Java查看動態代理生成的代碼
1.創建一個導出生成類的agent
agent是一個用來個jvm打交道的東西，需要實現一個靜態的public static void premain(String agentArgs, Instrumentation inst) 方法.我使用如下的代碼創建agent
package ctgu.jagent;
import java.io.File;
import java.io.FileOutputStream;
import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.lang.instrument.Instrumentation;
import java.security.ProtectionDomain;
public class CustomAgent implements ClassFileTransformer {
public static void premain(String agentArgs, Instrumentation inst) {
inst.addTransformer(new CustomAgent());
}
@Override
public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined,
ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
if (!className.startsWith("java") && !className.startsWith("sun")) {
// 既不是java也不是sun開頭的
// 導出代碼
int lastIndexOf = className.lastIndexOf("/") + 1;
String fileName = className.substring(lastIndexOf) + ".class";
exportClazzToFile("E:/javaeeworkspace/bytecode/exported/", fileName, classfileBuffer);
System.out.println(className + " --> EXPORTED Succeess!");
}
return classfileBuffer;
}
/**
*
* @param dirPath
*目錄以/結尾，且必須存在
* @param fileName
* @param data
*/
private void exportClazzToFile(String dirPath, String fileName, byte[] data) {
try {
File file = new File(dirPath + fileName);
if (!file.exists()) {
file.createNewFile();
}
FileOutputStream fos = new FileOutputStream(file);
fos.write(data);
fos.close();
} catch (Exception e) {
System.out.println("exception occured while doing some file operation");
e.printStackTrace();
}
}
}
然后使用eclipse的導出功能導出jar（注意agent必須是jar的形式存在），在向導中使用指定的MANIFEST.MF文件，MANIFEST.MF文件的內容如下
Manifest-Version: 1.0
Premain-Class: ctgu.jagent.CustomAgent
注意，這個premain-Class就是帶有premain靜態方法的類。
如果你使用maven，也可以用如下plugin
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifestFile>src/main/resources/META-INF/MANIFEST.MF</manifestFile>
</archive>
</configuration>
</plugin>
把manifestFile換成你存放自定義MANIFEST.MF的路徑，然后mvn package就可以了。
導出的jar包這里假設叫jagent.jar
2. 使用jagent.jar
把jagent.jar放到工程下，運行的時候加上jvm參數
-javaagent:jagent.jar
注意:左右都沒有空格，要是jvm提示找不到的話，可以用eclispe把jagent.jar加入到buildpath中。
3. 使用動態代理
3.0 原始目標的接口與實現
接口定義如下：
package ctgu.bytecode.proxy.service;
public interface HelloService {
public String sayHello(String name) ;
}
實現如下：
package ctgu.bytecode.proxy.service.impl;
import ctgu.bytecode.proxy.service.HelloService;
public class HelloServiceImpl implements HelloService{
@Override
public String sayHello(String name) {
return "Hello "+name;
}
}
3.1 使用jdk的代理
private static void javaDynamicProxy() {
HelloService helloService=new HelloServiceImpl();
MyInvocationHandler handler=new MyInvocationHandler(helloService);
HelloService proxy = (HelloService)Proxy.newProxyInstance(HelloService.class.getClassLoader(),
new Class<?>[]{HelloService.class}, handler);
String sayHello = proxy.sayHello("woober");
System.out.println(sayHello);
}
其中MyInvocationHandler的代碼如下：
package ctgu.bytecode.proxy;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
public class MyInvocationHandler implements InvocationHandler {
Object trueTarget;
public MyInvocationHandler(Object target) {
this.trueTarget=target;
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
System.out.println("before invoke method:"+method.getName());
Object result = method.invoke(trueTarget, args);
System.out.println("invoke finish return:"+result);
return result;
}
}
運行后輸出：
ctgu/bytecode/TestMain --> EXPORTED Succeess!
ctgu/bytecode/proxy/service/impl/HelloServiceImpl --> EXPORTED Succeess!
