You should know whether your real goal of learning Java is clear and whether your idea of learning Java is mature. Many people may be dismissive of this problem. Based on the experience of most people who have been engaged in Java development for many years, I can finally learn the Java language well. Most people regard Java as their future goal. Once this goal is clear, they will give themselves endless motivation and pressure. Without motivation and pressure, people will have various excuses to retreat or even give up when they encounter difficulties. Secondly, after you have a very clear goal, and in the process of studying hard for it, you must understand the basic entry requirements of most enterprises for Java developers, and what common technologies you need to master. Of course, the requirements of different enterprises are different, but for a Java beginner, you should usually know that the following are the basic requirements of most enterprises for junior programmers. You can review your technical level from the following technical aspects.

First, any Java development direction must firmly grasp the basic core theoretical knowledge and practical technology of Java SE. From Java's point of view, no matter what kind of so-called advanced Java technology is based on the core of Java SE, such as Jsp dynamic web technology, Servlet Java EE standard core controller, freemarker template technology, or MVC pattern framework (Spring[ mainstream IOC container], Struts2), or ORM middleware mybatis, Hibernate and openjpa are both core technologies based on Java SE, among which the most important is Java object-oriented core programming design idea and implementation. That is, the three characteristics of Java object-oriented language (encapsulation, inheritance, polymorphism). If there is a big problem here, it will not be smooth to design coding in Java language and learn the following Java web and various spring mvc. Therefore, this place needs to make great efforts and spend more time learning and understanding this part and a lot of code practice. To attract students, there are many training institutions. It takes some time (even longer) for students to have a short sense of accomplishment, and it is almost unnecessary for you to make a graphical interface or a small game according to my years of work experience. Because this part of the content is almost useless in 99% Java development enterprises, there is no need to spend time learning it. Therefore, if a Java practitioner can't master the core theory and foundation of Java SE and skillfully use it, you will be blocked by the entry threshold of the enterprise at the first time. I have repeatedly stressed how important Java SE is. Once you learn Java SE well, it is very easy to learn anything in the future.

Second, the real enterprise Java project is 100% enterprise data processing, and it is an extremely important piece, because everything is recorded in the form of data in the computer, and the most basic and commonly used software device for permanently storing data is the database, so it is particularly important for the operation of the database. Experienced Java programmers even have a metaphor: "Grasping the core technology of Java SE is like a somersault cloud in the Monkey King, and having excellent database technology is like having a golden hoop", so you have the ability to make a big impact. If you are interested in searching information, PL/SQL database development languages are often ranked in the top 20, and many people have mastered PL/SQL and are looking for high-paying jobs everywhere. Of course, if you talk about database operation from the perspective of Java, you must thoroughly understand and master JDBC. Later, no matter what middleware you use similar to hibernate and MyBatison database operation, it is an encapsulation of JDBC. If you don't understand this, you can't pass the second entry threshold for enterprises.

Thirdly, when it comes to Java enterprise development, usually web applications, there is an unavoidable topic, that is, front-end development, which is naturally JS's specialty. In fact, there is a certain gap between this part and Java in logic and complexity, that is to say, some technologies are not difficult to master, but we must pay full attention to them, because it is a heavy task to apply JS or JS framework to build management interfaces and realize asynchronous data processing in Java web projects, especially in the background management of enterprise management systems. It is common to have one to two thousand lines of code in JS files. If it is data processing, JS framework is of course jQuery and related jQuery plug-ins, which cannot be ignored and must be mastered skillfully.

Fourth, the framework commonly used in enterprise Java projects, I personally think it is not difficult to master this part of the content and technical application. As long as you firmly master the core technology of Java, it is not difficult to learn on the basis of mastering JavaSE, database, Servlet and JSP. It is just a tool for building Java Web projects. The core thing to learn is the workflow and common comments of the framework, which will naturally be mastered slowly.