Java各類反射性能對比

時間 2019-11-09

標籤 java 各類反射性能對比欄目 Java 简体版

原文原文鏈接

對各類方法實現get方法的性能進行了一個測試。java

總共有5個測試，，每一個測試都是執行1億次工具

1. 直接經過Java的get方法性能

2.經過高性能的ReflectAsm庫進行測試測試

3.經過Java Class類自帶的反射得到Method測試this

4.使用Java自帶的Property類獲取Method測試spa

5.BeanUtils的getProperty測試pwa

1 測試用Bean類

測試定義了以下一個bean類。code

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

注意定義要嚴格遵照JavaBean規範，不然在使用和反射相關工具時會出現NoSuchMethodException異常，或者致使性能很是差，JavaBean規範中最重要的幾點以下：orm

1.類必須是public, 擁有public無參構造器,這樣可以經過反射newInstance()動態構建對象.
         String className = ...;
         Class beanClass = Class.forName(className);
         Object beanInstance = beanClass.newInstance();
2.由於反射newInstance使用的是無參構造器, 因此對象實例化和配置是分開的
3.每個property都有一個public的getter和setter方法, 命名方式是get/set+首字母大寫的property名

經測試在SimpleBean爲public時，1億次調用method.invoke方法：對象

javaReflectGet 100000000 times using 218 ms

而SimpleBean爲默認包可見時，1一億次調用method.invoke方法：

javaReflectGet 100000000 times using 12955 ms

2.測試代碼

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");
    }
    //直接經過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);
    }
    //經過高性能的ReflectAsm庫進行測試，僅進行一次methodAccess獲取
    @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);
    }
    //經過Java Class類自帶的反射得到Method測試，僅進行一次method獲取
    @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自帶的Property屬性獲取Method測試，僅進行一次method獲取
    @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測試
    @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);
    }
}