ctgu/bytecode/proxy/service/HelloService --> EXPORTED Succeess!
ctgu/bytecode/proxy/MyInvocationHandler --> EXPORTED Succeess!
com/sun/proxy/$Proxy0 --> EXPORTED Succeess!
before invoke method:sayHello
invoke finish return:Hello woober
Hello woober
在第4部分會分析生成com/sun/proxy/$Proxy0的反編譯代碼。
3.2 使用cglib代理
private static void cgLibProxy(){
HelloService helloService=new HelloServiceImpl();
MyMethodIntercepter intercepter=new MyMethodIntercepter(helloService);
HelloService proxy = (HelloService)Enhancer.create(HelloService.class,intercepter);
System.err.println("Proxy class name is "+proxy.getClass().getName());
System.out.println(proxy.sayHello("Woober"));
}
其中MyMethodIntercepter代碼如下：
package ctgu.bytecode.proxy;
import java.lang.reflect.Method;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;
public class MyMethodIntercepter implements MethodInterceptor{
Object trueTarget;
public MyMethodIntercepter(Object target) {
trueTarget=target;
}
@Override
public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable {
System.out.println("In cglib before invoke");
//這個methodProxy 是目標方法的一個代理，下面可以看出來
Object result = proxy.invoke(trueTarget, args);
System.out.println("In cglib after invoke");
return result;
}
}
運行輸出：
ctgu/bytecode/TestMain --> EXPORTED Succeess!
net/sf/cglib/proxy/Callback --> EXPORTED Succeess!
ctgu/bytecode/proxy/service/impl/HelloServiceImpl --> EXPORTED Succeess!
ctgu/bytecode/proxy/service/HelloService --> EXPORTED Succeess!
ctgu/bytecode/proxy/MyMethodIntercepter --> EXPORTED Succeess!
net/sf/cglib/proxy/MethodInterceptor --> EXPORTED Succeess!
net/sf/cglib/proxy/Enhancer --> EXPORTED Succeess!
中間省略大量cglib的類還有asm的類.....
ctgu/bytecode/proxy/service/HelloService$$EnhancerByCGLIB$$1af19a1d --> EXPORTED Succeess!
net/sf/cglib/proxy/MethodProxy --> EXPORTED Succeess!
net/sf/cglib/proxy/MethodProxy$CreateInfo --> EXPORTED Succeess!
In cglib before invoke
Proxy class name is ctgu.bytecode.proxy.service.HelloService$$EnhancerByCGLIB$$1af19a1d
省略大量cglib的類...
ctgu/bytecode/proxy/service/HelloService$$FastClassByCGLIB$$c2826506 --> EXPORTED Succeess!
ctgu/bytecode/proxy/service/HelloService$$EnhancerByCGLIB$$1af19a1d$$FastClassByCGLIB$$a45a31f6 --> EXPORTED Succeess!
In cglib after invoke
Hello Woober
注意這兩句話的順序
In cglib before invoke
Proxy class name is ctgu.bytecode.proxy.service.HelloService$$EnhancerByCGLIB$$1af19a1d
按理說后面應該在后面這句應該在前面的，因為我使用system.err打的Proxy class name is這一句，跟out不是同一個流，所以以順序不對（因為err會在eclipse里面標紅，比較好看...）
下面重點關注ctgu.bytecode.proxy.service.HelloService$$EnhancerByCGLIB$$1af19a1d這個類
4. 查看生成類的源碼
找一個順手的反編譯器，我用的是Bytecode Viewer ，github地址https://github.com/Konloch/bytecode-viewer
4.1 JDK動態代理反編譯
/*
* Decompiled with CFR 0_110.
