Spring中JDK动态代理和CGLIB动态代理的性能比较
新项目开始之前领导让研究下公司原有的框架(基于struts1.2.9+spring2.0.6)，比较古老了。读service基类时发现竟然将request穿透到了service层(request为BaseService的实例变量)，这样service就变成了有状态Bean，使service层变成了非线程安全，导致用Spring容器管理service的时候不得不使用prototype的scope
我们知道，service由于要做事务的包装，需要创建代理对象，spring中使用JDK动态代理或者CGLIB动态代理来创建代理对象，据说JDK动态代理创建对象的时间快于CGLIB，但是性能比CGLIB差（接下来我会测试这个观点），所以我得出以下结论：
1.spring在bean的scope为prototype的情况下，因为是延迟实例化bean，所以最好使用JDK的API创建代理对象；
2.反之对于singleton对象，spring默认是容器启动时就初始化bean，最好使用CGLIB来创建对象
把service配置成singleton我觉得性能方面显然要更好些，如果非要将request穿透到service层，是不是可以考虑用ThreadLocal？
在测试之前，我们先确定spring是以什么方式使用JDK动态代理和CGLIB的，如图：
JDK动态代理：
CGLIB动态代理：
接下来对测试下JDK动态代理和CGLIB动态代理的性能（CGLIB测试代码也和spring一样使用MethodInterceptor）
先贴上测试代码
public interface CountService { int count();}public class CountServiceImpl implements CountService { private int count = 0; public int count() { return ++count; }}import java.io.File;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Proxy;import java.text.DecimalFormat;import net.sf.cglib.core.DefaultGeneratorStrategy;import net.sf.cglib.proxy.Enhancer;import net.sf.cglib.proxy.MethodInterceptor;import net.sf.cglib.proxy.MethodProxy;@SuppressWarnings("unused")public class DynamicProxyPerformanceTest { public static void main(String[] args) throws Exception { CountService delegate = new CountServiceImpl(); long time = System.currentTimeMillis(); CountService jdkProxy = createJdkDynamicProxy(delegate); time = System.currentTimeMillis() - time; System.out.println("Create JDK Proxy: " + time + " ms"); time = System.currentTimeMillis(); CountService cglibProxy = createCglibDynamicProxy(delegate); time = System.currentTimeMillis() - time; System.out.println("Create CGLIB Proxy: " + time + " ms"); for (int i = 0; i < 3; i++) { test(jdkProxy, "Run JDK Proxy: "); test(cglibProxy, "Run CGLIB Proxy: "); System.out.println("-------------------"); } } private static void test(CountService service, String label) throws Exception { service.count(); // warm up int count = 10000000; long time = System.currentTimeMillis(); for (int i = 0; i < count; i++) { service.count(); } time = System.currentTimeMillis() - time; System.out.println(label + time + " ms, " + new DecimalFormat().format(count * 1000 / time) + " t/s"); } private static CountService createJdkDynamicProxy(final CountService delegate) { CountService jdkProxy = (CountService) Proxy.newProxyInstance(ClassLoader.getSystemClassLoader(), new Class[] { CountService.class }, new JdkHandler(delegate)); // 反汇编字节码用，测试的时候注释掉这段代码，不然影响测试结果 // 下面一行代码参照java.lang.reflect.Proxy// byte[] proxyClassFile =// sun.misc.ProxyGenerator.generateProxyClass(// jdkProxy.getClass().getName(), jdkProxy.getClass().getInterfaces());// try {// FileOutputStream fos =// new FileOutputStream(new File(jdkProxy.getClass().getName() + ".class"));// fos.write(proxyClassFile, 0, proxyClassFile.length);// } catch (FileNotFoundException e) {// e.printStackTrace();// } catch (IOException e) {// e.printStackTrace();// } return jdkProxy; } private static class JdkHandler implements InvocationHandler { final Object delegate; JdkHandler(Object delegate) { this.delegate = delegate; } public Object invoke(Object object, Method method, Object[] objects) throws Throwable { return method.invoke(delegate, objects); } } private static CountService createCglibDynamicProxy(final CountService delegate) throws Exception { Enhancer enhancer = new Enhancer(); enhancer.setSuperclass(CountServiceImpl.class); enhancer.setCallback(new MethodInterceptor() { @Override public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable { return proxy.invokeSuper(obj, args); } }); CountServiceImpl cglibProxy = (CountServiceImpl) enhancer.create(); // 反汇编字节码用，测试的时候注释掉这段代码，不然影响测试结果 // 