Java-反射-性能消耗

川长思鸟来 2024-04-20 08:05 71阅读 0赞

代码：

package com.cdmt.java.annotation.historyhandler;
    
    import java.lang.reflect.InvocationTargetException;
    import java.lang.reflect.Method;
    
    /**
     * 反射性能消耗
     **/
    public class Test09 {
    
        public static void main(String[] args) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException {
           test1();
           test2();
           test3();
        }
        //正常调用方法
        public static void test1(){
            User user = new User();
            Long start = System.currentTimeMillis();
            for (int i = 0; i < 1000000000; i++) {
                user.getName();
            }
            Long end = System.currentTimeMillis();
            System.out.println("正常耗时" + (end - start) + " ms");
        }
        //反射调用方法
        public static void test2() throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
            User user = new User();
            Class<? extends User> c1 = user.getClass();
            Long start = System.currentTimeMillis();
            Method name = c1.getDeclaredMethod("getName", null);
            for(int i=0; i<1000000000; i++){
                name.invoke(user,null);
            }
            Long end = System.currentTimeMillis();
            System.out.println("正常耗时" + (end - start) + " ms");
        }
        //反射关闭检验调用方法
        public static void test3() throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
            User user = new User();
            Class<? extends User> c1 = user.getClass();
            Long start = System.currentTimeMillis();
            Method name = c1.getDeclaredMethod("getName", null);
            name.setAccessible(true);
            for(int i=0; i<1000000000; i++){
                name.invoke(user,null);
            }
            Long end = System.currentTimeMillis();
            System.out.println("正常耗时" + (end - start) + " ms");
        }
    }

结果：

![20190920101706953.png][]

[20190920101706953.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/18/c7bef0ffb9f44211b42f89fd0862a48b.png