asm

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cglib代理指定只代理某个方法

cglib代理指定只代理某个方法importnet.sf.cglib.proxy.*;importjava.lang.reflect.Method;classSampleClass{publicvoidtest(){System.out.println("test");}publicvoidtest2(){System.out.println("test2");}}publicclasstest{publicstaticvoidmain(String[]args){Enhancerenhancer=newEnhancer();enhancer.setSuperclass(SampleClass.class);CallbackHelpercallbackHelper=newCallbackHelper(SampleClass.class,newClass[0]){@OverrideprotectedObjectgetCallback(Methodmethod){//只代理方法名是test的方法if(method.getName().equals("test")){returnnewMethodInterceptor(){@OverridepublicObjectintercept(Objecto,Methodmethod,Object[]objects,MethodProxymethodProxy)throwsThrowable{System.out.print("代理---");returnmethodProxy.invokeSuper(o,objects);}};}else{returnNoOp.INSTANCE;}}};enhancer.setCallbackFilter(callbackHelper);enhancer.setCallbacks(callbackHelper.getCallbacks());SampleClassproxy=(SampleClass)enhancer.create();proxy.test();proxy.test2();}}输出：代理---testtest2

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cglib代理常用接口和api

一、MethodInterceptor二、InvocationHandler三、FixedValue四、ImmutableBean五、BeanGenerator六、BeanMap 关于cglib代理的概念和原理，这里就不多说了，详细请参考以往的博客：初步探究cglib动态代理的原理：http://www.jiajiajia.club/blog/artical/yjw520/134cglib动态代理底层实现分析java：http://www.jiajiajia.club/official/weblog/yjw520/34 本篇主要介绍cglib的主要（常用）的api。一、MethodInterceptor入门的hellowordimportnet.sf.cglib.proxy.*;importjava.lang.reflect.Method;classSampleClass{publicvoidtest(){System.out.println("test");}publicvoidtest2(){System.out.println("test2");}}publicclasstest{publicstaticvoidmain(String[]args){Enhancerenhancer=newEnhancer();enhancer.setSuperclass(SampleClass.class);enhancer.setCallback(newMethodInterceptor(){@OverridepublicObjectintercept(Objecto,Methodmethod,Object[]objects,MethodProxymethodProxy)throwsThrowable{System.out.println("before");Objectres=methodProxy.invokeSuper(o,objects);System.out.println("after");returnres;}});SampleClassproxy=(SampleClass)enhancer.create();proxy.test();proxy.test2();}}输出：beforetestafterbeforetest2after 该种方法将代理SampleClass类的非final的所有成员方法。如果只想代理某个指定的方法，可以实现CallbackFilter接口，如下：importnet.sf.cglib.proxy.*;importjava.lang.reflect.Method;classSampleClass{publicvoidtest(){System.out.println("test");}publicvoidtest2(){System.out.println("test2");}}publicclasstest{publicstaticvoidmain(String[]args){Enhancerenhancer=newEnhancer();enhancer.setSuperclass(SampleClass.class);CallbackHelpercallbackHelper=newCallbackHelper(SampleClass.class,newClass[0]){@OverrideprotectedObjectgetCallback(Methodmethod){//只代理方法名是test的方法if(method.getName().equals("test")){returnnewMethodInterceptor(){@OverridepublicObjectintercept(Objecto,Methodmethod,Object[]objects,MethodProxymethodProxy)throwsThrowable{System.out.print("代理---");returnmethodProxy.invokeSuper(o,objects);}};}else{returnNoOp.INSTANCE;}}};enhancer.setCallbackFilter(callbackHelper);enhancer.setCallbacks(callbackHelper.getCallbacks());SampleClassproxy=(SampleClass)enhancer.create();proxy.test();proxy.test2();}}输出：代理---testtest2 这种方法可以指定具体代理某一个方法。二、InvocationHandler InvocationHandler可以实现对接口的代理，类似与mybatis，代码中开发者只需要写一个接口和一个xml，mybatis会根据xml的描述信息，帮你生成对应的方法实现，参数的解析、sql的生成、发送、结果集的封装等都不用开发者去写。而其中的原理就是利用了代理模式。首先定义一个接口，这个接口里有各种返回值类型的方法。importjava.util.List;publicinterfaceTestInterface{StringtestString(Integerid);inttestInt(Stringvalue);ListtestList(Integerage,Integerg);SampleClasstestSampleClass();} 用代理模式去实现这些方法。实现类交由cglib去动态创建。importnet.sf.cglib.proxy.*;importjava.lang.reflect.Method;importjava.util.ArrayList;importjava.util.List;publicclasstest2{publicstaticvoidmain(String[]args){Class[]classes={TestInterface.class};Enhancerenhancer=newEnhancer();enhancer.setInterfaces(classes);CallbackHelpercallbackHelper=newCallbackHelper(Object.class,classes){@OverrideprotectedObjectgetCallback(Methodmethod){//只代理TestInterface中的方法if(method.getDeclaringClass()==TestInterface.class){returnnewInvocationHandler(){@OverridepublicObjectinvoke(Objecto,Methodmethod,Object[]objects)throwsThrowable{System.out.print("参数：");for(Objectobject:objects){System.out.print(object+"\t");}System.out.println();Class?returnType=method.getReturnType();if(returnType==int.class||returnType==Integer.class){//返回值类型是整数类型return1;}elseif(returnType==String.class){//返回值类型是字符串return"string";}elseif(returnType==List.class){//返回值类型是集合ArrayListarrayList=newArrayList();arrayList.add("11");returnarrayList;}//...