1.Core Java is the basics of Java and the class library of JDK. Many children will say, I understand JDK, but understanding is not enough. To know what is happening, you must also know why. The source code of JDK is written Very good. You should check it frequently. For frequently used classes, such as String, collection classes (List, Map, Set) and other data structures, you must know their implementation and what are the differences between different collection classes. Only then can you know how to use it on a specific occasion. Which collection class is more suitable and efficient to use? Just look at the source code for these contents
2. Multi-threaded concurrent programming, now concurrency is almost a necessary technology for writing server-side programs, so for Java You need to be familiar with multi-threading, including the object lock mechanism, the synchronized keyword, and the concurrent package. For this part, I recommend you read the book "Java Concurrent Programming Practice", which explains it in detail
3. I/O, Socket programming. First of all, you must be familiar with Socket programming in Java and the I/O package. The next step is Java NIO. The next step is the Socket implementation at the bottom of the operating system. Understand how it is implemented in Windows and Linux. Socket
4. You don’t need to be familiar with some knowledge of JVM, but you need to understand it. This is the essence of Java, which can be said to be the mother body of Java. After understanding it, your horizons will be broader, such as the Java memory model (you will understand it) Understanding Java locks, multi-threading is helpful), bytecode, JVM models, various garbage collectors and choices, JVM execution parameters (optimizing JVM), etc. This knowledge is in the book "In-depth Java Virtual Machine" There are detailed explanations, or go to the Oracle website to check the specific version of the JVM specification.
5. Some commonly used design patterns, such as singletons, template methods, agents, adapters, etc., as well as in Core Java and The implementation of some specific scenarios in the Java framework may need to be accumulated slowly. First understand what usage scenarios there are. If you see them more, you will naturally use them.
6. Commonly used databases (Oracle, MySQL, etc.), SQL statements and general optimization
7. JavaWeb development frameworks, such as Spring, iBatis and other frameworks, the same principles are the most effective It is important to at least know their general principles.
8. Some other famous and widely used open source frameworks and packages, Netty network framework, Apache common's N multi-package, Google's Guava, etc. You can also often go to Github to find some codes. .
Macroscopically:
1. In terms of technical breadth
You must at least be proficient in multiple open source technologies, and have studied the source code of struts\spring, etc.
2. In terms of project experience
I have followed several large projects from beginning to end. The beginning refers to the demand stage, including demand research.
The tail refers to after the online delivery, including the maintenance phase.
3. In terms of architectural experience
Have experience in distributed system architecture and development. He has extensive experience in cross-system structural optimization and data storage performance indicators. Caching, vertical segmentation of databases, business abstraction and horizontal splitting, these should all be familiar to you.
4. In terms of industry fields
You must at least be proficient in one or two businesses. The so-called proficiency means that if you are in the financial securities business, you must be at least half a financial analyst. Those who are in the power business should at least be half a power engineer.
5. Personal cultivation
Have some unique insights of your own, and don’t follow what others say.
1. You need to be proficient in object-oriented analysis and design (OOA/OOD), involving patterns (GOF, J2EEDP) and comprehensive patterns. You should have a good understanding of UML, especially classes, objects, interactions and stated diagrams.
2. You need to learn the basics of the JAVA language and its core class libraries (collections, serialization, streams, networking, multithreading, reflection, event, handling, NIO, localization, and others).
3. You should understand JVM, classloaders, classreflect, and the basic working mechanism of garbage collection. You should be able to decompile a class file and understand some basic assembly instructions.
4. If you are going to write a client program, you need to learn WEB applets, and you must master the ideas and methods of GUI design, as well as SWING, AWT, and SWT of desktop programs. You should also have an understanding of the JAVABEAN component pattern for UI widgets. JAVABEANS is also used in JSP to separate business logic from the presentation layer.
5. You need to learn java database technology, such as JDBCAPI and be able to use at least one persistence/ORM architecture, such as Hibernate, JDO, CocoBase, TopLink, InsideLiberator (domestic JDO red factory software) or iBatis .
6. You should also understand the meaning of object-relational impedance mismatch, and how it affects the interaction between business objects and relational databases, and its operating results. You also need to master different Database product application, such as: oracle, mysql, mssqlserver.