*
* Could not load the following classes:
* com.sun.proxy.$Proxy0
* ctgu.bytecode.proxy.service.HelloService
*/
package com.sun.proxy;
import ctgu.bytecode.proxy.service.HelloService;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.lang.reflect.UndeclaredThrowableException;
public final class $Proxy0
extends Proxy
implements HelloService {
private static Method m1;
private static Method m3;
private static Method m2;
private static Method m0;
public $Proxy0(InvocationHandler invocationHandler) {
super(invocationHandler);
}
public final boolean equals(Object object) {
try {
return (Boolean)this.h.invoke((Object)this, m1, new Object[]{object});
}
catch (Error | RuntimeException v0) {
throw v0;
}
catch (Throwable var2_2) {
throw new UndeclaredThrowableException(var2_2);
}
}
public final String sayHello(String string) {
try {
return (String)this.h.invoke((Object)this, m3, new Object[]{string});
}
catch (Error | RuntimeException v0) {
throw v0;
}
catch (Throwable var2_2) {
throw new UndeclaredThrowableException(var2_2);
}
}
public final String toString() {
try {
return (String)this.h.invoke((Object)this, m2, null);
}
catch (Error | RuntimeException v0) {
throw v0;
}
catch (Throwable var1_1) {
throw new UndeclaredThrowableException(var1_1);
}
}
public final int hashCode() {
try {
return (Integer)this.h.invoke((Object)this, m0, null);
}
catch (Error | RuntimeException v0) {
throw v0;
}
catch (Throwable var1_1) {
throw new UndeclaredThrowableException(var1_1);
}
}
static {
try {
m1 = Class.forName("java.lang.Object").getMethod("equals", Class.forName("java.lang.Object"));
m3 = Class.forName("ctgu.bytecode.proxy.service.HelloService").getMethod("sayHello", Class.forName("java.lang.String"));
m2 = Class.forName("java.lang.Object").getMethod("toString", new Class[0]);
m0 = Class.forName("java.lang.Object").getMethod("hashCode", new Class[0]);
return;
}
catch (NoSuchMethodException var1) {
throw new NoSuchMethodError(var1.getMessage());
}
catch (ClassNotFoundException var1_1) {
throw new NoClassDefFoundError(var1_1.getMessage());
}
}
}
可以看出來他實現了HelloService接口，實現了sayHello方法，實際調用的時候是使用的invocationHandler並且傳入了m3，m3實際就是靠反射拿到的接口中的sayHello方法。
m3 = Class.forName("ctgu.bytecode.proxy.service.HelloService").getMethod("sayHello", Class.forName("java.lang.String"));
4.2 CGLIB動態代理反編譯
package ctgu.bytecode.proxy.service;
import java.lang.reflect.*;
import net.sf.cglib.proxy.*;
import net.sf.cglib.core.*;
public class HelloService$$EnhancerByCGLIB$$1af19a1d implements HelloService, 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 static final Method CGLIB$finalize$0$Method;
private static final MethodProxy CGLIB$finalize$0$Proxy;
private static final Object[] CGLIB$emptyArgs;
private static final Method CGLIB$equals$1$Method;
private static final MethodProxy CGLIB$equals$1$Proxy;
private static final Method CGLIB$toString$2$Method;
private static final MethodProxy CGLIB$toString$2$Proxy;
private static final Method CGLIB$hashCode$3$Method;
private static final MethodProxy CGLIB$hashCode$3$Proxy;
private static final Method CGLIB$clone$4$Method;
private static final MethodProxy CGLIB$clone$4$Proxy;
private static final Method CGLIB$sayHello$5$Method;
private static final MethodProxy CGLIB$sayHello$5$Proxy;
static void CGLIB$STATICHOOK1() {
CGLIB$THREAD_CALLBACKS = new ThreadLocal();
