cglib proxy 源码学习_综合

背景

前段时间在写hank hsf 的工具（http://www.atatech.org/articles/23763）时，发现cndcp 中，一个单例的bean，被jmonitor 做了代理，动态生成了3个class, 其中 CndcpConsolidationTmsOrderServiceImpl

E n h a n c e r B y C G L I B

35f433a5

F a s t C l a s s B y C G L I B

1e3b1902 类的实例对象达到了7个，为了弄清楚这个原因，所以就跟踪了下cglib中proxy 部分的源代码。

jmonitor 配置文件。

   <bean id="jmonitor-interceptor" class="com.alibaba.alimonitor.jmonitor.plugin.spring.JMonitorMethodInterceptor" /><!-- 配置你想要拦截的namespace --><bean id="jmonitor-pointcut" class="org.springframework.aop.support.JdkRegexpMethodPointcut" scope="prototype"><property name="patterns"><list><value>com.alibaba.cainiao.cndcp.hsfservice.event.*</value><value>com.alibaba.cainiao.cndcp.hsfservice.order.*</value><value>com.alibaba.cainiao.cndcp.hsfservice.schedule.*</value></list></property></bean><aop:config proxy-target-class="true"><aop:advisor advice-ref="jmonitor-interceptor" pointcut-ref="jmonitor-pointcut" /></aop:config>

cglib proxy 示例

cglib 源码地址： https://github.com/cglib/cglib.git，在包net.sf.cglib.samples 中有一个proxy 的示例，但是代码存在一些问题。

这里先从一个简单的示例入手，包含3个类:
1、MyBean 一个普通的javabean ,有两个方法。
2、MyMethodInterceptor 一个拦截器，在方法执行前，向控制台输出一些信息。
3、ProxyMain


public class MyBean implements java.io.Serializable {String sampleProperty = "original";public MyBean(){}public MyBean(String sampleProperty){super();this.sampleProperty = sampleProperty;}public void setSampleProperty(String value) {System.out.println(this + "========in bean setSampleProperty:::: " + sampleProperty);this.sampleProperty = value;}public int doPlug(int num) {return num + 1;}}


public class MyMethodInterceptor implements MethodInterceptor {private String interceptorNo;public MyMethodInterceptor(String interceptorNo){super();this.interceptorNo = interceptorNo;}public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable {Object retValFromSuper = null;System.out.println("#######interceptor:" + interceptorNo + "####execut method:" + method.getName());retValFromSuper = proxy.invokeSuper(obj, args);return retValFromSuper;}
}

public class ProxyMain {public static void main(String args[]) {System.setProperty(DebuggingClassWriter.DEBUG_LOCATION_PROPERTY, "/tmp/2");// 第一步，创建一个Enhancer对象Enhancer e = new Enhancer();// 第二步，设置需要拦截的classe.setSuperclass(MyBean.class);// 第三部，添加两个拦截器，MethodInterceptor[] interceptors = new MethodInterceptor[2];interceptors[0] = new MyMethodInterceptor("0");//第一个拦截器interceptors[1] = new MyMethodInterceptor("1");//第二个拦截器e.setCallbacks(interceptors);//第四步，设置拦截器的过滤规则e.setCallbackFilter(new CallbackFilter() {public int accept(Method method) {if (method.getDeclaringClass().getName().equals("java.lang.Object")) {// 当执行的是 从父类 object 上继承下来的方法如 equals， toString 等将调用拦截器材数组中的第二个拦截器。return 1;}return 0;//默认调用第一个拦截器}});//cglib 生成代理类MyBean mybean = (MyBean) e.create();mybean.toString();mybean.setSampleProperty("TEST222222");mybean.setSampleProperty("TEST333333");}}

这里需要注意的是，拦截器虽然可以定义多个，但是经过filter 后生效的只能有一个。当然你可以不定义filter，但那样当你传入多个拦截器时，就会 enhance.create 的时候就会抛出异常。*【但是spring 中定义可以定义多个拦截器，那是由于spring 在拦截器上又做了一层封装，下一篇文章会介绍到】*

