最简单的RMI调用示例

RMI是Remote Method Innovation的缩写，表示远程方法引进。

 

为不同机器之间提供服务。

第一步：定义接口。这个接口既是自己实现需要，也是远程需要的。两者定义应该是一样的。

 

 

package com.xiva.rmi;

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

/**
 * @Description 接口必须扩展Remote接口，其方法必须throws RemoteException
 * @author Administrator
 *
 */
public interface RoomService  extends Remote{

	public String getRoomName(Long roomId) throws RemoteException; ;
	
}

 

第二步：实现接口。实现接口并写一个main方法启动服务。

 

 

package com.xiva.rmi;

import java.rmi.RMISecurityManager;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
import java.rmi.server.UnicastRemoteObject;


/**
 * @Description 需要extends UnicastRemoteObject类
 * @author Administrator
 *
 */
public class RoomServiceImpl extends UnicastRemoteObject implements RoomService {

	protected RoomServiceImpl() throws RemoteException {
		super();
	}

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	@Override
	public String getRoomName(Long roomId) throws RemoteException{
		if(Long.valueOf(12l).equals(roomId)){
			return "废之间";
		}
		return "天之间";
	}
	
	public static void main(String[] args) {
		
		
//		System.setProperty("java.security.policy","*.policy");//设置安全策略  
		System.setSecurityManager(new RMISecurityManager());
		try { 
			Registry reg = LocateRegistry.createRegistry(2011); //注册服务端口
			RoomServiceImpl pt = new RoomServiceImpl(); 
			reg.rebind( "RoomService" , pt); //绑定服务名称
			System.out.println("Ready to do time"); 
		} catch(Exception e) { 
			e.printStackTrace(); 
		} 
	}

}

 

写好上面程序，就可以使用java来运行这个类了。

 

第三步，编写客户端程序。

 

 

package com.xiva.rmi.client;

import java.rmi.Naming;
import java.rmi.RMISecurityManager;

import com.xiva.rmi.RoomService;

public class CallRoom {

	public static void main(String[] args) { 
		System.setSecurityManager( new RMISecurityManager()); 
		try { 
			RoomService t = (RoomService)Naming.lookup( "rmi://192.168.0.16:2011/RoomService"); 
			System.out.println(t.getRoomName(11l));
		} catch(Exception e) { 
			e.printStackTrace(); 
		} 
	} 
}

 

当然写完这些程序，在一般情况下是可以运行的。比如我的机器就可以正常运行。

 

但是有时我们是还需要指定keystore的，主要与环境有关系。有的计算机某些端口访问是需要提供验证，一般部署环境都是这样。

 

相关安全策略的设置：

 

D:\Program Files\Java\jdk1.6.0_29\jre\lib\security\java.policy

 

 

// Standard extensions get all permissions by default

grant codeBase "file:${{java.ext.dirs}}/*" {
	permission java.security.AllPermission;
};

// default permissions granted to all domains

grant { 
	// Allows any thread to stop itself using the java.lang.Thread.stop()
	// method that takes no argument.
	// Note that this permission is granted by default only to remain
	// backwards compatible.
	// It is strongly recommended that you either remove this permission
	// from this policy file or further restrict it to code sources
	// that you specify, because Thread.stop() is potentially unsafe.
	// See the API specification of java.lang.Thread.stop() for more
        // information.stopThread
        //
	permission java.lang.RuntimePermission "accessClassInPackage.sun.jdbc.odbc";

   permission java.lang.RuntimePermission "stopThread";
   permission java.lang.RuntimePermission "modifyThreadGroup";
   permission java.lang.RuntimePermission "modifyThread";
   permission java.net.SocketPermission "*", "connect,accept,resolve";


	// allows anyone to listen on un-privileged ports
	permission java.net.SocketPermission "localhost:1024-", "listen";

	// "standard" properies that can be read by anyone

	permission java.util.PropertyPermission "java.version", "read";
	permission java.util.PropertyPermission "java.vendor", "read";
	permission java.util.PropertyPermission "java.vendor.url", "read";
	permission java.util.PropertyPermission "java.class.version", "read";
	permission java.util.PropertyPermission "os.name", "read";
	permission java.util.PropertyPermission "os.version", "read";
	permission java.util.PropertyPermission "os.arch", "read";
	permission java.util.PropertyPermission "file.separator", "read";
	permission java.util.PropertyPermission "path.separator", "read";
	permission java.util.PropertyPermission "line.separator", "read";

	permission java.util.PropertyPermission "java.specification.version", "read";
	permission java.util.PropertyPermission "java.specification.vendor", "read";
	permission java.util.PropertyPermission "java.specification.name", "read";

	permission java.util.PropertyPermission "java.vm.specification.version", "read";
	permission java.util.PropertyPermission "java.vm.specification.vendor", "read";
	permission java.util.PropertyPermission "java.vm.specification.name", "read";
	permission java.util.PropertyPermission "java.vm.version", "read";
	permission java.util.PropertyPermission "java.vm.vendor", "read";
	permission java.util.PropertyPermission "java.vm.name", "read";
   permission java.util.PropertyPermission "file.encoding", "read";
};

 

 

设置为上面安全策略。

 

createRegister后，可以使用RMIGetRegister 来获取registry，bind新的服务名

 

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package com.xiva;

import java.rmi.AlreadyBoundException;
import java.rmi.NotBoundException;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
import java.rmi.server.UnicastRemoteObject;

/**
 *
 * @author Administrator
 */
public class RMIGetRegister {
    
    private static Registry registry = null;
    
    private static String bindName = "RoomService";
    
     public static void main(String[] args) throws InterruptedException, RemoteException, AlreadyBoundException {
                 // 取得RMIRegistry
        try {
            registry = LocateRegistry.getRegistry(2012);
        } catch (RemoteException ex) {
            System.out.println(ex.getMessage());
        }
        
        // 解除Registry绑定
        try {
            System.out.println("trying to unbind rmi registry");
            registry.unbind(bindName);
            Thread.sleep(3000); //wait 3 seconds.
        } catch (RemoteException ex) {
            ex.printStackTrace();
        } catch (NotBoundException ex) {
            //nothing to do
        }
        
        RoomService o = new RemoteServiceImpl();
        //RemoteMethod  stub= (RemoteMethod) UnicastRemoteObject.exportObject(o, 0);
        registry.bind("xiva", o);
        System.out.println("bindName");
     }
}

 

注意UnicastRemoteObject.exportObject(o, 0)其中的o是没有extends UnicastRemoteObject的类。