CGLIB$emptyArgs = new Object[0];
final Class<?> forName = Class.forName("ctgu.bytecode.proxy.service.HelloService$$EnhancerByCGLIB$$1af19a1d");
final Class<?> forName2;
final Method[] methods = ReflectUtils.findMethods(new String[] { "finalize", "()V", "equals", "(Ljava/lang/Object;)Z", "toString", "()Ljava/lang/String;", "hashCode", "()I", "clone", "()Ljava/lang/Object;" }, (forName2 = Class.forName("java.lang.Object")).getDeclaredMethods());
CGLIB$finalize$0$Method = methods[0];
CGLIB$finalize$0$Proxy = MethodProxy.create((Class)forName2, (Class)forName, "()V", "finalize", "CGLIB$finalize$0");
CGLIB$equals$1$Method = methods[1];
CGLIB$equals$1$Proxy = MethodProxy.create((Class)forName2, (Class)forName, "(Ljava/lang/Object;)Z", "equals", "CGLIB$equals$1");
CGLIB$toString$2$Method = methods[2];
CGLIB$toString$2$Proxy = MethodProxy.create((Class)forName2, (Class)forName, "()Ljava/lang/String;", "toString", "CGLIB$toString$2");
CGLIB$hashCode$3$Method = methods[3];
CGLIB$hashCode$3$Proxy = MethodProxy.create((Class)forName2, (Class)forName, "()I", "hashCode", "CGLIB$hashCode$3");
CGLIB$clone$4$Method = methods[4];
CGLIB$clone$4$Proxy = MethodProxy.create((Class)forName2, (Class)forName, "()Ljava/lang/Object;", "clone", "CGLIB$clone$4");
final Class<?> forName3;
CGLIB$sayHello$5$Method = ReflectUtils.findMethods(new String[] { "sayHello", "(Ljava/lang/String;)Ljava/lang/String;" }, (forName3 = Class.forName("ctgu.bytecode.proxy.service.HelloService")).getDeclaredMethods())[0];
CGLIB$sayHello$5$Proxy = MethodProxy.create((Class)forName3, (Class)forName, "(Ljava/lang/String;)Ljava/lang/String;", "sayHello", "CGLIB$sayHello$5");
}
final void CGLIB$finalize$0() throws Throwable {
super.finalize();
}
protected final void finalize() throws Throwable {
MethodInterceptor cglib$CALLBACK_2;
MethodInterceptor cglib$CALLBACK_0;
if ((cglib$CALLBACK_0 = (cglib$CALLBACK_2 = this.CGLIB$CALLBACK_0)) == null) {
CGLIB$BIND_CALLBACKS(this);
cglib$CALLBACK_2 = (cglib$CALLBACK_0 = this.CGLIB$CALLBACK_0);
}
if (cglib$CALLBACK_0 != null) {
cglib$CALLBACK_2.intercept((Object)this, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$finalize$0$Method, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$emptyArgs, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$finalize$0$Proxy);
return;
}
super.finalize();
}
final boolean CGLIB$equals$1(final Object o) {
return super.equals(o);
}
public final boolean equals(final Object o) {
MethodInterceptor cglib$CALLBACK_2;
MethodInterceptor cglib$CALLBACK_0;
if ((cglib$CALLBACK_0 = (cglib$CALLBACK_2 = this.CGLIB$CALLBACK_0)) == null) {
CGLIB$BIND_CALLBACKS(this);
cglib$CALLBACK_2 = (cglib$CALLBACK_0 = this.CGLIB$CALLBACK_0);
}
if (cglib$CALLBACK_0 != null) {
final Object intercept = cglib$CALLBACK_2.intercept((Object)this, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$equals$1$Method, new Object[] { o }, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$equals$1$Proxy);
return intercept != null && (boolean)intercept;
}
return super.equals(o);
}
final String CGLIB$toString$2() {
return super.toString();
}
public final String toString() {
MethodInterceptor cglib$CALLBACK_2;
MethodInterceptor cglib$CALLBACK_0;
if ((cglib$CALLBACK_0 = (cglib$CALLBACK_2 = this.CGLIB$CALLBACK_0)) == null) {
CGLIB$BIND_CALLBACKS(this);
