java annotation

import java.lang.annotation.Documented;

import java.lang.annotation.ElementType;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.annotation.Target;

    /**

     * 定义作者信息，name和group

     * @author sprinng

     *

     */

    @Retention(RetentionPolicy.RUNTIME)

    @Target(ElementType.METHOD)

    @Documented

public @interface Author {

        String name();

        String group();

}

import java.lang.annotation.Documented;

import java.lang.annotation.ElementType;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.annotation.Target;

/**

 * @author sprinng

 *

 * 定义描述信息 value

 */

    @Retention(RetentionPolicy.RUNTIME)

    @Target(ElementType.TYPE)

    @Documented

public @interface Description {

        String value();

}

@Description(value = "这是一个有用的工具类")

public class Utility {

    @Author(name = "haoran_202",group="com.magc")

    public String work()

    {

        return "work over!";

    }

}

import java.lang.reflect.Method;

public class AnalysisAnnotation {

    /**

     * 在运行时分析处理annotation类型的信息

     */

    public static void main(String[] args) {

        try {

                //通过运行时反射API获得annotation信息

                Class<?> rt_class = Class.forName("com.demo.Utility");

                Method[] methods = rt_class.getMethods();

                boolean flag = rt_class.isAnnotationPresent(Description.class);

                if(flag)

                {

                    Description description = (Description)rt_class.getAnnotation(Description.class);

                    System.out.println("Utility's Description--->"+description.value());

                    for (Method method : methods) {

                        if(method.isAnnotationPresent(Author.class))

                        {

                            Author author = (Author)method.getAnnotation(Author.class);

                            System.out.println("Utility's Author--->"+author.name()+" from "+author.group());

                        }

                    }

                }

            } catch (ClassNotFoundException e) {

                e.printStackTrace();

            }

    }

}