Java - 用ObjectInputStream監聽套接字

Question

好吧，我有一個線程類叫做'客戶端'，每當服務器接受連接時它會創建一個新的客戶端....運行方法監聽來自客戶端的消息，我我期運用ObjectInputStream的..

do {    
     ObjectInputStream in = null; 

     try { 
      in = new ObjectInputStream(socket.getInputStream()); 
      String message = (String) in.readObject(); 
      System.out.println(message); 
      } 
      catch (ClassNotFoundException ex) { 
       isConnected = false; 
       System.out.println("Progoramming Error"); 
      } 
      catch (IOException ex) { 
       isConnected = false; 
       System.out.println("Server ShutDown"); 
       System.exit(0); 
      } 
    } while(isConnected); 

這個問題我有是，爲什麼我要創建一個新的ObjectInputStream每次循環的時間......如果我在循環結束時關閉輸入流，並循環再次爲另一個消息，我會得到一個錯誤...請幫助一下

Answer 1

只爲客戶端連接創建ObjectInputStream一次（循環外），然後把將readObject方法放入循環中。

這裏的工作測試類：

public class TestPrg { 

    public static void main(String... args) throws IOException { 
     ServerListener server = new ServerListener(); 
     server.start(); 

     Socket socketToServer = new Socket("localhost", 15000); 
     ObjectOutputStream outStream = new ObjectOutputStream(socketToServer.getOutputStream()); 

     for (int i=1; i<10; i++) { 
      try { 
       Thread.sleep((long) (Math.random()*3000)); 
      } catch (InterruptedException e) { 
       e.printStackTrace(); 
      } 
      System.out.println("Sending object to server ..."); 
      outStream.writeObject("test message #"+i); 
     } 
     System.exit(0); 

    } 

    static class ServerListener extends Thread { 

     private ServerSocket serverSocket; 

     ServerListener() throws IOException { 
      serverSocket = ServerSocketFactory.getDefault().createServerSocket(15000); 
     } 

     @Override 
     public void run() { 
      while (true) { 
       try { 
        final Socket socketToClient = serverSocket.accept(); 
        ClientHandler clientHandler = new ClientHandler(socketToClient); 
        clientHandler.start(); 
       } catch (IOException e) { 
        e.printStackTrace(); 
       } 
      } 
     } 
    } 

    static class ClientHandler extends Thread{ 
     private Socket socket; 
     ObjectInputStream inputStream; 

     ClientHandler(Socket socket) throws IOException { 
      this.socket = socket; 
      inputStream = new ObjectInputStream(socket.getInputStream()); 
     } 

     @Override 
     public void run() { 
      while (true) { 
       try { 
        Object o = inputStream.readObject(); 
        System.out.println("Read object: "+o); 
       } catch (IOException e) { 
        e.printStackTrace(); 

       } catch (ClassNotFoundException e) { 
        e.printStackTrace(); 
       } 
      } 
     } 
    } 

} 

在這個例子中的字符串被送到低谷ObjectStream。如果您得到ClassNotFoundException（http://download.oracle.com/javase/6/docs/api/java/io/ObjectInputStream.html#readObject（））並且正在使用獨立的客戶端和服務器程序，則可能會檢查是否客戶端和服務器都有要在其類路徑中發送的對象的類。