这里看到动态生成的3个类：
MyBean

E n h a n c e r B y C G L I B

7522cdf0
MyBean

F a s t C l a s s B y C G L I B

15105a78
MyBean

E n h a n c e r B y C G L I B

7522cdf0

F a s t C l a s s B y C G L I B

69ea8397

其中 MyBean

E n h a n c e r B y C G L I B

7522cdf0 为 MyBean的代理类。

代码执行后，jmap 查看内存对象，【这里同spring aop相比缺少原始类的一个对象，这会在spring aop 文章中介绍到】

cglib proxy 核心代码分析

【引用：http://agapple.iteye.com/blog/799827 】

asm

cglib 是通过调用asm 生成字节码的：
asm 生成字节码的流程很简单：定义一个 ClassWriter ，它有一系列的visit* 方法:
ClassWriter.visit 定义class实现的接口，版本，类名等。
ClassWriter.visitMethod 定义class中的方法
ClassWriter.visitField定义class中的属性
最后 ClassWriter.toByteArray 负责生成字节码。
asm 加载class ：通过调用ClassLoader.defineClass(String name, byte[] b, int off, int len)
// byte[] b 为刚才ClassWriter生成的字节码。
asm 中 ClassRead 用于从byte[]，中获取class 上相关信息。

cglib 中代理类的生成

Cglib中是通过ClassGenerator的子类实现不同场景的字节码的生成的。[ FastClass(G
enerate ) 表示 Generate 是 FastClass的内部内。]

其中： spring aop 涉及到两个核心的class Generate: Enhance 和 FastClass(Generate)

