java注解

注解.jpg

简单实践

定义注解

import java.lang.annotation.*;
@Documented
@Target(ElementType.FIELD)
@Inherited
@Retention(RetentionPolicy.RUNTIME)
public @interface UserAnnotation {
  String name() default "test";

  enum Addrass{Beijing,Shanghang,shanxi};

  Class runtime() default Object.class;

}

注解使用

import annotation.an.UserAnnotation;

public class Entity {
    @UserAnnotation(name = "lalallala")
    private String test;

    public String getTest() {
        return test;
    }

    public void setTest(String test) {
        this.test = test;
    }
}

注解行为添加

import annotation.an.UserAnnotation;

import java.lang.reflect.Field;

public class Utils {
    public static void getEntityInfo(Class clazz) {
        Field[] fields = clazz.getDeclaredFields();
        for (Field field: fields) {
            if(field.isAnnotationPresent(UserAnnotation.class)){
                UserAnnotation d = (UserAnnotation) field.getAnnotation(UserAnnotation.class);
                System.out.println(d.name());
            }
        }
    }
}

测试

import annotation.Entity.Entity;
import annotation.Entity.Utils;

public class Test{
    public static void main(String []args){
        Utils.getEntityInfo(Entity.class);
    }
}