代理模式第二篇

通过代理模式第一篇，我们已经有了RMI的基础知识，现在可以用RMI实现糖果机的远程代理了。远程服务是一个GumballMachine糖果机，具有一些属性和获得属性值得方法。客户端是GumballMonitor监视器，监视器和远程服务糖果机不在同一个JVM堆中。

实现代码如下：

服务端：

远程服务接口，客户端所需要调用的方法都应该在接口中声明：

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

远程服务类：

public class GumballMachine extends UnicastRemoteObject implements GumballMachineRemote{
    int count;
    String location;
    State state;

protected GumballMachine(String location,int numberGumballs) throws RemoteException {
    super();
    // TODO Auto-generated constructor stub
    this.location=location;
    this.count=numberGumballs;
}

@Override
public String getLocation() {
    // TODO Auto-generated method stub
    return location;
}

@Override
public int getCount() {
    // TODO Auto-generated method stub
    return count;
}

@Override
public State getState() {
    // TODO Auto-generated method stub
    return state;
}

public void setCount(int count) {
    this.count = count;
}

public void setLocation(String location) {
    this.location = location;
}

public void setState(State state) {
    this.state = state;
}

　　

状态接口：
}

public interface State extends Serializable{
    public void insertQuarter();
    public void ejectQuarter();
    public void turnCrank();
    public void dispense();
}

public class NoQuarterState implements State{

@Override
public void insertQuarter() {
    // TODO Auto-generated method stub

}

@Override
public void ejectQuarter() {
    // TODO Auto-generated method stub

}

@Override
public void turnCrank() {
    // TODO Auto-generated method stub

}

@Override
public void dispense() {
    // TODO Auto-generated method stub

}

}

　　

远程服务端测试类：

public class GumballMachineTestDriver {
    public static void main(String [] args)
    {
    GumballMachine gumballMachine=null;
    int count;
    if(args.length<2)
    {
    System.out.println("GumballMachine <name> <inventory>");
    System.exit(1);
    }
    count=Integer.parseInt(args[1]);
    try {
    gumballMachine=new GumballMachine(args[0],count);
    Naming.rebind("//" + args[0] + "/gumballmachine", gumballMachine);
    } catch (Exception e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}
}
}

　　

客户端：

监视器类：

public class GumballMonitor {
    GumballMachineRemote machine;

    public GumballMonitor(GumballMachineRemote machine)
    {
    this.machine=machine;
    }

    public void report()
    {
    try
    {
    System.out.println("Gumball Machine: "+ machine.getLocation());
    System.out.println("Current inventory: "+ machine.getCount() + " gumballs");
    System.out.println("Current state: " + machine.getState());
    }catch(RemoteException e)
    {
    e.printStackTrace();
    }
}

　　

监视器测试类：

public class GumballMonitorTestDriver {
    public static void main(String [] args)
    {
    String location[]={
    "rmi://127.0.0.1/gumballmachine",
    "rmi://127.0.0.1/gumballmachine",
    "rmi://127.0.0.1/gumballmachine"
    };
    GumballMonitor[] monitor=new GumballMonitor[location.length];
    for(int i=0;i<location.length;i++)
    {
        try
        {
        GumballMachineRemote machine=    (GumballMachineRemote)Naming.lookup(location[i]);
        monitor[i]=new GumballMonitor(machine);
        }catch(Exception e)
            {
                e.printStackTrace();
            }
    }

    for(int i=0;i<location.length;i++)
    {
        monitor[i].report();
    }
    }
}