動態代理及工廠的簡單實現

1.定義用到的接口

public interface Bussiness {
     void doBussiness();
}

public interface Log {
     void before();
     void after();
}

2.定義接口的實現類

public class BussinessImpl implements Bussiness {

 @Override
 public void doBussiness() {
  System.out.println("業務邏輯部分");
 }
 
}

 

public class LogImpl implements Log{

 @Override
 public void before() {
  System.out.println("方法執行以前");
  
 }

 @Override
 public void after() {
  System.out.println("方法執行以後");
  
 }

}

3.這是實現代理最關鍵的類Handler  須要實現InvocationHandler  重寫invoke()方法

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

public class Handler implements InvocationHandler {
 
 private Bussiness target = null;
 private Log log = null;
 
 public void setTarget(Bussiness target){
  this.target =   target;
 }
 
 public void setLog(Log log){
  this.log = log;
 }
 
 @Override
 public Object invoke(Object proxy, Method method, Object[] args)
   throws Throwable {
  log.before();
  Object result = method.invoke(target,args);
  log.after();
  return result;
 }
 
 public Object getProxy(){
  Bussiness buss = (Bussiness)Proxy.newProxyInstance(target.getClass().getClassLoader() ,
    target.getClass().getInterfaces(),this);
  return buss;
 }
 
}

4.工廠類的簡單實現

public class Factory {

 /**
  * @param args
  */
 public static void main(String[] args) {
  BussinessImpl impl = new BussinessImpl();
  LogImpl logImpl = new LogImpl();
  
  Handler handler = new Handler();
  handler.setLog(logImpl);
  handler.setTarget(impl);
  
  Bussiness buss = (Bussiness) handler.getProxy();
  buss.doBussiness();

 }

}

 

Bussiness buss = (Bussiness) handler.getProxy();
buss.doBussiness();

當調用代理類的方法時 會調用Handler的invoke()方法。

 @Override public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { log.before(); Object result = method.invoke(target,args); log.after(); return result; }