[TOC]
1. 定义
代理模式是指为其他对象提供一种代理,以控制对这个对象的访问
代理对象在客服端和目标对象之间起到中介作用
2. 适用场景
- 保护目标对象
- 增强目标对象
3. 分类
- 静态代理
- JDK 动态代理
- CGLIB 动态代理
3.1 静态代理
3.1.1 代码实现
- 定义被代理类
public interface Person {
/**
* 相亲
*/
void findLove();
}
public class Son implements Person {
@Override
public void findLove() {
System.out.println("寻找伴侣要求: 肤白貌美大长腿");
}
}
- 代理类
public class Father implements Person {
private Son son;
public Father(Son son) {
this.son = son;
}
@Override
public void findLove() {
this.before();
this.son.findLove();
this.after();
}
/**
* 增强目标对象
* 执行之前
*/
private void before(){
System.out.println("父亲正在帮儿子物色对象");
}
/**
* 增强目标对象
* 执行之后
*/
private void after(){
System.out.println("双方父母同意,确定关系");
}
}
- 测试类
public class FatherProxyTest {
public static void main(String[] args) {
Father father = new Father(new Son());
father.findLove();
}
}
-
运行结果
image
3.1.2 总结
被代理类 Son 当前只有 findLove 需求,后期增加 findJob 等更多的需求,Father 也要增加对应的代码,不符合开闭原则
代理类与被代理类中间存在联系,代理类不能对所有的类服务
3.1.3 扩展--分库分表
- Order 订单实体
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Order {
private Object orderInfo;
private Long createTime;
private String id;
}
- OrderDao 持久层
public class OrderDao {
public int insert(Order order) {
System.out.println("OrderDao 创建 Order 成功!");
return 1;
}
}
- IOrderService 接口
public interface IOrderService {
int createOrder(Order order);
}
- OrderService 实现类
public class OrderService implements IOrderService {
private OrderDao orderDao;
public OrderService() {
//如果使用 Spring 应该是自动注入的
//我们为了使用方便,在构造方法中将 orderDao 直接初始化了
orderDao = new OrderDao();
}
@Override
public int createOrder(Order order) {
System.out.println("OrderService 调用 orderDao 创建订单");
return orderDao.insert(order);
}
}
- ThreadLocal 的单例实现 DynamicDataSourceEntry 类
接下来使用静态代理,主要完成的功能是,根据订单创建时间自动按年进行分库.根据开闭原则,原来写好的逻辑我们不去修改,通过代理对象来完成.先创建数据源路由对象,我们使用 ThreadLocal 的单例实现 DynamicDataSourceEntry 类
/**
* 动态切换数据源
*/
public class DynamicDataSourceEntry {
// 默认数据源
public final static String DEFAULT_SOURCE = null;
private final static ThreadLocal local = new ThreadLocal();
private DynamicDataSourceEntry() {
}
/**
* 清空数据源
*/
public static void clear() {
local.remove();
}
/**
* 获取当前正在使用的数据源名字
*/
public static String get() {
return local.get();
}
/**
* 还原当前切面的数据源
*/
public static void restore() {
local.set(DEFAULT_SOURCE);
}
/**
* 设置已知名字的数据源
*/
public static void set(String source) {
local.set(source);
}
/**
* 根据年份动态设置数据源
*/
public static void set(int year) {
local.set("DB_" + year);
}
}
- 创建切换数据源的代理 OrderServiceSaticProxy 类
public class OrderServiceStaticProxy implements IOrderService {
private SimpleDateFormat yearFormat = new SimpleDateFormat("yyyy");
private IOrderService orderService;
public OrderServiceStaticProxy(IOrderService orderService) {
this.orderService = orderService;
}
public int createOrder(Order order) {
before();
Long time = order.getCreateTime();
Integer dbRouter = Integer.valueOf(yearFormat.format(new Date(time)));
System.out.println("静态代理类自动分配到[DB_" + dbRouter + "]数据源处理数据");
DynamicDataSourceEntry.set(dbRouter);
orderService.createOrder(order);
after();
return 0;
}
private void before() {
System.out.println("Proxy before method.");
}
private void after() {
System.out.println("Proxy after method.");
}
}
- 测试代码
public class OrderTest {
public static void main(String[] args) {
try {
Order order = new Order();
order.setCreateTime(System.currentTimeMillis());
SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd");
Date date = sdf.parse("2017/02/01");
order.setCreateTime(date.getTime());
IOrderService orderService = new OrderServiceStaticProxy(new OrderService());
orderService.createOrder(order);
} catch (Exception e) {
e.printStackTrace();
}
}
}
-
运行结果
image
3.2 JDK 动态代理
3.2.1 实现原理
- 拿到被代理类的引用,并且获取它的所有接口(反射获取)
- JDKProxy 类重新生成一个新的类,实现了被代理类所有接口的方法
- 动态生成 java 代码,把增强逻辑加入到新生成代码中
- 编译生成新的 java 代码的 class 文件
- 加载并重新运行新的 class,得到的类就是全新类
3.2.2 代码实现
- 被代理类
public interface Person {
/**
* 相亲
*/
void findLove();
}
public class Girl implements Person {
@Override
public void findLove() {
System.out.println("寻找对象要求:");
System.out.println("身高 180");
System.out.println("有钱");
System.out.println("有六块腹肌");
}
}
- 代理类
public class JDKMeipo implements InvocationHandler {
private Person person;
public Object getInstance(Person person) {
this.person = person;
Class clazz = this.person.getClass();
return Proxy.newProxyInstance(clazz.getClassLoader(), clazz.getInterfaces(), this);
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
before();
Object object = method.invoke(this.person, args);
before();
return object;
}
/**
* 增强目标对象
* 执行之前
*/
private void before(){
System.out.println("我是媒婆,已经收到你的诉求");
