java自定义注解实例

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让例子说明一切！

类一：元注解，用于规定约束注解生命周期、行为等属性

package com.xujie.annotation;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
@Inherited
public @interface CustomFieldAnnotation {

public String address() default "china";
public int age() default 25;

}

类二：解析注解内容

package com.xujie.annotation;

import java.lang.reflect.Field;

public class ParseAnnotation {

public void parseAnnotation(Class myClass) throws Exception {

  Field[] fields=myClass.getDeclaredFields();
  for(int i=0;i<fields.length;i++)
  {
   CustomFieldAnnotation myfield = fields[i].getAnnotation(CustomFieldAnnotation.class);
   System.out.println("fields[i].getName():"+fields[i].getName());
   if(fields[i].getName().equals("address"))
   {
    System.out.println(myfield.address());
   }
   else if(fields[i].getName().equals("age"))
   {
    System.out.println(myfield.age());
   }
  }

}
}

类三：测试

package com.fujitsu.annotation;

public class TestAnnotation {

/**
* method annotation
*/

//use default value
@CustomFieldAnnotation(address="fujitsu")
private String address;

//use given value
@CustomFieldAnnotation(age=21)
private int age;

public static void main(String[]args)throws Exception
{
ParseAnnotation parse = new ParseAnnotation();
parse.parseAnnotation(TestAnnotation.class);
}
}