Java RMI的简单例子

现在虽然我们很少用到RMI进行编程，但是做为Java一个最早的分布式解决方案，我们还是有了解的必要，从例子开始吧（虽然是几年前的了）！

远程接口RmiHelloRemoteIntfc .java

import java.rmi.*;

public interface RmiHelloRemoteIntfc extends Remote
{
   String helloRemoteObj(String client) throws RemoteException;
}

远程接口的实现类RmiHelloRemoteObj.java

import java.rmi.server.*;
import java.rmi.*;

public class RmiHelloRemoteObj extends UnicastRemoteObject implements RmiHelloRemoteIntfc
{

  public RmiHelloRemoteObj() throws RemoteException
  {
    super();
  }

  public String helloRemoteObj(String client) throws RemoteException
  {
     return "Hello World"+client;
  }

}

服务器类RmiHelloServer.java

import java.io.*;
import java.rmi.*;
import java.rmi.server.*;
import sun.applet.*;
import java.rmi.registry.LocateRegistry;

public class RmiHelloServer
{

  public RmiHelloServer()
  {
  }
  public static void main(String[] args)
  {
    //创建并安装安全管理器
    if(System.getSecurityManager()==null)
    {
       System.setSecurityManager(new RMISecurityManager());
    }

    try{
         //创建远程对象
         RmiHelloRemoteObj ttt=new RmiHelloRemoteObj();
         //启动注册表
         LocateRegistry.createRegistry(2222);
         //奖名称绑定到对象
         Naming.rebind("//Fangm:2222/helloObj",ttt);

         System.out.println("RMI服务器正在运行。。。。。。");
      }
      catch(Exception e)
      {
         e.printStackTrace();
      }

  }
}

服务器端的权限文件RmiHelloServer.policy

grant codeBase
"file:/e:/download/rmitest/"
{
 permission java.net.SocketPermission
      "*:1000-9999","accept,connect,listen,resolve";
};

 

现在就看看Client端是如何连接服务器和进行远程方法的调用的吧

import java.rmi.*;
import java.rmi.server.*;

public class RmiHelloClient
{

  public RmiHelloClient()
  {
  }
  public static void main(String[] args)
  {
    //创建并安装安全管理器
    if(System.getSecurityManager()==null)
    {
       System.setSecurityManager(new RMISecurityManager());
    }

    try{
          RmiHelloRemoteIntfc c1=(RmiHelloRemoteIntfc)Naming.lookup("rmi://Fangm:2222/helloObj");
          System.out.println(c1.helloRemoteObj("Everyone"));
    }
    catch(Exception e)
    {
       e.printStackTrace();
    }
    System.exit(0);

 

  }
}

Client端的权限文件RmiHelloClient.policy

grant codeBase
"file:/e:/download/rmitest/"
{
  permission java.net.SocketPermission
      "*:1000-9999","accept,connect,listen,resolve";
};

好了，一个最简单的RMI例子就安无了，对了还少了最重要的一步，那就是编译和运行呢？我们就来了个Bat或Cmd的批处理来进行吧，

看看RmiHello.bat吧

javac RmiHelloRemoteIntfc.java

javac RmiHelloRemoteObj.java

rmic RmiHelloRemoteObj

javac RmiHelloServer.java

javac RmiHelloClient.java

echo 在另一个窗口启动服务器，请稍后。。。
start java  -Djava.security.policy=RmiHelloServer.policy RmiHelloServer

echo 运行客户程序。。。
java -Djava.security.policy=RmiHelloClient.policy RmiHelloClient