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;
}
}
