JDK动态代理

jdk的动态代理主要涉及的到java.lang.reflect包中的: Proxy 和 InvocationHandler 这两个类

PerformanceMonitor:

package com.baobaotao.service.proxy;

public class PerformanceMonitor {
 private static ThreadLocal<MethodPerformance> performanceRecord = new ThreadLocal<MethodPerformance>();
 
 public static void begin(String method) {
  System.out.println("begin monitor...");
  MethodPerformance mp = new MethodPerformance(method);
  performanceRecord.set(mp);
 }
 
 public static void end() {
  System.out.println("end monitor...");
  MethodPerformance mp = performanceRecord.get();
  mp.printPerformance();
 }
}

MethodPerformance:

package com.baobaotao.service.proxy;

public class MethodPerformance {
 private long begin;
 private long end;
 private String serviceMethod;
 
 public MethodPerformance(String serviceMethod) {
  this.serviceMethod = serviceMethod;
  this.begin = System.currentTimeMillis();
 }
 
 public void printPerformance() {
  end = System.currentTimeMillis();
  long elapse = end - begin;
  System.out.println(serviceMethod + "花费" + elapse + "毫秒");
 }
}
PerformanceHandler

package com.baobaotao.service.proxy;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;

public class PerformanceHandler implements InvocationHandler{
 private Object target;
 public PerformanceHandler(Object target) {
  this.target = target;
 }
 
 public Object invoke(Object proxy, Method method, Object[] args)
   throws Throwable {
  //PerformanceMonitor是自己定义的一个监听类
  PerformanceMonitor.begin(target.getClass().getName() + "." + method.getName());
  Object obj = method.invoke(target, args);
  PerformanceMonitor.end();
  return obj;
 }
}

TestForumService:

package com.baobaotao.service.proxy;

import java.lang.reflect.Proxy;

import com.baobaotao.service.proxy.impl.ForumServiceImpl;

public class TestForumService {
 
 public static void main(String[] args) {
  //希望被代理的目标业务类
  ForumService target = new ForumServiceImpl();
  //将目标类与横切代码编织到一起
  PerformanceHandler handler = new PerformanceHandler(target);
  //根据编织了目标业务类逻辑和性能监视横切逻辑的InvotationHandler实例创建代理实例
  ForumService proxy = (ForumService)Proxy.newProxyInstance(target.getClass().getClassLoader(), target.getClass().getInterfaces(), handler); 
  proxy.insert();
 }
}