server.java

《JAVA分布式程序设计》一书的源代码。

import java.io.*;
import java.net.*;
import java.security.*;

/**
 * @(#)Server.java
 * @author Qusay H. Mahmoud
 */

public class Server implements Cloneable, Runnable {
   ServerSocket service = null;
   Socket clientSocket = null;
   ObjectInputStream ois = null;
   Thread worker = null;
   KeyPairGenerator kgen;
   KeyPair kpair;


   public static void main(String argv[]) throws IOException {
      Server serv = new Server();
      serv.startServer();
   }
           
   public synchronized void startServer() throws IOException {
      if (worker == null) {
	service = new ServerSocket(4000);
        worker = new Thread(this);
	worker.start();
      }
   }

   public void run() {
     Socket client = null;
     if (service != null) { // original or clone?
       while(true) {
         try {
           client = service.accept();
	   Server newServer = (Server) clone();
	   newServer.service = null;
	   newServer.clientSocket = client;
	   newServer.worker = new Thread(newServer);
	   newServer.worker.start();
	 } catch(IOException e) {
	   e.printStackTrace();
	 } catch(CloneNotSupportedException e) {
	  e.printStackTrace();
         }
       }
     } else {
         perform(clientSocket);
     }       
   }

   private void perform(Socket client) {
     try {
       ois = new ObjectInputStream(clientSocket.getInputStream());
       // read object from client
       SignedObject obj = (SignedObject) ois.readObject();
       // generate object's signature
       Signature sig = Signature.getInstance("SHA/DSA");
       sig.initVerify(obj.pub);
       sig.update(obj.b);
       
       // verify the signature
       boolean valid = sig.verify(obj.sig);
       if (valid) {
         System.out.println("Signature is valid");
       } else {
         System.out.println("Signature is not valid .... spy");
       }
     } catch(Exception e) {
       e.printStackTrace();
     }

     // close streams and connection
     try {
       ois.close();
       clientSocket.close();
     } 
     catch(IOException ex) {
        ex.printStackTrace();
     }
   }

}