类生成器： Enhance 用于生成我们的代理类。
类生成器： FastClass(Generate) ，为代理的每个方法生成一个快速的定位类，用于取代反射。

代理类MyBean

E n h a n c e r B y C G L I B

7522cdf0 反编译后代码如下：

package net.sf.cglib.samples;import java.lang.reflect.Method;
import net.sf.cglib.core.ReflectUtils;
import net.sf.cglib.core.Signature;
import net.sf.cglib.proxy.Callback;
import net.sf.cglib.proxy.Factory;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;public class MyBean$$EnhancerByCGLIB$$69c57fb0extends MyBeanimplements Factory
{private boolean CGLIB$BOUND;private static final ThreadLocal CGLIB$THREAD_CALLBACKS;private static final Callback[] CGLIB$STATIC_CALLBACKS;private MethodInterceptor CGLIB$CALLBACK_0;private MethodInterceptor CGLIB$CALLBACK_1;private static final Method CGLIB$setSampleProperty$0$Method;private static final MethodProxy CGLIB$setSampleProperty$0$Proxy;private static final Object[] CGLIB$emptyArgs;private static final Method CGLIB$doPlug$1$Method;private static final MethodProxy CGLIB$doPlug$1$Proxy;private static final Method CGLIB$finalize$2$Method;private static final MethodProxy CGLIB$finalize$2$Proxy;private static final Method CGLIB$equals$3$Method;private static final MethodProxy CGLIB$equals$3$Proxy;private static final Method CGLIB$toString$4$Method;private static final MethodProxy CGLIB$toString$4$Proxy;private static final Method CGLIB$hashCode$5$Method;private static final MethodProxy CGLIB$hashCode$5$Proxy;private static final Method CGLIB$clone$6$Method;private static final MethodProxy CGLIB$clone$6$Proxy;static void CGLIB$STATICHOOK1(){CGLIB$THREAD_CALLBACKS = new ThreadLocal();CGLIB$emptyArgs = new Object[0];Class localClass1 = Class.forName("net.sf.cglib.samples.MyBean$$EnhancerByCGLIB$$69c57fb0");Class localClass2;Method[] tmp95_92 = ReflectUtils.findMethods(new String[] { "finalize", "()V", "equals", "(Ljava/lang/Object;)Z", "toString", "()Ljava/lang/String;", "hashCode", "()I", "clone", "()Ljava/lang/Object;" }, (localClass2 = Class.forName("java.lang.Object")).getDeclaredMethods());CGLIB$finalize$2$Method = tmp95_92[0];CGLIB$finalize$2$Proxy = MethodProxy.create(localClass2, localClass1, "()V", "finalize", "CGLIB$finalize$2");Method[] tmp115_95 = tmp95_92;CGLIB$equals$3$Method = tmp115_95[1];CGLIB$equals$3$Proxy = MethodProxy.create(localClass2, localClass1, "(Ljava/lang/Object;)Z", "equals", "CGLIB$equals$3");Method[] tmp135_115 = tmp115_95;CGLIB$toString$4$Method = tmp135_115[2];CGLIB$toString$4$Proxy = MethodProxy.create(localClass2, localClass1, "()Ljava/lang/String;", "toString", "CGLIB$toString$4");Method[] tmp155_135 = tmp135_115;CGLIB$hashCode$5$Method = tmp155_135[3];CGLIB$hashCode$5$Proxy = MethodProxy.create(localClass2, localClass1, "()I", "hashCode", "CGLIB$hashCode$5");Method[] tmp175_155 = tmp155_135;CGLIB$clone$6$Method = tmp175_155[4];CGLIB$clone$6$Proxy = MethodProxy.create(localClass2, localClass1, "()Ljava/lang/Object;", "clone", "CGLIB$clone$6");tmp175_155;Method[] tmp233_230 = ReflectUtils.findMethods(new String[] { "setSampleProperty", "(Ljava/lang/String;)V", "doPlug", "(I)I" }, (localClass2 = Class.forName("net.sf.cglib.samples.MyBean")).getDeclaredMethods());CGLIB$setSampleProperty$0$Method = tmp233_230[0];CGLIB$setSampleProperty$0$Proxy = MethodProxy.create(localClass2, localClass1, "(Ljava/lang/String;)V", "setSampleProperty", "CGLIB$setSampleProperty$0");Method[] tmp253_233 = tmp233_230;CGLIB$doPlug$1$Method = tmp253_233[1];CGLIB$doPlug$1$Proxy = MethodProxy.create(localClass2, localClass1, "(I)I", "doPlug", "CGLIB$doPlug$1");tmp253_233;return;}final void CGLIB$setSampleProperty$0(String paramString){super.setSampleProperty(paramString);}public final void setSampleProperty(String paramString){MethodInterceptor tmp4_1 = this.CGLIB$CALLBACK_0;if (tmp4_1 == null){tmp4_1;CGLIB$BIND_CALLBACKS(this);}if (this.CGLIB$CALLBACK_0 != null) {return;}super.setSampleProperty(paramString);}final int CGLIB$doPlug$1(int paramInt){return super.doPlug(paramInt);}public final int doPlug(int paramInt){MethodInterceptor tmp4_1 = this.CGLIB$CALLBACK_0;if (tmp4_1 == null){tmp4_1;CGLIB$BIND_CALLBACKS(this);}MethodInterceptor tmp17_14 = this.CGLIB$CALLBACK_0;if (tmp17_14 != null){Object tmp49_44 = tmp17_14.intercept(this, CGLIB$doPlug$1$Method, new Object[] { new Integer(paramInt) }, CGLIB$doPlug$1$Proxy);tmp49_44;return tmp49_44 == null ? 