cglib$CALLBACK_2 = (cglib$CALLBACK_0 = this.CGLIB$CALLBACK_0);
}
if (cglib$CALLBACK_0 != null) {
return (String)cglib$CALLBACK_2.intercept((Object)this, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$toString$2$Method, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$emptyArgs, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$toString$2$Proxy);
}
return super.toString();
}
final int CGLIB$hashCode$3() {
return super.hashCode();
}
public final int hashCode() {
MethodInterceptor cglib$CALLBACK_2;
MethodInterceptor cglib$CALLBACK_0;
if ((cglib$CALLBACK_0 = (cglib$CALLBACK_2 = this.CGLIB$CALLBACK_0)) == null) {
CGLIB$BIND_CALLBACKS(this);
cglib$CALLBACK_2 = (cglib$CALLBACK_0 = this.CGLIB$CALLBACK_0);
}
if (cglib$CALLBACK_0 != null) {
final Object intercept = cglib$CALLBACK_2.intercept((Object)this, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$hashCode$3$Method, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$emptyArgs, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$hashCode$3$Proxy);
return (intercept == null) ? 0 : ((Number)intercept).intValue();
}
return super.hashCode();
}
final Object CGLIB$clone$4() throws CloneNotSupportedException {
return super.clone();
}
protected final Object clone() throws CloneNotSupportedException {
MethodInterceptor cglib$CALLBACK_2;
MethodInterceptor cglib$CALLBACK_0;
if ((cglib$CALLBACK_0 = (cglib$CALLBACK_2 = this.CGLIB$CALLBACK_0)) == null) {
CGLIB$BIND_CALLBACKS(this);
cglib$CALLBACK_2 = (cglib$CALLBACK_0 = this.CGLIB$CALLBACK_0);
}
if (cglib$CALLBACK_0 != null) {
return cglib$CALLBACK_2.intercept((Object)this, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$clone$4$Method, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$emptyArgs, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$clone$4$Proxy);
}
return super.clone();
}
final String CGLIB$sayHello$5(final String s) {
return super.sayHello(s);
}
public final String sayHello(final String s) {
MethodInterceptor cglib$CALLBACK_2;
MethodInterceptor cglib$CALLBACK_0;
if ((cglib$CALLBACK_0 = (cglib$CALLBACK_2 = this.CGLIB$CALLBACK_0)) == null) {
CGLIB$BIND_CALLBACKS(this);
cglib$CALLBACK_2 = (cglib$CALLBACK_0 = this.CGLIB$CALLBACK_0);
}
if (cglib$CALLBACK_0 != null) {
return (String)cglib$CALLBACK_2.intercept((Object)this, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$sayHello$5$Method, new Object[] { s }, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$sayHello$5$Proxy);
}
return super.sayHello(s);
}
public static MethodProxy CGLIB$findMethodProxy(final Signature signature) {
final String string = signature.toString();
switch (string.hashCode()) {
case -1816210712: {
if (string.equals("sayHello(Ljava/lang/String;)Ljava/lang/String;")) {
return HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$sayHello$5$Proxy;
}
break;
}
case -1574182249: {
if (string.equals("finalize()V")) {
return HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$finalize$0$Proxy;
}
break;
}
case -508378822: {
if (string.equals("clone()Ljava/lang/Object;")) {
return HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$clone$4$Proxy;
}
break;
}
case 1826985398: {
if (string.equals("equals(Ljava/lang/Object;)Z")) {
return HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$equals$1$Proxy;
}
break;
}
case 1913648695: {
if (string.equals("toString()Ljava/lang/String;")) {
return HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$toString$2$Proxy;
}
break;
}
case 1984935277: {
if (string.equals("hashCode()I")) {
return HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$hashCode$3$Proxy;
}
break;
}
}
return null;
}
public HelloService$$EnhancerByCGLIB$$1af19a1d() {
CGLIB$BIND_CALLBACKS(this);
}
public static void CGLIB$SET_THREAD_CALLBACKS(final Callback[] array) {
HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$THREAD_CALLBACKS.set(array);
}
public static void CGLIB$SET_STATIC_CALLBACKS(final Callback[] cglib$STATIC_CALLBACKS) {
CGLIB$STATIC_CALLBACKS = cglib$STATIC_CALLBACKS;
}
private static final void CGLIB$BIND_CALLBACKS(final Object o) {
final HelloService$$EnhancerByCGLIB$$1af19a1d helloService$$EnhancerByCGLIB$$1af19a1d = (HelloService$$EnhancerByCGLIB$$1af19a1d)o;
if (!helloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$BOUND) {
helloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$BOUND = true;
Object o2;
if ((o2 = HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$THREAD_CALLBACKS.get()) != null || (o2 = HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$STATIC_CALLBACKS) != null) {
helloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$CALLBACK_0 = (MethodInterceptor)((Callback[])o2)[0];
}
}
}
public Object newInstance(final Callback[] array) {
CGLIB$SET_THREAD_CALLBACKS(array);
final HelloService$$EnhancerByCGLIB$$1af19a1d helloService$$EnhancerByCGLIB$$1af19a1d = new HelloService$$EnhancerByCGLIB$$1af19a1d();
CGLIB$SET_THREAD_CALLBACKS(null);
return helloService$$EnhancerByCGLIB$$1af19a1d;
}
public Object newInstance(final Callback callback) {
CGLIB$SET_THREAD_CALLBACKS(new Callback[] { callback });
final HelloService$$EnhancerByCGLIB$$1af19a1d helloService$$EnhancerByCGLIB$$1af19a1d = new HelloService$$EnhancerByCGLIB$$1af19a1d();
CGLIB$SET_THREAD_CALLBACKS(null);
return helloService$$EnhancerByCGLIB$$1af19a1d;
}
public Object newInstance(final Class[] array, final Object[] array2, final Callback[] array3) {
CGLIB$SET_THREAD_CALLBACKS(array3);
switch (array.length) {
case 0: {
final HelloService$$EnhancerByCGLIB$$1af19a1d helloService$$EnhancerByCGLIB$$1af19a1d = new HelloService$$EnhancerByCGLIB$$1af19a1d();
CGLIB$SET_THREAD_CALLBACKS(null);
return helloService$$EnhancerByCGLIB$$1af19a1d;
}
default: {
throw new IllegalArgumentException("Constructor not found");
}
}
}
public Callback getCallback(final int n) {
CGLIB$BIND_CALLBACKS(this);
Object cglib$CALLBACK_0 = null;
switch (n) {
case 0: {
cglib$CALLBACK_0 = this.CGLIB$CALLBACK_0;
break;
}
default: {
cglib$CALLBACK_0 = null;
break;
}
}
return (Callback)cglib$CALLBACK_0;
}
public void setCallback(final int n, final Callback callback) {
switch (n) {
case 0: {
this.CGLIB$CALLBACK_0 = (MethodInterceptor)callback;
break;
}
}
}
public Callback[] getCallbacks() {
CGLIB$BIND_CALLBACKS(this);
return new Callback[] { this.CGLIB$CALLBACK_0 };
}
public void setCallbacks(final Callback[] array) {
this.CGLIB$CALLBACK_0 = (MethodInterceptor)array[0];
}
static {
CGLIB$STATICHOOK1();
}
}
生成的類同樣實現了 HelloService接口並且實現了Factory接口，Factory接口如下：
public interface Factory {
Object newInstance(Callback callback);
Object newInstance(Callback[] callbacks);
Object newInstance(Class[] types, Object[] args, Callback[] callbacks);
Callback getCallback(int index);
