//定义接口
public interface Foo{ void doAction();}//实现一public class FooImpl implements Foo{ public FooImpl() { }public void doAction()
{ System.out.println("in FooImp1.doAction()"); }}//实现二public class FooImpl2 implements Foo{ public FooImpl2() { } public void doAction() { System.out.println("in FooImp2.doAction()"); }}
//代理类public class DynamicSubject implements InvocationHandler{ private Object sub;public DynamicSubject()
{ }public DynamicSubject(Object obj)
{ sub = obj; }public Object invoke(Object proxy, Method method, Object[] args) throws Throwable
{ System.out.println("before calling " + method);method.invoke(sub, args);
System.out.println("after calling " + method);
return null;
}}
//测试public class Demo{ public static void main(String[] args){// 1.通用的动态代理实现
CommonInvocationHandler handler = new CommonInvocationHandler();
Foo f;
// 2.接口实现1
handler.setTarget(new FooImpl());
f = (Foo) Proxy.newProxyInstance(Foo.class.getClassLoader(),
new Class[] { Foo.class },
handler);
f.doAction();
// 3.接口实现2
handler.setTarget(new FooImpl2());
f = (Foo) Proxy.newProxyInstance(Foo.class.getClassLoader(),
new Class[] { Foo.class },
handler);
f.doAction();
}}----------->>也就是面向接口编程，完全可以写一个工厂类实现的，为什么要采用这个方式，如：class Factory{
Foo fo ; public Factory(Foo fo){ this.fo = fo;}public Foo getInstence(){ return fo;}}然后创建Factory对象=============》》 有什么差别么？？
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Proxy;public class AopTest { public static void main(String[] args) { Before before = new Before() { public void before() { System.out.println("...before..."); } }; After after = new After() { public void after() { System.out.println("...after..."); } }; Hello hello = null; // 普通方法执行 System.out.println("-------------普通执行-------------"); hello = new HelloEnglish(); hello.sayHello("bao110908"); hello.sayHi("bao110908"); System.out.println(); // 切入方法执行前（前置增强） System.out.println("-------------前置增强-------------"); hello = HelloAopManager.getHelloProxy(new HelloEnglish(), before); hello.sayHello("bao110908"); hello.sayHi("bao110908"); // sayHi 方法没有标注 @Enhancement 所以不会进行代码切入 System.out.println(); // 切入方法执行后（后置增强） System.out.println("-------------后置增强-------------"); hello = HelloAopManager.getHelloProxy(new HelloEnglish(), after); hello.sayHello("bao110908"); hello.sayHi("bao110908"); System.out.println(); // 切入方法执行前和执行后（环绕增强） System.out.println("-------------环绕增强-------------"); hello = HelloAopManager.getHelloProxy(new HelloEnglish(), before, after); hello.sayHello("bao110908"); hello.sayHi("bao110908"); System.out.println(); }}@Retention(RetentionPolicy.RUNTIME)@interface Enhancement { }interface Hello { @Enhancement public void sayHello(String name); public void sayHi(String name);}class HelloChinese implements Hello { public void sayHello(String name) { System.out.println(name + "，您好"); } public void sayHi(String name) { System.out.println("哈啰，" + name); }}class HelloEnglish implements Hello { public void sayHello(String name) { System.out.println("Hello, " + name); } public void sayHi(String name) { System.out.println("hi, " + name); }}class HelloAopManager { private HelloAopManager(){ } public static Hello getHelloProxy(Hello hello, Before before) { return getHelloProxy(hello, before, null); } public static Hello getHelloProxy(Hello hello, After after) { return getHelloProxy(hello, null, after); } public static Hello getHelloProxy(Hello hello, Before before, After after) { HelloHandler handler = new HelloHandler(); if(before != null) { handler.setBefore(before); } if(after != null) { handler.setAfter(after); } return handler.bind(hello); } }/** * 前置增强接口 */interface Before { public void before();}/** * 后置增强接口 */interface After { public void after();}class HelloHandler implements InvocationHandler { /** * 需要进行代理的实例 */ private Hello hello = null; /** * 前置增强 */ private Before before = null; /** * 后置增强 */ private After after = null; /** * InvocationHandler 接口的实现方法，进行动态代理 */ public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { // 看看接口中方法是否标注了需要 Enhancement boolean b = method.isAnnotationPresent(Enhancement.class); if(!b){ // 没有标注的话，按原方法执行 return method.invoke(hello, args); } // 有标注的话，进行方法的前置和后置增强 if(before != null) { before.before(); } Object obj = method.invoke(hello, args); if(after != null) { after.after(); } return obj; } /** * 将传入的 Hello 与 InvocationHandler 进行绑定，以获得代理类的实例 * @param hello * @return */ public Hello bind(Hello hello) { this.hello = hello; Hello helloProxy = (Hello)Proxy.newProxyInstance( hello.getClass().getClassLoader(), hello.getClass().getInterfaces(), this ); return helloProxy; } public void setAfter(After after) { this.after = after; } public void setBefore(Before before) { this.before = before; }}