Java套接字凍結

我試圖實現一個簡單的服務器（Java應用程序）和客戶端（Android應用程序），其中客戶端每秒發送一個字符串約10次。一切正常工作一分鐘左右，之後服務器停止接收來自客戶端的消息。下面的相關代碼。Java套接字凍結

Thread clientThread = new Thread(new ClientThread(message)); 
clientThread.start();

ServerThread.jav：

ClientThread.java

public class ClientThread implements Runnable{ 
static Socket socket; 
static String message = ""; 
InetAddress serverAddr; 
BufferedOutputStream bos; 

public ClientThread(String message){ 
    ClientThread.message = message; 
} 

@Override 
public void run() { 
    try{ 
     serverAddr = InetAddress.getByName(SERVER_IP); 
     if(socket != null && socket.isConnected())socket.close(); 
     socket = new Socket(serverAddr, SERVER_PORT); 
     bos = new BufferedOutputStream (socket.getOutputStream()); 
     OutputStreamWriter osw = new OutputStreamWriter(bos, "US-ASCII"); 
     osw.write(message); 
     osw.flush(); 
     socket.shutdownOutput(); 
     socket.close(); 
    }catch (Exception e) { 
    } 
} 
}

ServerThread.java

public class ServerThread extends Thread{ 
    private ServerSocket serverSocket; 
    static String clientSentence; 

    public ServerThread(int port) throws IOException, AWTException{ 
     serverSocket = new ServerSocket(port); 
    } 

    public void run() { 
     while(true){ 
     try{ 
      Socket server = serverSocket.accept(); 
      BufferedReader d = new BufferedReader(new InputStreamReader(server.getInputStream())); 
      clientSentence = d.readLine(); 
      System.out.println(clientSentence); 
      server.close(); 
     }catch(IOException e){ 
      e.printStackTrace(); 
      break; 
     } 
     } 
    } 
}

ClientThread.java使用稱爲約10倍的第二a被初始化並開始使用：