System.out.println("正在物色对象");
}
/**
* 增强目标对象
* 执行之后
*/
private void after(){
System.out.println("相亲完成,确认双方意见");
}
}
- 测试类
public class JDKProxyTest {
public static void main(String[] args) {
Person person = (Person) new JDKMeipo().getInstance(new Girl());
person.findLove();
}
}
-
运行结果
image
3.2.3 总结
- 被代理类 Girl 在 findLove 功能的基础上增加其他需求,代理类 JDKMeiPo 不需要修改代码
- 代理类 JDKMeiPo 不仅可以代理 Girl 类,也可以代理其他类
3.2.4 拓展
再来看数据源动态路由业务,帮助小伙伴们对动态代理加深一下印象.创建动态代理的类 OrderServiceDynamicProxy,代码如下
public class OrderServiceDynamicProxy implements InvocationHandler {
private SimpleDateFormat yearFormat = new SimpleDateFormat("yyyy");
private Object target;
public Object getInstance(Object target){
this.target = target;
Class clazz = target.getClass();
return Proxy.newProxyInstance(clazz.getClassLoader(),clazz.getInterfaces(),this);
}
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
before(args[0]);
Object object = method.invoke(target,args);
after();
return object;
}
private void before(Object target){
try {
System.out.println("Proxy before method.");
Long time = (Long) target.getClass().getMethod("getCreateTime").invoke(target);
Integer dbRouter = Integer.valueOf(yearFormat.format(new Date(time)));
System.out.println("静态代理类自动分配到【DB_" + dbRouter + "】数据源处理数据。");
DynamicDataSourceEntry.set(dbRouter);
}catch (Exception e){
e.printStackTrace();
}
}
private void after(){
System.out.println("Proxy after method.");
}
}
动态代理实现之后,我们不仅能实现 Order 的数据源动态路由,还可以实现其他任何类的数据源路由.当然,有比较重要的约定,必须要求实现 getCreateTime()方法,因为路由规则是根据时间来运算的.当然,我们可以通过接口规范来达到约束的目的
4. 自己实现 JDK 动态代理
4.1 JDK 动态代理实现步骤
不仅知其然,还得知其所以然,既然 JDKProxy 功能如此强大,那么它是如何实现的呢?
我们现在来探究一下原理,并模仿 JDKProxy 自己动手写一个属于自己的动态代理
我们都知道 JDKProxy 采用字节重组,重新生的对象来替代原始的对象以达到动态代理的目的
JDKProxy 生成对象的步骤如下:
- 拿到被代理类的引用,并且获取它的所有接口(反射获取)
- JDKProxy 类重新生成一个新的类,实现了被代理类所有接口的方法
- 动态生成 java 代码,把增强逻辑加入到新生成代码中
- 编译生成新的 java 代码的 class 文件
- 加载并重新运行新的 class,得到的类就是全新类
以上这个过程就叫字节码重组.JDK 中有一个规范,在 ClassPath 下只要是$开头的 class 文件一般都是自动生成的.那么我们有没有办法看到代替后的对象的真容呢?
做一个这样测试,我们从内存中的对象字节码通过文件流输出到一个新的 class 文件,然后利用反编译工具查看 class 的源代码
4.2 jdk 动态代理原理解析
在代理类 JDKMeipo 中传入 Gir 类
Personperson=(Person)newJDKMeipo().getInstance(newGirl());
,得到 Person 类是一个全新的类$Proxy0
把
$Proxy0
这个对象输出到文件$Proxy0.class
中,可以看到这个$Proxy
类的代码
public class JDKProxyTest {
public static void main(String[] args) {
Person person = (Person) new JDKMeipo().getInstance(new Girl());
person.findLove();
byte[] bytes = ProxyGenerator.generateProxyClass("$Proxy0", new Class[]{Person.class});
try (FileOutputStream fileOutputStream = new FileOutputStream("./proxy/$Proxy0.class")) {
fileOutputStream.write(bytes);
} catch (Exception e) {
e.printStackTrace();
}
}
}
可以看到Methodm3
对应就是 Girl 类中的 findLove 方法
//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//
import com.zhunongyun.toalibaba.designpatterns.proxy.Person;
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 Person {
private static Method m1;
private static Method m3;
private static Method m2;
private static Method m0;
public $Proxy0(InvocationHandler var1) throws {
super(var1);
}
public final boolean equals(Object var1) throws {
try {
return (Boolean)super.h.invoke(this, m1, new Object[]{var1});
} catch (RuntimeException | Error var3) {
throw var3;
} catch (Throwable var4) {
throw new UndeclaredThrowableException(var4);
}
}
public final void findLove() throws {
try {
super.h.invoke(this, m3, (Object[])null);
} catch (RuntimeException | Error var2) {
throw var2;
} catch (Throwable var3) {
throw new UndeclaredThrowableException(var3);
}
}
public final String toString() throws {
try {
return (String)super.h.invoke(this, m2, (Object[])null);
} catch (RuntimeException | Error var2) {
throw var2;
} catch (Throwable var3) {
throw new UndeclaredThrowableException(var3);
}
}
public final int hashCode() throws {
try {
return (Integer)super.h.invoke(this, m0, (Object[])null);
} catch (RuntimeException | Error var2) {
throw var2;
} catch (Throwable var3) {
throw new UndeclaredThrowableException(var3);
}
}
static {
try {
m1 = Class.forName("java.lang.Object").getMethod("equals", Class.forName("java.lang.Object"));
m3 = Class.forName("com.zhunongyun.toalibaba.designpatterns.proxy.Person").getMethod("findLove");
m2 = Class.forName("java.lang.Object").getMethod("toString");
m0 = Class.forName("java.lang.Object").getMethod("hashCode");
} catch (NoSuchMethodException var2) {
throw new NoSuchMethodError(var2.getMessage());
} catch (ClassNotFoundException var3) {
throw new NoClassDefFoundError(var3.getMessage());
}
}
}
我们发现$Proxy0 继承了 Proxy 类,同时还实现了我们的 Person 接口,而且重写了 findLove()等方法.而且在静态块中用反射查找到了目标对象的所有方法,而且保存了所有方法的引用,在重写的方法用反射调用目标对象的方法.