7. You need to learn JAVA's sandbox security model (classloaders, bytecodeverification, managers, policies and permissions, codesigning, digitalsignatures, cryptography, certification, Kerberos, and others) and the different security/authentication APIs , such as JAAS (JavaAuthenticationandAuthorizationService), JCE (JavaCryptographyExtension), JSSE (JavaSecureSocketExtension), and JGSS (JavaGeneralSecurityService).
8. You need to learn Servlets, JSP, and JSTL (StandardTagLibraries) and optional third-party TagLibraries.
9. You need to be familiar with mainstream web frameworks, such as JSF, Struts, Tapestry, Cocoon, WebWork, and their underlying modes, such as MVC/MODEL2.
10. You need to learn how to use and manage WEB servers, such as tomcat, resin, Jrun, and know how to expand and maintain WEB programs based on them.
11. You need to learn distributed objects and remote APIs, such as RMI and RMI/IIOP.
12. You need to master various popular middleware technology standards and their implementation in combination with java, such as Tuxedo, CROBA, and of course javaEE itself.
13. You need to learn at least one XMLAPI, such as JAXP (JavaAPI for XMLProcessing), JDOM (JavaforXMLDocumentObjectModel), DOM4J, or JAXR (JavaAPIforXMLRegistries).
14. You should learn how to use JAVA API and tools to build WebService. For example, JAX-RPC (JavaAPI for XML/RPC), SAAJ (SOAPwithAttachmentsAPIforJava), JAXB (JavaArchitectureforXMLBinding), JAXM (JavaAPIforXMLMessaging), JAXR (JavaAPIforXMLRegistries), or JWSDP (JavaWebServicesDeveloperPack).
15. You need to learn a lightweight application framework, such as Spring, PicoContainer, Avalon, and their IoC/DI styles (setter, constructor, interfaceinjection).
16. You need to be familiar with different J2EE technologies, such as JNDI (JavaNamingandDirectoryInterface), JMS (JavaMessageService), JTA/JTS (JavaTransactionAPI/JavaTransactionService), JMX (JavaManagementeXtensions), and JavaMail.
17. You need to learn Enterprise JavaBeans (EJB) and their different component patterns: Stateless/StatefulSessionBeans, EntityBeans (including Bean-ManagedPersistence [BMP] or Container-ManagedPersistence [CMP] and its EJB-QL), or Message-DrivenBeans (MDB).
18. You need to learn how to manage and configure a J2EE application server, such as WebLogic, JBoss, etc., and take advantage of its additional services, such as clustering, connection pooling, and distributed processing support. You also need to understand how to package and configure applications on it and be able to monitor and tune its performance.
19. You need to be familiar with aspect-oriented programming and attribute-oriented programming (both of which are confusingly abbreviated as AOP), as well as their mainstream JAVA specifications and implementations. For example AspectJ and AspectWerkz.
20. You need to be familiar with different useful APIs and framework work to serve you. For example, Log4J (logging/tracing), Quartz (scheduling), JGroups (networkgroup communication), JCache (distributedcaching), Lucene (full-textsearch), JakartaCommons, etc.
21. If you are going to interface with or are working with an old system or local platform, you need to learn JNI (JavaNativeInterface) and JCA (JavaConnectorArchitecture).
22. You need to be familiar with JINI technology and its related distributed systems, such as mastering CROBA.
23. You need JavaCommunityProcess (JCP) and its different JavaSpecificationRequests (JSRs), such as Portlets (168), JOLAP (69), DataMiningAPI (73), etc.
24. You should be proficient in a JAVAIDE such as sunOne, netBeans, IntelliJIDEA or Eclipse. (Some people prefer VI or EMACS to write files. Whatever you use :)
25. JAVA (some configuration to be precise) is verbose and it requires a lot of manual coding ( EJB), so you need to be familiar with code generation tools such as XDoclet.
26. You need to be familiar with a unit testing system (JNunit) and learn different generation and deployment tools (Ant, Maven).
27. You need to be familiar with some software engineering processes that are often used in JAVA development. For example, RUP (Rational Unified Process) and Agile methods.
28. You need to be able to have an in-depth understanding and proficiency in operating and configuring different operating systems, such as GNU/linux, sunsolaris, macOS, etc., as a cross-platform software developer.
29. You also need to keep up with the pace of java development. For example, you can now learn javaME in depth, as well as the application of various new java specifications and technologies, such as the new web rich client technology.
30. You must know something about opensource, because at least many java technologies are directly driven by open source, such as java3D technology.
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