On the application of custom annotation in spring

1. Java custom annotations and spring

As a kind of metadata information of program elements (classes, member variables, member methods, etc.), Java annotations will not affect the execution of the program itself. Special declarations can be added to program elements through custom annotations.

As a platform for building enterprise applications, spring provides rich functions. Combining Java custom annotations with spring to parse and process annotations in specific scenarios can reduce the coupling of applications and improve the scalability of programs.

2. Application scenarios

The following is a summary of several application scenarios and only the general idea (PS: not all scenarios have been practiced in the project)

2.1 login and permission interception

In web projects, login interception and permission interception are common functions. Through the user-defined login annotation or permission annotation, the annotation can be parsed in the user-defined interceptor to realize the interception function of login and permission.

This use mode has the advantages of simple configuration, high flexibility and low code coupling.

2.2 scheduled task management

In the process of system construction, there will be various requirements for scheduled tasks, and the centralized management of scheduled tasks can maintain the operation of the system more efficiently.

Through the custom scheduled task annotation in the repeating annotations section of the official JAVA annotation document, the scheduled task declaration of business methods can be realized. In combination with spring's container post processor, beanpostprocessor (PS: Spring container post processor, to be discussed in the next chapter), parse the user-defined annotation. After parsing the annotation information, use quartz API to build the runtime timing task, so as to complete the runtime creation and centralized management of the timing task.