Java各种反射性能对比

Posted 2021-02-02 生活咖啡

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对各种方法实现get方法的性能进行了一个测试。

总共有5个测试，，每个测试都是执行1亿次

1. 直接通过Java的get方法

2.通过高性能的ReflectAsm库进行测试

3.通过Java Class类自带的反射获得Method测试

4.使用Java自带的Property类获取Method测试

5.BeanUtils的getProperty测试

1 测试用Bean类

测试定义了如下一个bean类。

public class SimpleBean {
    private String name;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}

注意定义要严格遵守JavaBean规范，否则在使用和反射相关工具时会出现NoSuchMethodException异常，或者导致性能非常差，JavaBean规范中最重要的几点如下：

1.类必须是public, 拥有public无参构造器,这样能够通过反射newInstance()动态构建对象.
         String className = ...;
         Class beanClass = Class.forName(className);
         Object beanInstance = beanClass.newInstance();
2.因为反射newInstance使用的是无参构造器, 所以对象实例化和配置是分开的
3.每一个property都有一个public的getter和setter方法, 命名方式是get/set+首字母大写的property名

经测试在SimpleBean为public时，1亿次调用method.invoke方法：

javaReflectGet 100000000 times using 218 ms

而SimpleBean为默认包可见时，1一亿次调用method.invoke方法：

javaReflectGet 100000000 times using 12955 ms

2.测试代码

public class TestIterator {
    private long times = 100_000_000L;
    private SimpleBean bean;
    private String formatter = "%s %d times using %d ms";
    @Before
    public void setUp() throws Exception {
        bean = new SimpleBean();
        bean.setName("haoyifen");
    }
    //直接通过Java的get方法
    @Test
    public void directGet() {
        Stopwatch watch = Stopwatch.createStarted();
        for (long i = 0; i < times; i++) {
            bean.getName();
        }
        watch.stop();
        String result = String.format(formatter, "directGet", times, watch.elapsed(TimeUnit.MILLISECONDS));
        System.out.println(result);
    }
    //通过高性能的ReflectAsm库进行测试，仅进行一次methodAccess获取
    @Test
    public void reflectAsmGet() {
        MethodAccess methodAccess = MethodAccess.get(SimpleBean.class);
        Stopwatch watch = Stopwatch.createStarted();
        for (long i = 0; i < times; i++) {
            methodAccess.invoke(bean, "getName");
        }
        watch.stop();
        String result = String.format(formatter, "reflectAsmGet", times, watch.elapsed(TimeUnit.MILLISECONDS));
        System.out.println(result);
    }
    //通过Java Class类自带的反射获得Method测试，仅进行一次method获取
    @Test
    public void javaReflectGet() throws IllegalAccessException, NoSuchMethodException, InvocationTargetException {
        Method getName = SimpleBean.class.getMethod("getName");
        Stopwatch watch = Stopwatch.createStarted();
        for (long i = 0; i < times; i++) {
            getName.invoke(bean);
        }
        watch.stop();
        String result = String.format(formatter, "javaReflectGet", times, watch.elapsed(TimeUnit.MILLISECONDS));
        System.out.println(result);
    }
    //使用Java自带的Property属性获取Method测试，仅进行一次method获取
    @Test
    public void propertyGet() throws IllegalAccessException, NoSuchMethodException, InvocationTargetException, IntrospectionException {
        Method method = null;
        BeanInfo beanInfo = Introspector.getBeanInfo(SimpleBean.class);
        PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
        for (PropertyDescriptor propertyDescriptor : propertyDescriptors) {
            if (propertyDescriptor.getName().equals("name")) {
                method = propertyDescriptor.getReadMethod();
                break;
            }
        }
        Stopwatch watch = Stopwatch.createStarted();
        for (long i = 0; i < times; i++) {
           
            method.invoke(bean);
        }
        watch.stop();
        String result = String.format(formatter, "propertyGet", times, watch.elapsed(TimeUnit.MILLISECONDS));
        System.out.println(result);
    }
    //BeanUtils的getProperty测试
    @Test
    public void beanUtilsGet() throws IllegalAccessException, NoSuchMethodException, InvocationTargetException {
        Stopwatch watch = Stopwatch.createStarted();
        for (long i = 0; i < times; i++) {
            BeanUtils.getProperty(bean, "name");
        }
        watch.stop();
        String result = String.format(formatter, "beanUtilsGet", times, watch.elapsed(TimeUnit.MILLISECONDS));
        System.out.println(result);
    }
}