小伙伴们此时一定在好奇,这些代码是哪里来的呢?其实是 JDK 帮我们自动生成的.现在我们不依赖 JDK 自己来动态生成源代码,动态完成编译,然后替代目标对象并执行
4.3 高仿真 JDKProxy 手写实现
- 1.被代理类
public class Girl implements Person {
@Override
public void findLove() {
System.out.println("寻找对象要求:");
System.out.println("身高 180");
System.out.println("有钱");
System.out.println("有六块腹肌");
}
}
- 2.代理类
public class MyMeipo implements MyInvocationHandler {
private Person person;
public Object getInstance(Person person) {
this.person = person;
Class clazz = this.person.getClass();
return MyProxy.newProxyInstance(new MyClassLoader(), clazz.getInterfaces(), this);
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) {
Object object = null;
try {
before();
object = method.invoke(this.person, args);
after();
} catch (Exception e) {
e.printStackTrace();
}
return object;
}
/**
* 增强目标对象
* 执行之前
*/
private void before(){
System.out.println("我是媒婆,已经收到你的诉求");
System.out.println("正在物色对象");
}
/**
* 增强目标对象
* 执行之后
*/
private void after(){
System.out.println("相亲完成,确认双方意见");
}
}
- 3.自定义类加载器 ClassLoader
public class MyClassLoader extends ClassLoader {
private File classPathFile;
public MyClassLoader() {
String classPath = MyClassLoader.class.getResource("").getPath();
classPathFile = new File(classPath);
}
@Override
public Class findClass(String name) throws ClassNotFoundException {
String className = MyClassLoader.class.getPackage().getName() + "." +name;
if (classPathFile != null) {
File file = new File(classPathFile, name + ".class");
try (FileInputStream fileInputStream = new FileInputStream(file);
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();) {
byte[] buff = new byte[1024];
int len;
while((len=fileInputStream.read(buff))!=-1){
outputStream.write(buff, 0, len);
}
return defineClass(className, outputStream.toByteArray(), 0, outputStream.size());
}catch(Exception e){
e.printStackTrace();
}
}
return null;
}
}
- 4.自定义 InvacationHandler
public interface MyInvocationHandler {
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable;
}
- 5.自定义代理类 Proxy
public class MyProxy {
public static final String LN = "\r\n";
public static Object newProxyInstance(MyClassLoader myClassLoader, Class[] interfaces, MyInvocationHandler h) {
try{
// 1 动态生成 java 源码
String src = generateSrc(interfaces);
// 2 将源码输出到 java 文件中
String filePath = MyProxy.class.getResource("").getPath();
File f = new File(filePath + "$Proxy0.java");
FileWriter fw = new FileWriter(f);
fw.write(src);
fw.flush();
fw.close();
//3、将 java 文件编译成 class 文件
JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
StandardJavaFileManager manage = compiler.getStandardFileManager(null,null,null);
Iterable iterable = manage.getJavaFileObjects(f);
JavaCompiler.CompilationTask task = compiler.getTask(null,manage,null,null,null,iterable);
task.call();
manage.close();
//4、将 class 加载进 jvm
Class proxyClass=myClassLoader.findClass("$Proxy0");
f.delete();
//5、返回代理类对象
Constructor constructor = proxyClass.getConstructor(MyInvocationHandler.class);
return constructor.newInstance(h);
}catch(Exception e){
e.printStackTrace();
}
return null;
}
private static String generateSrc(Class[] interfaces) {
// TODO Auto-generated method stub
StringBuffer sb = new StringBuffer();
sb.append("package com.zhunongyun.toalibaba.designpatterns.proxy.myproxy;").append(LN);
sb.append("import java.lang.reflect.Method;").append(LN);
sb.append("public class $Proxy0 implements " + interfaces[0].getName() + "{").append(LN);
sb.append("private MyInvocationHandler h;").append(LN);
sb.append("public $Proxy0(MyInvocationHandler h) { ").append(LN);
sb.append("this.h = h;").append(LN);
sb.append("}").append(LN);
for (Method m : interfaces[0].getMethods()) {
sb.append("public " + m.getReturnType().getName() + " " + m.getName() + "() {").append(LN);
sb.append("try{").append(LN);
sb.append("Method m = " + interfaces[0].getName() + ".class.getMethod(\"" + m.getName() + "\",new Class[]{});").append(LN);
sb.append("this.h.invoke(this,m,null);").append(LN);
sb.append("}catch(Throwable e){").append(LN);
sb.append("e.printStackTrace();").append(LN);
sb.append("}").append(LN);
sb.append("}").append(LN);
}
sb.append("}").append(LN);
return sb.toString();
}
}
- 6.测试类
public class MyProxyTest {
public static void main(String[] args) {
Person person = (Person) new MyMeipo().getInstance(new Girl());
person.findLove();
}
}
5. CGlib 动态代理
- CGlib 通过继承被代理类,并覆盖被代理类的方法
- CGlib 可以代理任意一个普通的类,没有任何要求
- CGlib 生成代理逻辑更加复杂,调用效率更高,生成一个包含了所有的逻辑的 FastClass,不再需要反射调用
- CGlib 代理有坑,不能代理 final 方法
5.1 代码实现
- 1.被代理类
public class NewGirl {
public void findLove() {
System.out.println("寻找对象要求:");
System.out.println("身高 180");
System.out.println("有钱");
System.out.println("有六块腹肌");
}
}
- 2.CGLib 代理类
public class CGlibMeipo implements MethodInterceptor {
public Object getInstance(Class clazz) throws Exception {
Enhancer enhancer = new Enhancer();
enhancer.setSuperclass(clazz);
enhancer.setCallback(this);
return enhancer.create();
}
@Override
public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
before();
Object object = methodProxy.invokeSuper(o, objects);
after();
return object;
}
/**
* 增强目标对象
* 执行之前
*/
private void before(){
System.out.println("我是媒婆,已经收到你的诉求");