0 : ((Number)tmp49_44).intValue();}return super.doPlug(paramInt);}final void CGLIB$finalize$2()throws Throwable{super.finalize();}protected final void finalize()throws Throwable{MethodInterceptor tmp4_1 = this.CGLIB$CALLBACK_1;if (tmp4_1 == null){tmp4_1;CGLIB$BIND_CALLBACKS(this);}if (this.CGLIB$CALLBACK_1 != null) {return;}super.finalize();}final boolean CGLIB$equals$3(Object paramObject){return super.equals(paramObject);}public final boolean equals(Object paramObject){MethodInterceptor tmp4_1 = this.CGLIB$CALLBACK_1;if (tmp4_1 == null){tmp4_1;CGLIB$BIND_CALLBACKS(this);}MethodInterceptor tmp17_14 = this.CGLIB$CALLBACK_1;if (tmp17_14 != null){Object tmp41_36 = tmp17_14.intercept(this, CGLIB$equals$3$Method, new Object[] { paramObject }, CGLIB$equals$3$Proxy);tmp41_36;return tmp41_36 == null ? false : ((Boolean)tmp41_36).booleanValue();}return super.equals(paramObject);}final String CGLIB$toString$4(){return super.toString();}public final String toString(){MethodInterceptor tmp4_1 = this.CGLIB$CALLBACK_1;if (tmp4_1 == null){tmp4_1;CGLIB$BIND_CALLBACKS(this);}MethodInterceptor tmp17_14 = this.CGLIB$CALLBACK_1;if (tmp17_14 != null) {return (String)tmp17_14.intercept(this, CGLIB$toString$4$Method, CGLIB$emptyArgs, CGLIB$toString$4$Proxy);}return super.toString();}final int CGLIB$hashCode$5(){return super.hashCode();}public final int hashCode(){MethodInterceptor tmp4_1 = this.CGLIB$CALLBACK_1;if (tmp4_1 == null){tmp4_1;CGLIB$BIND_CALLBACKS(this);}MethodInterceptor tmp17_14 = this.CGLIB$CALLBACK_1;if (tmp17_14 != null){Object tmp36_31 = tmp17_14.intercept(this, CGLIB$hashCode$5$Method, CGLIB$emptyArgs, CGLIB$hashCode$5$Proxy);tmp36_31;return tmp36_31 == null ? 0 : ((Number)tmp36_31).intValue();}return super.hashCode();}final Object CGLIB$clone$6()throws CloneNotSupportedException{return super.clone();}protected final Object clone()throws CloneNotSupportedException{MethodInterceptor tmp4_1 = this.CGLIB$CALLBACK_1;if (tmp4_1 == null){tmp4_1;CGLIB$BIND_CALLBACKS(this);}MethodInterceptor tmp17_14 = this.CGLIB$CALLBACK_1;if (tmp17_14 != null) {return tmp17_14.intercept(this, CGLIB$clone$6$Method, CGLIB$emptyArgs, CGLIB$clone$6$Proxy);}return super.clone();}public static MethodProxy CGLIB$findMethodProxy(Signature paramSignature){String tmp4_1 = paramSignature.toString();switch (tmp4_1.hashCode()){case -1574182249: if (tmp4_1.equals("finalize()V")) {return CGLIB$finalize$2$Proxy;}break;}}public MyBean$$EnhancerByCGLIB$$69c57fb0(){CGLIB$BIND_CALLBACKS(this);}public MyBean$$EnhancerByCGLIB$$69c57fb0(String paramString){super(paramString);CGLIB$BIND_CALLBACKS(this);}public static void CGLIB$SET_THREAD_CALLBACKS(Callback[] paramArrayOfCallback){CGLIB$THREAD_CALLBACKS.set(paramArrayOfCallback);}public static void CGLIB$SET_STATIC_CALLBACKS(Callback[] paramArrayOfCallback){CGLIB$STATIC_CALLBACKS = paramArrayOfCallback;}private static final void CGLIB$BIND_CALLBACKS(Object paramObject){69c57fb0 local69c57fb0 = (69c57fb0)paramObject;if (!local69c57fb0.CGLIB$BOUND){local69c57fb0.CGLIB$BOUND = true;Object tmp23_20 = CGLIB$THREAD_CALLBACKS.get();if (tmp23_20 == null){tmp23_20;CGLIB$STATIC_CALLBACKS;}Callback[] tmp44_39 = ((Callback[])tmp23_20);69c57fb0 tmp44_42 = local69c57fb0;tmp44_42.CGLIB$CALLBACK_1 = ((MethodInterceptor)tmp44_39[1]);tmp44_42.CGLIB$CALLBACK_0 = (tmp31_28 == null ? tmp31_28 : (MethodInterceptor)tmp44_39[0]);}}public Object newInstance(Callback[] paramArrayOfCallback){CGLIB$SET_THREAD_CALLBACKS(paramArrayOfCallback);CGLIB$SET_THREAD_CALLBACKS(null);return new 69c57fb0();}public Object newInstance(Callback paramCallback){throw new IllegalStateException("More than one callback object required");CGLIB$SET_THREAD_CALLBACKS(null);return new 69c57fb0();}public Object newInstance(Class[] paramArrayOfClass, Object[] paramArrayOfObject, Callback[] paramArrayOfCallback){CGLIB$SET_THREAD_CALLBACKS(paramArrayOfCallback);Class[] tmp9_8 = paramArrayOfClass;switch (tmp9_8.length){case 0: tmp9_8;break;case 1: void tmp39_33 = new 69c57fb0();if (tmp39_33[0].getName().equals("java.lang.String")) {tmp39_33;}break;}}public Callback getCallback(int paramInt){CGLIB$BIND_CALLBACKS(this);switch (paramInt){case 0: break;case 1: break;}return null;}public void setCallback(int paramInt, Callback paramCallback){switch (paramInt){case 0: this.CGLIB$CALLBACK_0 = ((MethodInterceptor)paramCallback);break;case 1: this.CGLIB$CALLBACK_1 = ((MethodInterceptor)paramCallback);break;}}public Callback[] getCallbacks(){CGLIB$BIND_CALLBACKS(this);return new Callback[] { this.CGLIB$CALLBACK_0, this.CGLIB$CALLBACK_1 };}public void setCallbacks(Callback[] paramArrayOfCallback){Callback[] tmp2_1 = paramArrayOfCallback;this.CGLIB$CALLBACK_0 = ((MethodInterceptor)tmp2_1[0]);this.CGLIB$CALLBACK_1 = ((MethodInterceptor)tmp2_1[1]);}static {}
}

