1. 先定义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);
    }
}

程序输出：

info is awesome!

This is AWESOME

http://isagoksu.com/2009/development/java/creating-custom-annotations-and-
making-use-of-them/