System.out.println("正在物色对象");
}
/**
* 增强目标对象
* 执行之后
*/
private void after(){
System.out.println("相亲完成,确认双方意见");
}
}
- 3.测试类
public class CGlibProxyTest {
public static void main(String[] args) {
// 把 CGlib 生成的代码输出到文件中
System.setProperty(DebuggingClassWriter.DEBUG_LOCATION_PROPERTY, CGlibProxyTest.class.getResource("").getPath());
try {
NewGirl newGirl = (NewGirl) new CGlibMeipo().getInstance(NewGirl.class);
newGirl.findLove();
} catch (Exception e) {
e.printStackTrace();
}
}
}
CGLib 代理的目标对象不需要实现任何接口,它是通过动态继承目标对象实现的动态代理
5.2 CGlib 工作原理分析
在 CGlib 代理测试类中输出生成的代码到磁盘文件,生成了以下三个 class 文件
- NewGirl2a25c1b42393400d.class
- NewGirl2a25c1b4.class
- NewGirl1cf5df8b.class
NewGirl2a25c1b4.class 是 CGLib 生成的代理类,继承了 NewGirl 类
反编译这三个 class 文件详情如下
重写了 NewGirl 类的所有方法,我们通过代理类的源码可以看到,代理类会获得所有在父类继承来的方法,并且会有 MethodProxy 与之对应,比如 MethodCGLIB0findLoveProxy;这些方法在代理类的 findLove()中都有调用
- 1.NewGirl$$EnhancerByCGLIB$$2a25c1b4.class
//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//
package com.zhunongyun.toalibaba.designpatterns.proxy.cglibproxy;
import java.lang.reflect.Method;
import org.springframework.cglib.core.ReflectUtils;
import org.springframework.cglib.core.Signature;
import org.springframework.cglib.proxy.Callback;
import org.springframework.cglib.proxy.Factory;
import org.springframework.cglib.proxy.MethodInterceptor;
import org.springframework.cglib.proxy.MethodProxy;
public class NewGirl$$EnhancerByCGLIB$$2a25c1b4 extends NewGirl implements Factory {
private boolean CGLIB$BOUND;
public static Object CGLIB$FACTORY_DATA;
private static final ThreadLocal CGLIB$THREAD_CALLBACKS;
private static final Callback[] CGLIB$STATIC_CALLBACKS;
private MethodInterceptor CGLIB$CALLBACK_0;
private static Object CGLIB$CALLBACK_FILTER;
private static final Method CGLIB$findLove$0$Method;
private static final MethodProxy CGLIB$findLove$0$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;
static void CGLIB$STATICHOOK1() {
CGLIB$THREAD_CALLBACKS = new ThreadLocal();
CGLIB$emptyArgs = new Object[0];
Class var0 = Class.forName("com.zhunongyun.toalibaba.designpatterns.proxy.cglibproxy.NewGirl$$EnhancerByCGLIB$$2a25c1b4");
Class var1;
Method[] var10000 = ReflectUtils.findMethods(new String[]{"equals", "(Ljava/lang/Object;)Z", "toString", "()Ljava/lang/String;", "hashCode", "()I", "clone", "()Ljava/lang/Object;"}, (var1 = Class.forName("java.lang.Object")).getDeclaredMethods());
CGLIB$equals$1$Method = var10000[0];
CGLIB$equals$1$Proxy = MethodProxy.create(var1, var0, "(Ljava/lang/Object;)Z", "equals", "CGLIB$equals$1");
CGLIB$toString$2$Method = var10000[1];
CGLIB$toString$2$Proxy = MethodProxy.create(var1, var0, "()Ljava/lang/String;", "toString", "CGLIB$toString$2");
CGLIB$hashCode$3$Method = var10000[2];
CGLIB$hashCode$3$Proxy = MethodProxy.create(var1, var0, "()I", "hashCode", "CGLIB$hashCode$3");
CGLIB$clone$4$Method = var10000[3];
CGLIB$clone$4$Proxy = MethodProxy.create(var1, var0, "()Ljava/lang/Object;", "clone", "CGLIB$clone$4");
CGLIB$findLove$0$Method = ReflectUtils.findMethods(new String[]{"findLove", "()V"}, (var1 = Class.forName("com.zhunongyun.toalibaba.designpatterns.proxy.cglibproxy.NewGirl")).getDeclaredMethods())[0];
CGLIB$findLove$0$Proxy = MethodProxy.create(var1, var0, "()V", "findLove", "CGLIB$findLove$0");
}
final void CGLIB$findLove$0() {
super.findLove();
}
public final void findLove() {
MethodInterceptor var10000 = this.CGLIB$CALLBACK_0;
if (var10000 == null) {
CGLIB$BIND_CALLBACKS(this);
var10000 = this.CGLIB$CALLBACK_0;
}
if (var10000 != null) {
var10000.intercept(this, CGLIB$findLove$0$Method, CGLIB$emptyArgs, CGLIB$findLove$0$Proxy);
} else {
super.findLove();
}
}
final boolean CGLIB$equals$1(Object var1) {
return super.equals(var1);
}
public final boolean equals(Object var1) {
MethodInterceptor var10000 = this.CGLIB$CALLBACK_0;
if (var10000 == null) {
CGLIB$BIND_CALLBACKS(this);
var10000 = this.CGLIB$CALLBACK_0;
}
if (var10000 != null) {
Object var2 = var10000.intercept(this, CGLIB$equals$1$Method, new Object[]{var1}, CGLIB$equals$1$Proxy);
return var2 == null ? false : (Boolean)var2;
} else {
return super.equals(var1);
}
}
final String CGLIB$toString$2() {
return super.toString();
}
public final String toString() {
MethodInterceptor var10000 = this.CGLIB$CALLBACK_0;
if (var10000 == null) {
CGLIB$BIND_CALLBACKS(this);
var10000 = this.CGLIB$CALLBACK_0;
}
return var10000 != null ? (String)var10000.intercept(this, CGLIB$toString$2$Method, CGLIB$emptyArgs, CGLIB$toString$2$Proxy) : super.toString();
}
final int CGLIB$hashCode$3() {
return super.hashCode();
}
public final int hashCode() {
MethodInterceptor var10000 = this.CGLIB$CALLBACK_0;
if (var10000 == null) {
CGLIB$BIND_CALLBACKS(this);
var10000 = this.CGLIB$CALLBACK_0;
}
if (var10000 != null) {
Object var1 = var10000.intercept(this, CGLIB$hashCode$3$Method, CGLIB$emptyArgs, CGLIB$hashCode$3$Proxy);
return var1 == null ? 0 : ((Number)var1).intValue();
} else {
return super.hashCode();
}
}
final Object CGLIB$clone$4() throws CloneNotSupportedException {
return super.clone();
}
protected final Object clone() throws CloneNotSupportedException {