void setCallback(int index, Callback callback);
void setCallbacks(Callback[] callbacks);
Callback[] getCallbacks();
}
直接看生成的sayHello實現
public final String sayHello(final String s) {
MethodInterceptor cglib$CALLBACK_2;
MethodInterceptor cglib$CALLBACK_0;
if ((cglib$CALLBACK_0 = (cglib$CALLBACK_2 = this.CGLIB$CALLBACK_0)) == null) {
CGLIB$BIND_CALLBACKS(this);
cglib$CALLBACK_2 = (cglib$CALLBACK_0 = this.CGLIB$CALLBACK_0);
}
if (cglib$CALLBACK_0 != null) {
return (String)cglib$CALLBACK_2.intercept((Object)this, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$sayHello$5$Method, new Object[] { s }, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$sayHello$5$Proxy);
}
return super.sayHello(s);
}
可以看到cglib$CALLBACK_0是通過CGLIB$BIND_CALLBACKS(this)完成的,glib$CALLBACK_2跟glib$CALLBACK_2是一個東西。
再看CGLIB$BIND_CALLBACKS(this)做了啥
private static final void CGLIB$BIND_CALLBACKS(final Object o) {
final HelloService$$EnhancerByCGLIB$$1af19a1d helloService$$EnhancerByCGLIB$$1af19a1d = (HelloService$$EnhancerByCGLIB$$1af19a1d)o;
if (!helloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$BOUND) {
helloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$BOUND = true;
Object o2;
if ((o2 = HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$THREAD_CALLBACKS.get()) != null || (o2 = HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$STATIC_CALLBACKS) != null) {
helloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$CALLBACK_0 = (MethodInterceptor)((Callback[])o2)[0];
}
}
}
CGLIB$CALLBACK_0是CGLIB$THREAD_CALLBACKS.get()或者CGLIB$STATIC_CALLBACKS，
CGLIB$THREAD_CALLBACKS是一個threadlocal的成員變量。
CGLIB$THREAD_CALLBACKS是由下面的CGLIB$SET_THREAD_CALLBACKS方法來設置的，
public static void CGLIB$SET_THREAD_CALLBACKS(final Callback[] array) {
HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$THREAD_CALLBACKS.set(array);
}
這個方法被Factory接口的newInstance調用
public Object newInstance(final Callback[] array) {
CGLIB$SET_THREAD_CALLBACKS(array);
final HelloService$$EnhancerByCGLIB$$1af19a1d helloService$$EnhancerByCGLIB$$1af19a1d = new HelloService$$EnhancerByCGLIB$$1af19a1d();
CGLIB$SET_THREAD_CALLBACKS(null);
return helloService$$EnhancerByCGLIB$$1af19a1d;
}
public Object newInstance(final Callback callback) {
CGLIB$SET_THREAD_CALLBACKS(new Callback[] { callback });
final HelloService$$EnhancerByCGLIB$$1af19a1d helloService$$EnhancerByCGLIB$$1af19a1d = new HelloService$$EnhancerByCGLIB$$1af19a1d();
CGLIB$SET_THREAD_CALLBACKS(null);
return helloService$$EnhancerByCGLIB$$1af19a1d;
}
我看不懂的就是他為什么 CGLIB$SET_THREAD_CALLBACKS(array); 之后又 CGLIB$SET_THREAD_CALLBACKS(null); ???反編譯的問題?
對於CGLIB$STATIC_CALLBACKS是由
public static void CGLIB$SET_STATIC_CALLBACKS(final Callback[] cglib$STATIC_CALLBACKS) {
CGLIB$STATIC_CALLBACKS = cglib$STATIC_CALLBACKS;
}
這個方法賦值上的，但是我沒找到調用的地方。
最后看實際上執行的方法的地方，就是掉的intercepter的intercept方法。
(String)cglib$CALLBACK_2.intercept((Object)this, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$sayHello$5$Method, new Object[] { s }, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$sayHello$5$Proxy);
最后一個參數是個MethodProxy
CGLIB$sayHello$5$Proxy = MethodProxy.create((Class)forName3, (Class)forName, "(Ljava/lang/String;)Ljava/lang/String;", "sayHello", "CGLIB$sayHello$5");
我猜應該是對方法生成了一個代理
final String CGLIB$sayHello$5(final String s) {
return super.sayHello(s);
}
關於這個cglib生成的字節碼好多反編譯工具都不能解析。不保證上面生成代碼的正確性