rmi.html

java 基础的 一点东西,,可以看看

the <CODE>RemoteServer</CODE> object that includes the
server name (<CODE>kq6py</CODE>) where the RMI Registry
and remote object run, and the name, <CODE>Send</CODE>.

<P>
By default the server name uses port 1099. If you
want to use a different port number, you can add it
with a colon as follows: <CODE>kq6py:4444</CODE>.
If you change the port here, you must start the
<A HREF="#registry">RMI Registry</A> with the same port number.

<P>
The <CODE>try</CODE> block creates an instance of
the <CODE>RemoteServer</CODE> class and binds the <CODE>name</CODE>
to the remote object to the RMI Registry with the
<CODE>Naming.rebind(name, remoteServer);</CODE> statement.

</FONT>

<PRE>
  public static void main(String[] args){
    if(System.getSecurityManager() == null) {
      System.setSecurityManager(new 
               RMISecurityManager());
    }
    String name = &quot;//kq6py.eng.sun.com/Send&quot;;
    try {
      Send remoteServer = new RemoteServer();
      Naming.rebind(name, remoteServer);
      System.out.println(&quot;RemoteServer bound&quot;);
    } catch (java.rmi.RemoteException e) {
      System.out.println(&quot;Cannot create 
                   remote server object&quot;);
    } catch (java.net.MalformedURLException e) {
      System.out.println(&quot;Cannot look up 
                   server object&quot;);
    }
  }
}
</PRE>

<FONT FACE="Verdana, Arial, Helvetica, sans-serif">


<BLOCKQUOTE>
<HR>
<STRONG>Note:</STRONG>
The <CODE>remoteServer</CODE> object is type
<CODE>Send</CODE> (see instance declaration at top of class)
because the interface available to clients is the
<CODE>Send</CODE> interface and its methods;
not the <CODE>RemoteServer</CODE> class and its
methods.
<HR>
</BLOCKQUOTE>

<A NAME="int"></A>
<H3>Send Interface</H3>

The <A HREF="./Code/Send.java">Send</A> interface declares the
methods implemented in the <CODE>RemoteServer</CODE>
class. These are the remotely accessible methods.

</FONT>

<PRE>
public interface Send extends Remote {

  public void sendData(String text) 
                throws RemoteException;
  public String getData() throws RemoteException;
}
</PRE>

<FONT FACE="Verdana, Arial, Helvetica, sans-serif">

<A NAME="first"></A>
<H3>RMIClient1 Class</H3>

The <A HREF="./Code/RMIClient1.java">RMIClient1</A> class establishes
a connection to the remote server program and sends
data to the remote server object. The code to do these things
is in the <CODE>actionPerformed</CODE> and <CODE>main</CODE> methods.

<H4>actionPerformed Method</H4>

The <CODE>actionPerformed</CODE> method calls the
<CODE>RemoteServer.sendData</CODE> method to send
text to the remote server object.

</FONT>

<PRE>
public void actionPerformed(ActionEvent event){
   Object source = event.getSource();

   if(source == button){
//Send data over socket
      String text = textField.getText();
      try{
        send.sendData(text);
      } catch (java.rmi.RemoteException e) {
        System.out.println(&quot;Cannot send data to server&quot;);
      }
      textField.setText(new String(&quot;&quot;));
   }
}
</PRE>

<FONT FACE="Verdana, Arial, Helvetica, sans-serif">

<H4>main Method</H4>

The <CODE>main</CODE> method installs the 
<CODE>RMISecurityManager</CODE> and creates a 
<CODE>name</CODE> to use to look up the 
<CODE>RemoteServer</CODE> server object. 
The client uses
the <CODE>Naming.lookup</CODE> method to look up
the <CODE>RemoteServer</CODE> object in the 
RMI Registry running on the server.  

<P>
The security manager determines whether there is a policy file
that lets downloaded code perform tasks that require permissions.

</FONT>

<PRE>
  RMIClient1 frame = new RMIClient1();

  if(System.getSecurityManager() == null) {
    System.setSecurityManager(new RMISecurityManager());
  }

  try {
//args[0] contains name of server where Send runs
    String name = &quot;//&quot; + args[0] + &quot;/Send&quot;;
    send = ((Send) Naming.lookup(name));
  } catch (java.rmi.NotBoundException e) {
    System.out.println(&quot;Cannot look up 
                 remote server object&quot;);
  } catch(java.rmi.RemoteException e){
    System.out.println(&quot;Cannot look up 
                 remote server object&quot;);
  } catch(java.net.MalformedURLException e) {
    System.out.println(&quot;Cannot look up 
                 remote server object&quot;);
  }
</PRE>

<FONT FACE="Verdana, Arial, Helvetica, sans-serif">

<A NAME="second"></A>
<H3>RMIClient2 Class</H3>

The <A HREF="./Code/RMIClient2.java">RMIClient2</A> class 
establishes a connection with the remote server program and 
gets the data from the remote server object
and displays it. The code to do this is in the
<CODE>actionPerformed</CODE> and <CODE>main</CODE> methods.

<H4>actionPerformed Method</H4>

The <CODE>actionPerformed</CODE> method calls the
<CODE>RemoteServer.getData</CODE> method to retrieve
the data sent by the client program.
This data is appended to the <CODE>TextArea</CODE>
object for display to the end user on the server side.

</FONT>

<PRE>
public void actionPerformed(ActionEvent event) {
   Object source = event.getSource();

   if(source == button){
      try{
        String text = send.getData();
        textArea.append(text);
      } catch (java.rmi.RemoteException e) {
        System.out.println(&quot;Cannot send data 
                     to server&quot;);
      }
      }
   }
}
</PRE>

<FONT FACE="Verdana, Arial, Helvetica, sans-serif">

<H4>main Method</H4>

The <CODE>main</CODE> method installs the
<CODE>RMISecurityManager</CODE> and creates a
<CODE>name</CODE> to use to look up the
<CODE>RemoteServer</CODE> server object. The
<CODE>args[0]</CODE> parameter provides the
name of the server host. The client uses
the <CODE>Naming.lookup</CODE> method to look up
the <CODE>RemoteServer</CODE> object in the
RMI Registry running on the server.

<P>
The security manager determines whether there is a policy file
that lets downloaded code perform tasks that require permissions.

</FONT>

<PRE>
  RMIClient2 frame = new RMIClient2();

  if(System.getSecurityManager() == null) {
    System.setSecurityManager(new RMISecurityManager());
  }

  try {
    String name = &quot;//&quot; + args[0] + &quot;/Send&quot;;
    send = ((Send) Naming.lookup(name));
  } catch (java.rmi.NotBoundException e) {
    System.out.println(&quot;Cannot look up remote 
                 server object&quot;);
  } catch(java.rmi.RemoteException e){
    System.out.println(&quot;Cannot look up remote 
                 server object&quot;);
  } catch(java.net.MalformedURLException e) {
    System.out.println(&quot;Cannot look up remote 
                 server object&quot;);
  }

</PRE>

<FONT FACE="Verdana, Arial, Helvetica, sans-serif">

<A NAME="more"></A>
<H3>More Information</H3>

You can find more information on the RMI API in the 
<A HREF="http://java.sun.com/docs/books/tutorial/rmi/index.html">RMI</A> 
trail of 
<A HREF="http://java.sun.com/docs/books/tutorial/index.html">The
Java Tutorial</A>.

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