MethodInterceptor var10000 = this.CGLIB$CALLBACK_0;
if (var10000 == null) {
CGLIB$BIND_CALLBACKS(this);
var10000 = this.CGLIB$CALLBACK_0;
}
return var10000 != null ? var10000.intercept(this, CGLIB$clone$4$Method, CGLIB$emptyArgs, CGLIB$clone$4$Proxy) : super.clone();
}
public static MethodProxy CGLIB$findMethodProxy(Signature var0) {
String var10000 = var0.toString();
switch(var10000.hashCode()) {
case -508378822:
if (var10000.equals("clone()Ljava/lang/Object;")) {
return CGLIB$clone$4$Proxy;
}
break;
case 1192015562:
if (var10000.equals("findLove()V")) {
return CGLIB$findLove$0$Proxy;
}
break;
case 1826985398:
if (var10000.equals("equals(Ljava/lang/Object;)Z")) {
return CGLIB$equals$1$Proxy;
}
break;
case 1913648695:
if (var10000.equals("toString()Ljava/lang/String;")) {
return CGLIB$toString$2$Proxy;
}
break;
case 1984935277:
if (var10000.equals("hashCode()I")) {
return CGLIB$hashCode$3$Proxy;
}
}
return null;
}
public NewGirl$$EnhancerByCGLIB$$2a25c1b4() {
CGLIB$BIND_CALLBACKS(this);
}
public static void CGLIB$SET_THREAD_CALLBACKS(Callback[] var0) {
CGLIB$THREAD_CALLBACKS.set(var0);
}
public static void CGLIB$SET_STATIC_CALLBACKS(Callback[] var0) {
CGLIB$STATIC_CALLBACKS = var0;
}
private static final void CGLIB$BIND_CALLBACKS(Object var0) {
NewGirl$$EnhancerByCGLIB$$2a25c1b4 var1 = (NewGirl$$EnhancerByCGLIB$$2a25c1b4)var0;
if (!var1.CGLIB$BOUND) {
var1.CGLIB$BOUND = true;
Object var10000 = CGLIB$THREAD_CALLBACKS.get();
if (var10000 == null) {
var10000 = CGLIB$STATIC_CALLBACKS;
if (var10000 == null) {
return;
}
}
var1.CGLIB$CALLBACK_0 = (MethodInterceptor)((Callback[])var10000)[0];
}
}
public Object newInstance(Callback[] var1) {
CGLIB$SET_THREAD_CALLBACKS(var1);
NewGirl$$EnhancerByCGLIB$$2a25c1b4 var10000 = new NewGirl$$EnhancerByCGLIB$$2a25c1b4();
CGLIB$SET_THREAD_CALLBACKS((Callback[])null);
return var10000;
}
public Object newInstance(Callback var1) {
CGLIB$SET_THREAD_CALLBACKS(new Callback[]{var1});
NewGirl$$EnhancerByCGLIB$$2a25c1b4 var10000 = new NewGirl$$EnhancerByCGLIB$$2a25c1b4();
CGLIB$SET_THREAD_CALLBACKS((Callback[])null);
return var10000;
}
public Object newInstance(Class[] var1, Object[] var2, Callback[] var3) {
CGLIB$SET_THREAD_CALLBACKS(var3);
NewGirl$$EnhancerByCGLIB$$2a25c1b4 var10000 = new NewGirl$$EnhancerByCGLIB$$2a25c1b4;
switch(var1.length) {
case 0:
var10000.();
CGLIB$SET_THREAD_CALLBACKS((Callback[])null);
return var10000;
default:
throw new IllegalArgumentException("Constructor not found");
}
}
public Callback getCallback(int var1) {
CGLIB$BIND_CALLBACKS(this);
MethodInterceptor var10000;
switch(var1) {
case 0:
var10000 = this.CGLIB$CALLBACK_0;
break;
default:
var10000 = null;
}
return var10000;
}
public void setCallback(int var1, Callback var2) {
switch(var1) {
case 0:
this.CGLIB$CALLBACK_0 = (MethodInterceptor)var2;
default:
}
}
public Callback[] getCallbacks() {
CGLIB$BIND_CALLBACKS(this);
return new Callback[]{this.CGLIB$CALLBACK_0};
}
public void setCallbacks(Callback[] var1) {
this.CGLIB$CALLBACK_0 = (MethodInterceptor)var1[0];
}
static {
CGLIB$STATICHOOK1();
}
}
- 2.NewGirl$$EnhancerByCGLIB$$2a25c1b4$$FastClassByCGLIB$$2393400d.class
//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//
package com.zhunongyun.toalibaba.designpatterns.proxy.cglibproxy;
import com.zhunongyun.toalibaba.designpatterns.proxy.cglibproxy.NewGirl..EnhancerByCGLIB..2a25c1b4;
import java.lang.reflect.InvocationTargetException;
import org.springframework.cglib.core.Signature;
import org.springframework.cglib.proxy.Callback;
import org.springframework.cglib.reflect.FastClass;
public class NewGirl$$EnhancerByCGLIB$$2a25c1b4$$FastClassByCGLIB$$2393400d extends FastClass {
public NewGirl$$EnhancerByCGLIB$$2a25c1b4$$FastClassByCGLIB$$2393400d(Class var1) {
super(var1);
}
public int getIndex(Signature var1) {
String var10000 = var1.toString();
switch(var10000.hashCode()) {
case -1882565338:
if (var10000.equals("CGLIB$equals$1(Ljava/lang/Object;)Z")) {
return 17;
}
break;
case -1870561232:
if (var10000.equals("CGLIB$findMethodProxy(Lorg/springframework/cglib/core/Signature;)Lorg/springframework/cglib/proxy/MethodProxy;")) {
return 14;
}
break;
case -1745842178:
if (var10000.equals("setCallbacks([Lorg/springframework/cglib/proxy/Callback;)V")) {
return 9;
}
break;
case -1641413109:
if (var10000.equals("newInstance([Lorg/springframework/cglib/proxy/Callback;)Ljava/lang/Object;")) {
return 4;
}
break;
case -1457535688:
if (var10000.equals("CGLIB$STATICHOOK1()V")) {
return 15;
}
break;
case -1411842725:
if (var10000.equals("CGLIB$hashCode$3()I")) {
return 19;
}
break;
case -1034266769:
if (var10000.equals("CGLIB$SET_STATIC_CALLBACKS([Lorg/springframework/cglib/proxy/Callback;)V")) {
return 10;
}
break;
case -1025895669:
if (var10000.equals("CGLIB$SET_THREAD_CALLBACKS([Lorg/springframework/cglib/proxy/Callback;)V")) {
return 11;
}
break;
case -988317324:
if (var10000.equals("newInstance([Ljava/lang/Class;[Ljava/lang/Object;[Lorg/springframework/cglib/proxy/Callback;)Ljava/lang/Object;")) {
return 5;
}
break;
case -508378822:
if (var10000.equals("clone()Ljava/lang/Object;")) {
return 3;
}
break;
case 610042816:
if (var10000.equals("newInstance(Lorg/springframework/cglib/proxy/Callback;)Ljava/lang/Object;")) {
return 6;
}
break;
case 1096387995:
if (var10000.equals("CGLIB$findLove$0()V")) {
return 16;
}
break;
case 1132856532:
if (var10000.equals("getCallbacks()[Lorg/springframework/cglib/proxy/Callback;")) {
return 13;
}
break;
case 1192015562:
if (var10000.equals("findLove()V")) {
return 7;
}
break;
case 1246779367:
if (var10000.equals("setCallback(ILorg/springframework/cglib/proxy/Callback;)V")) {
return 8;
}
break;
case 1306468936:
if (var10000.equals("CGLIB$toString$2()Ljava/lang/String;")) {
return 18;
}
break;
case 1364367423:
if (var10000.equals("getCallback(I)Lorg/springframework/cglib/proxy/Callback;")) {
return 12;
}
break;
case 1800494055:
if (var10000.equals("CGLIB$clone$4()Ljava/lang/Object;")) {
return 20;
}
break;
case 1826985398:
if (var10000.equals("equals(Ljava/lang/Object;)Z")) {
return 0;
}
break;
case 1913648695:
if (var10000.equals("toString()Ljava/lang/String;")) {
return 1;
}
break;
case 1984935277:
if (var10000.equals("hashCode()I")) {
return 2;
}
}
return -1;
}
public int getIndex(String var1, Class[] var2) {
switch(var1.hashCode()) {
case -1776922004:
if (var1.equals("toString")) {
switch(var2.length) {
case 0:
return 1;
}
}
break;
case -1295482945:
if (var1.equals("equals")) {
switch(var2.length) {
case 1:
if (var2[0].getName().equals("java.lang.Object")) {
return 0;
}
}
}
break;
case -1053468136:
if (var1.equals("getCallbacks")) {
switch(var2.length) {
case 0:
return 13;
}
}
break;
case -679433013:
if (var1.equals("findLove")) {
switch(var2.length) {
case 0:
return 7;
}
}
break;
case -331698278:
if (var1.equals("CGLIB$findLove$0")) {
switch(var2.length) {
case 0:
return 16;
}
}
break;
case -124978609:
if (var1.equals("CGLIB$equals$1")) {
switch(var2.length) {
case 1:
if (var2[0].getName().equals("java.lang.Object")) {
return 17;
}
}
}
break;
case -60403779:
if (var1.equals("CGLIB$SET_STATIC_CALLBACKS")) {
switch(var2.length) {
case 1:
if (var2[0].getName().equals("[Lorg.springframework.cglib.proxy.Callback;")) {
return 10;
}
}
}
break;
case -29025555:
if (var1.equals("CGLIB$hashCode$3")) {
switch(var2.length) {
case 0:
return 19;
}
}
break;
case 85179481:
if (var1.equals("CGLIB$SET_THREAD_CALLBACKS")) {
switch(var2.length) {
case 1:
if (var2[0].getName().equals("[Lorg.springframework.cglib.proxy.Callback;")) {
return 11;
}
}
}
break;
case 94756189:
if (var1.equals("clone")) {
switch(var2.length) {
case 0:
return 3;
}
}
break;
case 147696667:
if (var1.equals("hashCode")) {
switch(var2.length) {
case 0:
return 2;
}
}
break;
case 161998109:
if (var1.equals("CGLIB$STATICHOOK1")) {
switch(var2.length) {
case 0:
return 15;
}
}
break;
case 495524492:
if (var1.equals("setCallbacks")) {
switch(var2.length) {
case 1:
if (var2[0].getName().equals("[Lorg.springframework.cglib.proxy.Callback;")) {
return 9;
}
}
}
break;
case 1154623345:
if (var1.equals("CGLIB$findMethodProxy")) {
switch(var2.length) {
case 1:
if (var2[0].getName().equals("org.springframework.cglib.core.Signature")) {
return 14;
}
}
}
break;
case 1543336189:
if (var1.equals("CGLIB$toString$2")) {
switch(var2.length) {
case 0:
return 18;
}
}
break;
case 1811874389:
if (var1.equals("newInstance")) {
switch(var2.length) {
case 1:
String var10001 = var2[0].getName();
switch(var10001.hashCode()) {
case -1997738671:
if (var10001.equals("[Lorg.springframework.cglib.proxy.Callback;")) {
return 4;
}
break;
case 1364160985:
if (var10001.equals("org.springframework.cglib.proxy.Callback")) {
return 6;
}
}
case 2:
default:
break;
case 3:
if (var2[0].getName().equals("[Ljava.lang.Class;") && var2[1].getName().equals("[Ljava.lang.Object;") && var2[2].getName().equals("[Lorg.springframework.cglib.proxy.Callback;")) {
return 5;
}
}
}
break;
case 1817099975:
if (var1.equals("setCallback")) {
switch(var2.length) {
case 2:
if (var2[0].getName().equals("int") && var2[1].getName().equals("org.springframework.cglib.proxy.Callback")) {
return 8;
}
}
}
break;
case 1905679803:
if (var1.equals("getCallback")) {
switch(var2.length) {
case 1:
if (var2[0].getName().equals("int")) {
return 12;
}
}
}
break;
case 1951977610:
if (var1.equals("CGLIB$clone$4")) {
switch(var2.length) {
case 0:
return 20;
}
}
}
return -1;
}
public int getIndex(Class[] var1) {
switch(var1.length) {
case 0:
return 0;
default:
return -1;
}
}
public Object invoke(int var1, Object var2, Object[] var3) throws InvocationTargetException {
2a25c1b4 var10000 = (2a25c1b4)var2;
int var10001 = var1;
try {
switch(var10001) {
case 0:
return new Boolean(var10000.equals(var3[0]));
case 1:
return var10000.toString();
case 2:
return new Integer(var10000.hashCode());
case 3:
return var10000.clone();
case 4:
return var10000.newInstance((Callback[])var3[0]);
case 5:
return var10000.newInstance((Class[])var3[0], (Object[])var3[1], (Callback[])var3[2]);
case 6:
return var10000.newInstance((Callback)var3[0]);
case 7:
var10000.findLove();
return null;
case 8:
var10000.setCallback(((Number)var3[0]).intValue(), (Callback)var3[1]);
return null;
case 9:
var10000.setCallbacks((Callback[])var3[0]);
return null;
case 10:
