JAVA设计模式学习笔记-代理模式

远程糖果机监控项目

监控糖果机：地点、糖果库存和当前状态
本地糖果机监控怎么做

package com.java.jikexueyuan.agentmode.candymachine;

import java.rmi.RemoteException;
import java.rmi.server.UnicastRemoteObject;

import com.java.jikexueyuan.agentmode.candymachinermi.CandyMachineRemote;

public class CandyMachine extends UnicastRemoteObject implements CandyMachineRemote{

	State mSoldOutState;
	State mOnReadyState;
	State mHasCoin;
	State mSoldState;
	State mWinnerState;
	private String location="";
	private State state;
	private int count = 0;

	public CandyMachine(String location,int count) throws RemoteException{
		this.location=location;
		this.count = count;
		mSoldOutState = new SoldOutState(this);
		mOnReadyState = new OnReadyState(this);
		mHasCoin = new HasCoin(this);
		mSoldState = new SoldState(this);
		mWinnerState = new WinnerState(this);
		if (count > 0) {
			state = mOnReadyState;
		} else {
			state = mSoldOutState;
		}
	}
	public String getLocation()
	{
		return location;
	}
	public void setState(State state) {
		this.state = state;
	}

	public void insertCoin() {
		state.insertCoin();
	}

	public void returnCoin() {
		state.returnCoin();
	}

	public void turnCrank() {
		state.turnCrank();
		state.dispense();
	}

	void releaseCandy() {

		// TODO Auto-generated method stub
		if (count > 0) {
			count = count - 1;
			System.out.println("a candy rolling out!");
		}

	}

	public int getCount() {
		return count;
	}

	public void printstate() {
		state.printstate();
	}
	public State getstate() {
		return state;
	}
}

package com.java.jikexueyuan.agentmode;

import java.util.ArrayList;

import com.java.jikexueyuan.agentmode.candymachine.CandyMachine;

public class Monitor {
	private ArrayList<CandyMachine> candyMachinelst;

	public Monitor() {
		candyMachinelst = new ArrayList<CandyMachine>();
	}

	public void addMachine(CandyMachine mCandyMachine) {
		candyMachinelst.add(mCandyMachine);
	}

	public void report() {
		CandyMachine mCandyMachine;
		for (int i = 0, len = candyMachinelst.size(); i < len; i++) {
			mCandyMachine = candyMachinelst.get(i);
			System.out.println("Machine Loc:" + mCandyMachine.getLocation());
			System.out.println("Machine Candy count:"
					+ mCandyMachine.getCount());
			System.out.println("Machine State:"
					+ mCandyMachine.getstate().getstatename());

		}

	}

}

package com.java.jikexueyuan.agentmode;

import java.rmi.RemoteException;

import com.java.jikexueyuan.agentmode.candymachine.CandyMachine;

public class MainTest {
	public static void main(String[] args) throws RemoteException {
		Monitor mMonitor=new Monitor();
		CandyMachine mCandyMachine = new CandyMachine("NY",6);
		mMonitor.addMachine(mCandyMachine);
		
		mCandyMachine = new CandyMachine("TK",4);
		mCandyMachine.insertCoin();
		mMonitor.addMachine(mCandyMachine);
		
		mCandyMachine = new CandyMachine("Bj",14);
		mCandyMachine.insertCoin();	
		mCandyMachine.turnCrank();
		mMonitor.addMachine(mCandyMachine);

		mMonitor.report();
	}
}

远程代理：远程对象的本地代表，通过它可以让远程对象当本地对象来调用。
远程代理通过网络和真正的远程对象沟通信息。

利用Java RMI实现远程代理

代理模式：为一个对象提供一个替身，以控制对这个对象的访问
被代理的对象可以是远程对象、创建开销大的对象或需要安全控制的对象
代理模式有很多变体，都是为了控制与管理对象访问

RMI远程方法调用是计算机之间通过网络实现对象调用的一种通讯机制。
使用这种机制，一台计算机上的对象可以调用另外一台计算机上的对象来获取远
程数据。
在过去，TCP/IP通讯是远程通讯的主要手段，面向过程的开发。
而RPC使程序员更容易地调用远程程序，但在面对复杂的信息传讯时，RPC依然
未能很好的支持
RMI被设计成一种面向对象开发方式，允许程序员使用远程对象来实现通信

制作远程接口：接口文件
远程接口的实现：Service文件
RMI服务端注册，开启服务
RMI代理端通过RMI查询到服务端，建立联系，通过接口调用远程方法

接口

package com.java.jikexueyuan.agentmode.rmi;

import java.rmi.Remote;
import java.rmi.RemoteException;

public interface MyRemote extends Remote{

	public String sayHello() throws RemoteException;
	
}

package com.java.jikexueyuan.agentmode.rmi;

import java.net.MalformedURLException;
import java.rmi.Naming;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.server.UnicastRemoteObject;

@SuppressWarnings("serial")
public class MyRemoteImpl extends UnicastRemoteObject implements MyRemote{

	protected MyRemoteImpl() throws RemoteException {
		super();
		// TODO Auto-generated constructor stub
	}

	@Override
	public String sayHello() throws RemoteException {
		// TODO Auto-generated method stub
		return "Hello World!";
	}
	public static void main(String[] args) {
		
		try {
			MyRemote service=new MyRemoteImpl();
			// LocateRegistry.createRegistry(6600);  
			Naming.rebind("rmi://127.0.0.1:6600/RemoteHello", service);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			System.out.println( e.toString());
		} 
		
		
	}
}

package com.java.jikexueyuan.agentmode.rmi;

import java.rmi.Naming;

public class MyRemoteClient {
	public static void main(String[] args) {
		
		new MyRemoteClient().go();
	}
	
	public void go()
	{
		try {
			MyRemote service=(MyRemote)Naming.lookup("rmi://127.0.0.1:6600/RemoteHello");
			String s=service.sayHello();
			System.out.println(s);

		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} 
	}
}

示例项目类结构图

package com.java.jikexueyuan.agentmode.candymachinermi;

import java.rmi.Remote;
import java.rmi.RemoteException;

import com.java.jikexueyuan.agentmode.candymachine.State;

public interface CandyMachineRemote extends Remote{
	public String  getLocation() throws RemoteException;
	public int getCount() throws RemoteException;
	public State getstate() throws RemoteException;
}