等等else{//自定义类型returnreturnType.newInstance();}}};}else{//什么都不做returnNoOp.INSTANCE;}}};enhancer.setCallbackFilter(callbackHelper);enhancer.setCallbacks(callbackHelper.getCallbacks());TestInterfaceproxy=(TestInterface)enhancer.create();System.out.println("返回值："+proxy.testInt("123"));;System.out.println("返回值："+proxy.testList(1,1));;System.out.println("返回值："+proxy.testString(1));;System.out.println("返回值："+proxy.testSampleClass());;}}三、FixedValue 该方法会对所有拦截的方法返回同样的值。importnet.sf.cglib.proxy.*;importjava.lang.reflect.Method;classSampleClass{publicStringtest(){return"test";}publicStringtest2(){return"test2";}}publicclasstest{publicstaticvoidmain(String[]args){Enhancerenhancer=newEnhancer();enhancer.setSuperclass(SampleClass.class);CallbackHelpercallbackHelper=newCallbackHelper(SampleClass.class,newClass[0]){@OverrideprotectedObjectgetCallback(Methodmethod){//只代理返回值类型是String类型的方法，如果返回值类型不是String将会抛异常。if(method.getReturnType()==String.class){returnnewFixedValue(){@OverridepublicObjectloadObject()throwsException{return"proxy...";}};}else{returnNoOp.INSTANCE;}}};enhancer.setCallbackFilter(callbackHelper);enhancer.setCallbacks(callbackHelper.getCallbacks());SampleClassproxy=(SampleClass)enhancer.create();System.out.println(proxy.test());System.out.println(proxy.test2());System.out.println(proxy.toString());System.out.println(proxy.hashCode());}}输出：proxy...proxy...proxy...1874154700返回值是String类型的都返回同样的值。四、ImmutableBean 不可变的Bean。ImmutableBean允许创建一个原来对象的包装类，这个包装类是不可变的，任何改变底层对象的包装类操作都会抛出IllegalStateException。但是我们可以通过直接操作底层对象来改变包装类对象。importnet.sf.cglib.beans.ImmutableBean;classSampleBean{SampleBean(){}SampleBean(intid){this.id=id;}privateintid;publicintgetId(){returnthis.id;}publicvoidsetId(intid){this.id=id;}}publicclasstest2{publicstaticvoidmain(String[]args){SampleBeanbean=newSampleBean();bean.setId(1);SampleBeanimmutableBean=(SampleBean)ImmutableBean.create(bean);System.out.println(bean.getId());System.out.println(immutableBean.getId());bean.setId(2);System.out.println(bean.getId());System.out.println(immutableBean.getId());immutableBean.setId(3);//包装类修改将会抛异常System.out.println(bean.getId());System.out.println(immutableBean.getId());}}输出：1122Exceptioninthread"main"java.lang.IllegalStateException:Beanisimmutableatcom.example.SampleBean$$ImmutableBeanByCGLIB$$e23e512b.setId(generated)atcom.example.test2.main(test2.java:31)五、BeanGenerator cglib提供的一个操作bean的工具，使用它能够在运行时动态的创建一个bean。importjava.lang.reflect.InvocationTargetException;importjava.lang.reflect.Method;publicclasstest2{publicstaticvoidmain(String[]args)throwsNoSuchMethodException,InvocationTargetException,IllegalAccessException{BeanGeneratorbeanGenerator=newBeanGenerator();beanGenerator.addProperty("id",int.class);ObjectmyBean=beanGenerator.create();Methodsetter=myBean.getClass().getMethod("setId",int.class);setter.invoke(myBean,1);Methodgetter=myBean.getClass().getMethod("getId");System.out.println(getter.invoke(myBean));}}动态创建一个类，该类包含一个int类型的id属性，并包含get,set方法。六、BeanMap BeanMap类实现了JavaMap，将一个bean对象中的所有属性转换为一个String-to-Obejct的JavaMapimportnet.sf.cglib.beans.BeanMap;importjava.lang.reflect.InvocationTargetException;classBean{intid=1;Stringname="name";publicintgetId(){returnthis.id;}publicStringgetName(){returnthis.name;}}publicclasstest2{publicstaticvoidmain(String[]args)throwsNoSuchMethodException,InvocationTargetException,IllegalAccessException{Beanbean=newBean();BeanMapbeanMap=BeanMap.create(bean);Objectid=beanMap.get("id");Objectname=beanMap.get("name");System.out.println(id);System.out.println(name);}}输出：1name

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