aop代理示例

java  code

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; } }