Java 反射的性能问题

最近在了解反射优化的东西，做了一个 cglib,java 的反射 api 和直接调用的性能比较

public class SampleBean {
    public String echo(String name) {
        return name;
    }
}

测试代码：

        FastClass fastClass = FastClass.create(SampleBean.class);
        FastMethod fastMethod = fastClass.getMethod(SampleBean.class.getMethod("echo", String.class));
        SampleBean myBean = new SampleBean();
        long start = System.currentTimeMillis();
        for (int i = 0; i < 1000000; i++) {
            fastMethod.invoke(myBean, new Object[]{"haha"+i});
            //fastMethod.invoke(myBean, new Object[]{"haha"});
        }
        System.out.println("fastmethod:" + (System.currentTimeMillis() - start));
        
        start = System.currentTimeMillis();
        Method m = SampleBean.class.getMethod("echo", String.class);
        for (int i = 0; i < 1000000; i++) {
            m.invoke(myBean, "haha"+i);
            //m.invoke(myBean, "haha");
        }
        System.out.println("reflect:"+(System.currentTimeMillis() - start));
        
        start = System.currentTimeMillis();
        for (int i = 0; i < 1000000; i++) {
            myBean.echo("haha"+i);
            //myBean.echo("haha");
        }
        System.out.println("normal:"+(System.currentTimeMillis() - start));

输出： fastmethod:196 reflect:139 normal:72 上面一段代码如果跑被注释掉的那一行时间会更短： fastmethod:38 reflect:33 normal:25 个人猜测，百万次调用参数不变，是不是被优化了？

public class SampleBean {
    public String echo(String name, int age) {
        //改一下，方法稍微复杂点
        List<String> names = new ArrayList<>(100);
        for (int i = 0; i < 100; i++) {
            names.add(name+i);
        }
        List<Integer> ages = new ArrayList<>(100);
        for (int i = 0; i < 100; i++) {
            ages.add(age+i);
        }
        return name+"--"+age;
    }
}

测试代码：

FastClass fastClass = FastClass.create(SampleBean.class);
        FastMethod fastMethod = fastClass.getMethod(SampleBean.class.getMethod("echo", String.class, int.class));
        SampleBean myBean = new SampleBean();
        myBean.setValue("Hello cglib!");
        long start = System.currentTimeMillis();
        for (int i = 0; i < 1000000; i++) {
            fastMethod.invoke(myBean, new Object[]{"haha"+i, 12});
        }
        System.out.println("fastmethod:" + (System.currentTimeMillis() - start));
        start = System.currentTimeMillis();
        Method m = SampleBean.class.getMethod("echo", String.class, int.class);
        for (int i = 0; i < 1000000; i++) {
            m.invoke(myBean, "haha"+i, 12);
        }
        System.out.println("reflect:" + (System.currentTimeMillis() - start));
        start = System.currentTimeMillis();
        for (int i = 0; i < 1000000; i++) {
            myBean.echo("haha"+i, 12);
        }
        System.out.println("normal:" + (System.currentTimeMillis() - start));

这段代码输出： fastmethod:5533 reflect:4779 normal:4691 结果是 cglib 不如 java 自己的反射 api 快?!!! 直接调和反射差的也不多，是我的这段测试有问题吗？请教一下关于反射优化的问题，谢谢。