2a25c1b4.CGLIB$SET_STATIC_CALLBACKS((Callback[])var3[0]);
return null;
case 11:
2a25c1b4.CGLIB$SET_THREAD_CALLBACKS((Callback[])var3[0]);
return null;
case 12:
return var10000.getCallback(((Number)var3[0]).intValue());
case 13:
return var10000.getCallbacks();
case 14:
return 2a25c1b4.CGLIB$findMethodProxy((Signature)var3[0]);
case 15:
2a25c1b4.CGLIB$STATICHOOK1();
return null;
case 16:
var10000.CGLIB$findLove$0();
return null;
case 17:
return new Boolean(var10000.CGLIB$equals$1(var3[0]));
case 18:
return var10000.CGLIB$toString$2();
case 19:
return new Integer(var10000.CGLIB$hashCode$3());
case 20:
return var10000.CGLIB$clone$4();
}
} catch (Throwable var4) {
throw new InvocationTargetException(var4);
}
throw new IllegalArgumentException("Cannot find matching method/constructor");
}
public Object newInstance(int var1, Object[] var2) throws InvocationTargetException {
2a25c1b4 var10000 = new 2a25c1b4;
2a25c1b4 var10001 = var10000;
int var10002 = var1;
try {
switch(var10002) {
case 0:
var10001.();
return var10000;
}
} catch (Throwable var3) {
throw new InvocationTargetException(var3);
}
throw new IllegalArgumentException("Cannot find matching method/constructor");
}
public int getMaxIndex() {
return 20;
}
}
- 3.NewGirl$$FastClassByCGLIB$$1cf5df8b.class
//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//
package com.zhunongyun.toalibaba.designpatterns.proxy.cglibproxy;
import java.lang.reflect.InvocationTargetException;
import org.springframework.cglib.core.Signature;
import org.springframework.cglib.reflect.FastClass;
public class NewGirl$$FastClassByCGLIB$$1cf5df8b extends FastClass {
public NewGirl$$FastClassByCGLIB$$1cf5df8b(Class var1) {
super(var1);
}
public int getIndex(Signature var1) {
String var10000 = var1.toString();
switch(var10000.hashCode()) {
case 1192015562:
if (var10000.equals("findLove()V")) {
return 0;
}
break;
case 1826985398:
if (var10000.equals("equals(Ljava/lang/Object;)Z")) {
return 1;
}
break;
case 1913648695:
if (var10000.equals("toString()Ljava/lang/String;")) {
return 2;
}
break;
case 1984935277:
if (var10000.equals("hashCode()I")) {
return 3;
}
}
return -1;
}
public int getIndex(String var1, Class[] var2) {
switch(var1.hashCode()) {
case -1776922004:
if (var1.equals("toString")) {
switch(var2.length) {
case 0:
return 2;
}
}
break;
case -1295482945:
if (var1.equals("equals")) {
switch(var2.length) {
case 1:
if (var2[0].getName().equals("java.lang.Object")) {
return 1;
}
}
}
break;
case -679433013:
if (var1.equals("findLove")) {
switch(var2.length) {
case 0:
return 0;
}
}
break;
case 147696667:
if (var1.equals("hashCode")) {
switch(var2.length) {
case 0:
return 3;
}
}
}
return -1;
}
public int getIndex(Class[] var1) {
switch(var1.length) {
case 0:
return 0;
default:
return -1;
}
}
public Object invoke(int var1, Object var2, Object[] var3) throws InvocationTargetException {
NewGirl var10000 = (NewGirl)var2;
int var10001 = var1;
try {
switch(var10001) {
case 0:
var10000.findLove();
return null;
case 1:
return new Boolean(var10000.equals(var3[0]));
case 2:
return var10000.toString();
case 3:
return new Integer(var10000.hashCode());
}
} catch (Throwable var4) {
throw new InvocationTargetException(var4);
}
throw new IllegalArgumentException("Cannot find matching method/constructor");
}
public Object newInstance(int var1, Object[] var2) throws InvocationTargetException {
NewGirl var10000 = new NewGirl;
NewGirl var10001 = var10000;
int var10002 = var1;
try {
switch(var10002) {
case 0:
var10001.();
return var10000;
}
} catch (Throwable var3) {
throw new InvocationTargetException(var3);
}
throw new IllegalArgumentException("Cannot find matching method/constructor");
}
public int getMaxIndex() {
return 3;
}
}
重写了 NewGirl 类的所有方法,我们通过代理类的源码可以看到,代理类会获得所有在父类继承来的方法,并且会有 MethodProxy 与之对应,比如 MethodCGLIB0findLoveProxy;这些方法在代理类的 findLove()中都有调用
//代理方法(methodProxy.invokeSuper 会调用)
final void CGLIB$findLove$0()
{
super.findLove();
}
//被代理方法(methodProxy.invoke 会调用,这就是为什么在拦截器中调用 methodProxy.invoke 会死循环,一直在调 用拦截器)
public final void findLove()
{
CGLIB$CALLBACK_0;
if(CGLIB$CALLBACK_0 != null) goto _L2; else goto _L1
_L1:
JVM INSTR pop;
CGLIB$BIND_CALLBACKS(this);
CGLIB$CALLBACK_0;
_L2:
JVM INSTR dup ;
JVM INSTR ifnull 37;
goto _L3 _L4
_L3:
break MISSING_BLOCK_LABEL_21;
_L4:
break MISSING_BLOCK_LABEL_37;
this;
CGLIB$findLove$0$Method;
CGLIB$emptyArgs;
CGLIB$findLove$0$Proxy;
//调用拦截器
intercept();
return;
super.findLove();
return;
}
调用过程:
代理对象调用 this.findLove()方法->调用拦截器->methodProxy.invokeSuper->CGLIB$findLove$0->被代理对象 findLove()方法
此时,我们发现拦截器 MethodInterceptor 中就是由 MethodProxy 的 invokeSuper 方法调用代理方法的,MethodProxy 非常关键,我们分析一下它具体做了什么
public class MethodProxy {
private Signature sig1;
private Signature sig2;
private MethodProxy.CreateInfo createInfo;
private final Object initLock = new Object();
private volatile MethodProxy.FastClassInfo fastClassInfo;
public static MethodProxy create(Class c1, Class c2, String desc, String name1, String name2) {
MethodProxy proxy = new MethodProxy();
proxy.sig1 = new Signature(name1, desc);
proxy.sig2 = new Signature(name2, desc);
proxy.createInfo = new MethodProxy.CreateInfo(c1, c2);
return proxy;
}
...
