java自定义注解实例

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);

}

}