java RMI

   RMI限java之间，且使用Stream 技术(serialize）传输。WebService是通过XML来传输数据，可用http等协议因此可在异构系统间传递，并且可以穿过防火墙，可在公网上远程调用。
(1)远程调用接口

import java.rmi.Remote;
import java.rmi.RemoteException;
public interface ComputerEngineRemote extends Remote {
    public Object excuteTask(Task task) throws RemoteException;

}

(2)远程调用接口实现

public class ComputerEngine extends UnicastRemoteObject implements
        ComputerEngineRemote {

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

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

    public Object excuteTask(Task task) throws RemoteException {
        return task.excute();
    }

}

(3)定义业务接口

public interface Task extends Serializable {
    Object excute();

}

(2)业务接口实现

public class TaskImpl implements Task {

	private static final long serialVersionUID = 1L;

	public Object excute() {
        return "Successful!";
    }

}

(4)将远程对象注册到 RMI 的注册表

public class Bootstrap {

/*  "引导"过程（Bootstrap）。引导程序负责创建和注册远程对象。*/
public static void main(String[] args) throws Exception {
         String name="ComputerEngine";
        //System.setProperty("java.rmi.server.hostname","172.31.3.33");
        //System.setProperty( "java.security.policy", "client.policy" );
        //System.setSecurityManager(new java.rmi.RMISecurityManager());
    	LocateRegistry.createRegistry(1099);     
    	ComputerEngine server = new ComputerEngine(); 
    	Naming.rebind("rmi://127.0.0.1:1099/ComputerEngine", server); 
    	System.out.println("Ready to accept tasks"); 

    	}
}

(5)远程调用接口

public class Client {

    public static void main(String[] args) throws Exception {
        String name="rmi://127.0.0.1:1099/ComputerEngine";
        try{
           //定义接口
           ComputerEngineRemote engineRemote=(ComputerEngineRemote) Naming.lookup(name);
           System.out.println(engineRemote.excuteTask(new TaskImpl()));
           }catch(ConnectException e){
    	   e.printStackTrace();
    	   System.out.println("No listener!");
       }

    }

}

(6)java.policy

permission java.net.SocketPermission "127.0.0.1:1099","connect,resolve";

permission   java.security.AllPermission;
  
   Java应用程序环境的安全策略，详细说明了对于不同的代码所拥有的不同资源的许可，它由一个Policy对象来表达。为了让applet（或者运行在   SecurityManager下的一个应用程序）能够执行受保护的行为，例如读写文件，applet（或   Java应用程序）必须获得那项操作的许可,安全策略文件就是用来实现这些许可。
grant   {    
  //对系统和用户目录“读”的权限    
  permission   java.util.PropertyPermission   “user.dir",   “read";    
  permission   java.util.PropertyPermission   “user.home",   “read";    
  permission   java.util.PropertyPermission   “java.home",   “read";    
  permission   java.util.PropertyPermission   “java.class.path",   “read";    
  permission   java.util.PropertyPermission   “user.name",   “read";    
   
  //对线程和线程组的操作权限    
  permission   java.lang.RuntimePermission   “modifyThread";    
  permission   java.lang.RuntimePermission   “modifyThreadGroup";    
   
  //操作Socket端口的各种权限    
  permission   java.net.SocketPermission   “－",   “listen";    
  permission   java.net.SocketPermission   “－",   “accept";    
  permission   java.net.SocketPermission   “－",   “connect";    
  permission   java.net.SocketPermission   “－",   “read";    
  permission   java.net.SocketPermission   “－",   “write";    
   
  //读写文件的权限    
  permission   java.io.FilePermission   “－",   “read";    
  permission   java.io.FilePermission   “－",   “write";    
   
  //退出系统的权限，例如System.exit(0)    
  permission   java.lang.RuntimePermission   “exitVM";    
};    

(7)远程调用，得到图片文件

Remote:

public Object excute() {
		String inputFile="D:/images/img.bmp";
		FileInputStream source=null;
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
		try {
			source = new FileInputStream(new File(inputFile));
		    int bytes_read;
		    byte[] buffer = new byte[1024];
		    while (true) {
		        bytes_read = source.read(buffer);
		        if (bytes_read == -1) {
		          break;
		        }
		        bos.write(buffer, 0, bytes_read);
		    }
	        byte[] data = bos.toByteArray();
	        bos.close();
	        bos = null;
	        return data;
        }catch(Exception e){
            
        }finally{
            if(bos != null){
                try {
					bos.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
                bos = null;
            }
        }
        return null;
}

Client:

public static void main(String[] args) throws Exception {
        String name="rmi://127.0.0.1:1099/ComputerEngine";
       try{
    	   ComputerEngineRemote engineRemote=(ComputerEngineRemote) Naming.lookup(name);
    	   File outputFile = new File("D:/images/receive.bmp");
		   FileOutputStream target = new FileOutputStream(outputFile);
		   target.write((byte[])engineRemote.excuteTask(new TaskImpl()));
		   System.out.println("OK!");
       }catch(ConnectException e){
    	   e.printStackTrace();
    	   System.out.println("No listener!");
       }
}

评论

1 楼 Motte2010 2012-03-08  

远程对象注册到 RMI 的注册表  这步报错  楼主没有遇到这问题？

java.rmi.StubNotFoundException: Stub class not found: server.TaskRemoteImp_Stub; nested exception is: 
	java.lang.ClassNotFoundException: server.TaskRemoteImp_Stub
	at sun.rmi.server.RemoteProxy.getStub(RemoteProxy.java:98)
	at sun.rmi.server.RemoteProxy.getStub(RemoteProxy.java:55)
	at sun.rmi.server.UnicastServerRef.setSkeleton(UnicastServerRef.java:179)
	at sun.rmi.server.UnicastServerRef.exportObject(UnicastServerRef.java:142)
	at sun.rmi.server.UnicastServerRef.exportObject(UnicastServerRef.java:129)
	at java.rmi.server.UnicastRemoteObject.exportObject(UnicastRemoteObject.java:275)
	at java.rmi.server.UnicastRemoteObject.exportObject(UnicastRemoteObject.java:178)
	at java.rmi.server.UnicastRemoteObject.<init>(UnicastRemoteObject.java:75)
	at java.rmi.server.UnicastRemoteObject.<init>(UnicastRemoteObject.java:61)
	at server.TaskRemoteImp.<init>(TaskRemoteImp.java:13)
	at rmiMain.main(rmiMain.java:15)
Caused by: java.lang.ClassNotFoundException: server.TaskRemoteImp_Stub
	at java.net.URLClassLoader$1.run(URLClassLoader.java:199)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:187)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:289)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:274)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:235)
	at sun.rmi.server.RemoteProxy.loadClassFromClass(RemoteProxy.java:191)
	at sun.rmi.server.RemoteProxy.getStub(RemoteProxy.java:93)
	... 10 more
Exception in thread "main" 

是按照楼主所写的那样操作的啊