. Please briefly describe the names of the four transaction isolation levels supported by InnoDB in MySQL, and the differences between them step by step?
2. What is the usage of ENUM in MySQL?
3. What is the difference between CHAR and VARCHAR?
4. What can be the string type of the column?
5. What storage engine is used in MySQL?
6. What does TIMESTAMP do on UPDATE CURRENT TIMESTAMP data type?
7. What is the difference between primary key and candidate key?
8. What are the methods and commands for MySQL database server performance analysis?
9. What is the difference between LIKE and REGEXP operations?
10. What is the difference between BLOB and TEXT?
11. Three paradigms of database?
12. How many TRIGGERS are allowed in a MySQL table?
13. What is a general SQL function?
14. What kinds of locks are there in MySQL?
15. MySQL data optimization.
16. MySQL keywords.
17. Storage engine.
18. Database backup.
19. The difference between truncate delete drop.
20. What is Redis? Summarize in two sentences.
21. Redis (pipeline, hash).
22. Redis implementation principle or mechanism.
23. Redis has two types of partitions.
24. What is MongoDB.
25. MongoDB features.
26. MongoDB functions.
- Principles of Spring
1. What is the Spring framework? What are the main modules of the Spring framework?
2. What are the benefits of using the Spring framework?
3. What is Inversion of Control (IOC)? What is Dependency Injection?
4. Please explain the loC in the Spring framework?
5. What is the difference between BeanFactory and ApplicationContext?
6. How many configuration methods does Spring have?
7. How to configure Spring with XML-based configuration?
8. How to configure Spring based on Java configuration?
9. How to configure Spring with annotations?
10. Please explain the life cycle of Spring Bean?
11. What is the difference between the scope of Spring Bean?
12. What are Spring inner beans?
13. Are singleton beans in the Spring framework thread-safe?
14. Please give an example of how to inject a Java Collection in Spring?
15. How to inject a Java.util.Properties into Spring Bean?
16. Please explain Spring Bean autowiring?
17. Please explain the difference between the automatic assembly mode?
18. How to enable annotation-based autowiring?
19. Please explain the @Required annotation with an example?
20. Please explain the @Autowired annotation with an example?
22. What is the difference between constructor injection and set value injection?
23. What are the different types of events in Spring framework?
24. What is the difference between FileSystemResource and ClassPathResource
25. What design patterns are used in the Spring framework?
- microservice
- cloud computing
If you need this [Core Knowledge Notes] document, just private message [Learning] to get it~~~