private static class CreateInfo {
Class c1;
Class c2;
NamingPolicy namingPolicy;
GeneratorStrategy strategy;
boolean attemptLoad;
public CreateInfo(Class c1, Class c2) {
this.c1 = c1;
this.c2 = c2;
AbstractClassGenerator fromEnhancer = AbstractClassGenerator.getCurrent();
if (fromEnhancer != null) {
this.namingPolicy = fromEnhancer.getNamingPolicy();
this.strategy = fromEnhancer.getStrategy();
this.attemptLoad = fromEnhancer.getAttemptLoad();
}
}
}
...
}
继续看 invokeSuper()方法
public Object invokeSuper(Object obj, Object[] args) throws Throwable {
try {
this.init();
MethodProxy.FastClassInfo fci = this.fastClassInfo;
return fci.f2.invoke(fci.i2, obj, args);
} catch (InvocationTargetException var4) {
throw var4.getTargetException();
}
}
...
private static class FastClassInfo {
FastClass f1;
FastClass f2;
int i1;
int i2;
private FastClassInfo() {
}
}
上面代码调用过程就是获取到代理类对应的 FastClass,并执行了代理方法.还记得之前生成三个 class 文件吗?
- Customer3feeb52a6aad62f1.class 就是代理类的 FastClass
- Customer2669574a.class 就是被代理类的 FastClass
CGLib 动态代理执行代理方法效率之所以比 JDK 的高是因为 Cglib 采用了 FastClass 机制,它的原理简单来说就是:
为代理类和被代理类各生成一个 Class,这个 Class 会为代理类或被代理类的方法分配一个 index(int 类型).这个 index 当做一个入参,FastClass 就可以直接定位要调用的方法直接进行调用,这样省去了反射调用,所以调用效率比 JDK 动态代理通过反射调用高
6. 总结
6.1 CGlib 动态代理和 JDK 动态代理对比
两种动态代理都是通过生成新的类,去实现增强被代理类代码逻辑的功能
- JDK 动态代理采用实现被代理对象接口
- CGlib 动态代理采用继承被代理对象,并覆盖父类方法
- JDK 动态代理对于用户而言,必须要有一个接口实现,目标类相对来说复杂
- CGlib 动态代理可以代理任意一个普通的对象,没有任何要求
- JDK 动态代理生成代理的逻辑简单,执行效率相对较低,每次都要反射动态调用
- CGlib 生成代理逻辑更加复杂,调用效率更高,生成一个包含了所有的逻辑的 FastClass,不再需要反射调用
- CGlib 代理有坑,不能代理 final 方法
6.2 代理模式优点
- 代理模式能将代理对象与真实被调用的目标对象分离
- 一定程度上降低了系统耦合程度,易于扩展
- 代理模式起到了保护目标对象的作用
- 增强目标对象的职责
6.2 代理模式缺点
- 代理模式会造成系统设计中类的数量增加
- 在客户端和目标对象之间增加了一个代理对象,会造成请求处理速度变慢
- 增加了系统的复杂度
7. Spring 与动态代理
7.1 动态代理在 Spring 源码中的应用
先看 ProxyFactoryBean 核心的方法就是 getObject()方法,我们来看一下源码
public Object getObject() throws BeansException {
initializeAdvisorChain();
if (isSingleton()) {
return getSingletonInstance();
} else {
if (this.targetName == null) {
logger.warn("Using non-singleton proxies with singleton targets is often undesirable. "
+ "Enable prototype proxies by setting the 'targetName' property.");
}
return newPrototypeInstance();
}
}
在 getObject()方法中,主要调用 getSingletonInstance()和 newPrototypeInstance()
在 Spring 的配置中,如果不做任何设置,那么 Spring 代理生成的 Bean 都是单例对象.如果修改 scope 则每次创建一个新的原型对象.newPrototypeInstance()里面的逻辑比较复杂,我们后面的课程再做深入研究,这里我们先做简单的了解
Spring 利用动态代理实现 AOP 有两个非常重要的,一个是 JdkDynamicAopProxy 类和 CglibAopProxy 类,来看一下类图
7.2 Spring 中代理模式的选择
- 当 Bean 有实现接口时,Spring 就会用 JDK 的动态代理
- 当 Bean 没有实现接口时,Spring 会选择 CGlib
- Spring 可以通过配置强制使用 CGlib,只需在 Spring 的配置文件中加入如下代码
参考资料:
https://docs.spring.io/spring/docs/current/spring-framework-reference/core.html