代理类方法的执行流程

以方法，MyBean.doPlus 为例，MyBean

E n h a n c e r B y C G L I B

7522cdf0为其生成了两个方法和一个MethodProxy 对象。

a、 final int CGLIB$doPlug$1 //直接调用其父类的方法。
b、 public final int doPlug(int paramInt) 判断是否有拦截器，有拦截器执行拦截器的intercept 方法。
c、 MethodProxy 对象 . MethodProxy 的两个方法 invokeSuper （对应CGLIB$doPlug$1方法）和invoke（对应doPlug方法），如果当前传递的对象是Enhance后的（直接使用cglib 传递的都是enhance 后的对象），这时就需要调用invokeSuper，否则就会出现循环调用，导致对象溢出。

流程：调用doplug的步骤

1 MyBean $E n h a n c e r B y C G L I B$ 7522cdf0.doPlus
2 MyMethodInterceptor.intercept
3 MethodProxy.invokeSuper
4 MethodProxy 用有个 FastClassInfo 属性，在 MethodProxy.invokeSuper 或 MethodProxy.invoke 第一次被执行时，会创建该对象。
```
private static class FastClassInfo {FastClass f1;FastClass f2;int i1;int i2;
}
```
FastClassInfo.f1 对应的就是： MyBean

FastClassByCGLIB
15105a78，而 FastClassInfo.f2 对应的就是：MyBean
EnhancerByCGLIB
7522cdf0
FastClassByCGLIB
69ea8397，他们的作用取代反射，直接使用使用坐标查询，f1用于定位原始bean的doplus 方法， f2 用于定位 enhance 的bean （CGLIB$doPlug$1）方法。 cglib 这里是为了FastClass的简介，对代理类的每个Method 生成一个FastClass。这也就是为什么我们在cndcp 中看到 CndcpConsolidationTmsOrderServiceImpl
EnhancerByCGLIB
35f433a5
FastClassByCGLIB
1e3b1902 有7个对象
那为什么 CndcpConsolidationTmsOrderServiceImpl
FastClassByCGLIB
6aa1ec88 对象只有3个，而不是7个。
那是因为 CndcpConsolidationTmsOrderServiceImpl本身只定义了3个public 方法, 而其父类Object 还有4个非final 的protected 或public 方法（toString，finalize,hashCode,equal）, 因此还会为原始bean生成4个 Object
FastClassByCGLIB
xxx 对象。

相关文档
cglib 已经停止几年没有维护了，相关文档比较少。
http://agapple.iteye.com/blog/799827 这也是我厂同学写的。
源码地址： https://github.com/cglib/cglib.git