1. 先定義annotation

2. 使用annotation

例子：

import java.lang.annotation.*;

import java.lang.reflect.Method;

@Target(ElementType.METHOD)

@Retention(RetentionPolicy.RUNTIME)

@interface Test {

String info() default "";

}

class Annotated {

@Test(info = "AWESOME")

public void foo(String myParam) {

System.out.println("This is " + myParam);

}

}

class TestAnnotationParser {

public void parse(Class clazz) throws Exception {

Method[] methods = clazz.getMethods();

for (Method method : methods) {

if (method.isAnnotationPresent(Test.class)) {

Test test = method.getAnnotation(Test.class);

String info = test.info();

if ("AWESOME".equals(info)) {

System.out.println("info is awesome!");

// try to invoke the method with param

method.invoke(Annotated.class.newInstance(), info);

}

}

}

}

}

public class Demo {

public static void main(String[] args) throws Exception {

TestAnnotationParser parser = new TestAnnotationParser();

parser.parse(Annotated.class);

}

}程序輸出：

info is awesome!

This is AWESOME