package com.bjsxt.test;

import java.lang.reflect.Method;

import com.bjsxt.test.bean.User;

/**

 * 通过跳过安全检查，提高反射效率

 * 三种执行方法的效率差异比较

 *

 * @author 尚学堂高淇 www.sxt.cn

 *

 */

public class Demo06 {

    public static void test01(){

        User u = new User();

        long startTime = System.currentTimeMillis();

        for (int i = 0; i < 1000000000L; i++) {

            u.getUname();

        }

        long endTime = System.currentTimeMillis();

        System.out.println("普通方法调用，执行10亿次，耗时："+(endTime-startTime)+"ms");

    }

    public static void test02() throws Exception{

        User u = new User();

        Class clazz = u.getClass();

        Method m = clazz.getDeclaredMethod("getUname", null);

//        m.setAccessible(true);

        long startTime = System.currentTimeMillis();

        for (int i = 0; i < 1000000000L; i++) {

            m.invoke(u, null);

        }

        long endTime = System.currentTimeMillis();

        System.out.println("反射动态方法调用，执行10亿次，耗时："+(endTime-startTime)+"ms");

    }

    public static void test03() throws Exception{

        User u = new User();

        Class clazz = u.getClass();

        Method m = clazz.getDeclaredMethod("getUname", null);

        m.setAccessible(true);    //不需要执行访问安全检查

        long startTime = System.currentTimeMillis();

        for (int i = 0; i < 1000000000L; i++) {

            m.invoke(u, null);

        }

        long endTime = System.currentTimeMillis();

        System.out.println("反射动态方法调用，跳过安全检查，执行10亿次，耗时："+(endTime-startTime)+"ms");

    }

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

        test01();

        test02();

        test03();

    }

}

package com.bjsxt.test;

import java.lang.reflect.Method;

import java.lang.reflect.ParameterizedType;

import java.lang.reflect.Type;

import java.util.List;

import java.util.Map;

import com.bjsxt.test.bean.User;

/**

 * 通过反射获取泛型信息

 * @author dell

 *

 */

public class Demo04 {

    public void test01(Map<String,User> map,List<User> list){

        System.out.println("Demo04.test01()");

    }

    public Map<Integer,User> test02(){

        System.out.println("Demo04.test02()");

        return null;

    }

    public static void main(String[] args) {

        try {

            //获得指定方法参数泛型信息

            Method m = Demo04.class.getMethod("test01", Map.class,List.class);

            Type[] t = m.getGenericParameterTypes();

            for (Type paramType : t) {

                System.out.println("#"+paramType);

                if(paramType instanceof ParameterizedType){//强制转换成泛型的参数类型

                    Type[] genericTypes = ((ParameterizedType) paramType).getActualTypeArguments();//获得真正的数据

                    for (Type genericType : genericTypes) {

                        System.out.println("泛型类型1："+genericType);

                    }

                }

            }

            //获得指定方法返回值泛型信息，参数的返回值只能1

            Method m2 = Demo04.class.getMethod("test02", null);

            Type returnType = m2.getGenericReturnType();

            if(returnType instanceof ParameterizedType){

                    Type[] genericTypes = ((ParameterizedType) returnType).getActualTypeArguments();

                    for (Type genericType : genericTypes) {

                        System.out.println("返回值，泛型类型："+genericType);

                    }

            }

        } catch (Exception e) {

            e.printStackTrace();

        }

    }

}