下面一行代码参照net.sf.cglib.core.AbstractClassGenerator类中byte[] b = strategy.generate(this);// byte[] proxyClassFile = new DefaultGeneratorStrategy().generate(enhancer);// try {// FileOutputStream fos =// new FileOutputStream(new File(cglibProxy.getClass().getName() + ".class"));// fos.write(proxyClassFile, 0, proxyClassFile.length);// } catch (FileNotFoundException e) {// e.printStackTrace();// } catch (IOException e) {// e.printStackTrace();// } return cglibProxy; }}Create JDK Proxy: 13 msCreate CGLIB Proxy: 201 msRun JDK Proxy: 1571 ms, 897,559 t/sRun CGLIB Proxy: 824 ms, 1,711,244 t/s-------------------Run JDK Proxy: 1519 ms, 928,285 t/sRun CGLIB Proxy: 576 ms, 2,448,030 t/s-------------------Run JDK Proxy: 1546 ms, 912,073 t/sRun CGLIB Proxy: 590 ms, 2,389,941 t/s-------------------
Create JDK Proxy: 14 msCreate CGLIB Proxy: 204 msRun JDK Proxy: 1608 ms, 876,906 t/sRun CGLIB Proxy: 529 ms, 2,665,530 t/s-------------------Run JDK Proxy: 1591 ms, 886,276 t/sRun CGLIB Proxy: 405 ms, 3,481,642 t/s-------------------Run JDK Proxy: 1624 ms, 868,266 t/sRun CGLIB Proxy: 405 ms, 3,481,642 t/s-------------------
Create JDK Proxy: 8 msCreate CGLIB Proxy: 99 msRun JDK Proxy: 911 ms, 1,547,821 t/sRun CGLIB Proxy: 435 ms, 3,241,529 t/s-------------------Run JDK Proxy: 870 ms, 1,620,764 t/sRun CGLIB Proxy: 399 ms, 3,533,998 t/s-------------------Run JDK Proxy: 894 ms, 1,577,254 t/sRun CGLIB Proxy: 404 ms, 3,490,260 t/s-------------------
Create JDK Proxy: 43 msCreate CGLIB Proxy: 129 msRun JDK Proxy: 940 ms, 1,500,069 t/sRun CGLIB Proxy: 299 ms, 4,715,937 t/s-------------------Run JDK Proxy: 921 ms, 1,531,015 t/sRun CGLIB Proxy: 269 ms, 5,241,878 t/s-------------------Run JDK Proxy: 932 ms, 1,512,945 t/sRun CGLIB Proxy: 265 ms, 5,321,001 t/s-------------------
public final int count() throws ; Code: 0: aload_0 1: getfield #16 // Field java/lang/reflect/Proxy.h:Ljava/lang/reflect/InvocationHandler; 4: aload_0 5: getstatic #50 // Field m3:Ljava/lang/reflect/Method; 8: aconst_null 9: invokeinterface #28, 4 // InterfaceMethod java/lang/reflect/InvocationHandler.invoke:(Ljava/lang/Object;Ljava/lang/reflect/Method;[Ljava/lang/Object;)Ljava/lang/Object; 14: checkcast #52 // class java/lang/Integer 17: invokevirtual #55 // Method java/lang/Integer.intValue:()I 20: ireturn 21: athrow 22: astore_1 23: new #42 // class java/lang/reflect/UndeclaredThrowableException 26: dup 27: aload_1 28: invokespecial #45 // Method java/lang/reflect/UndeclaredThrowableException."<init>":(Ljava/lang/Throwable;)V 31: athrow Exception table: from to target type 0 21 21 Class java/lang/Error 0 21 21 Class java/lang/RuntimeException 0 21 22 Class java/lang/Throwable
public final int count(); Code: 0: aload_0 1: getfield #37 // Field CGLIB$CALLBACK_0:Lnet/sf/cglib/proxy/MethodInterceptor; 4: dup 5: ifnonnull 17 8: pop 9: aload_0 10: invokestatic #41 // Method CGLIB$BIND_CALLBACKS:(Ljava/lang/Object;)V 13: aload_0 14: getfield #37 // Field CGLIB$CALLBACK_0:Lnet/sf/cglib/proxy/MethodInterceptor; 17: dup 18: ifnull 52 21: aload_0 22: getstatic #43 // Field CGLIB$count$0$Method:Ljava/lang/reflect/Method; 25: getstatic #45 // Field CGLIB$emptyArgs:[Ljava/lang/Object; 28: getstatic #47 // Field CGLIB$count$0$Proxy:Lnet/sf/cglib/proxy/MethodProxy; 31: invokeinterface #53, 5 // InterfaceMethod net/sf/cglib/proxy/MethodInterceptor.intercept:(Ljava/lang/Object;Ljava/lang/reflect/Method;[Ljava/lang/Object;Lnet/sf/cglib/proxy/MethodProxy;)Ljava/lang/Object; 36: dup 37: ifnonnull 45 40: pop 41: iconst_0 42: goto 51 45: checkcast #55 // class java/lang/Number 48: invokevirtual #58 // Method java/lang/Number.intValue:()I 51: ireturn 52: aload_0 53: invokespecial #35 // Method CountServiceImpl.count:()I 56: ireturn