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Java-12 enumeration classes and annotations 1, Enum class (enum) 1. Use of enumeration class 1. Understanding of enumerating classes: there are only a limited number of objects in a class, which is uncertain. We call this class enumeration class 2. When you need to define a set of constants, it is strongly recommended to use enumeratio ...

preface Annotations are labels that are inserted into the source file. Javac will generate the same bytecode for the code with or without annotations. If you want to use annotations, you must provide annotation processing tools. These tools can process annotations at run time (reflection), at compile time (language model) or at bytecode le ...

Main knowledge points The servlet API gets the request parameters using request getParameter("xxx")In spring MVC, you only need to declare the parameter with the corresponding name in the processing method to automatically match the parameter passed in by the request and perform the corresponding type conversion (the servlet API also ...

catalogue 1, Annotation (also annotated) ■ comments and meta comments acting on the code: □ comments applied to the code: □ meta annotation (annotation applied to other annotations): □ highlight @ Retention and @ Target: ❀ important application of Annotation: using Annotation in reflection (1) Annotation on class name: (2) ...

Annotation overview What is annotation The most common annotations are those in the Spring framework, such as @ RequestMapping @Controller. What is the role of annotations? Why use annotations? Annotation is like a label, which can mark classes, attributes and methods. The marked content can use the getannotation (class < T >) method of t ...

Preface Spring Boot Common Annotations Tip: The following is the main body of this article. The following cases can be used as reference. 1. @SpringBootApplication          This note is the cornerstone of the Spring Boot project, which is added by default when creating the Application for the ...

What is annotation 👻 Annotation is a special "Annotation" placed in front of classes, methods, fields and parameters of Java source code. Some meta information attached to the code is used for parsing and using some tools during compilation and running, and plays the function of description and configuration. Annotations do no ...