bufferedreader（socket.getinputstream）readline（）方法不等待客户端输入

Question

我正在开发一个使用java的电子投票系统。客户端发送一个代表请求方法的数字。然后服务器线程的run（）方法根据发送的数字等待来自套接字的输入。该服务器为第一客户机请求通常读取输入，但是我从服务器获取以下异常：

异常在线程“线程0” java.lang.NumberFormatException：对于 输入字符串：“测试”在 java.lang.NumberFormatException.forInputString（Unknown Source）at java.lang.Integer.parseInt（Unknown Source）at java.lang.Integer.parseInt（Unknown Source）at ServerThread.run（ServerThread.java:139）

然后线程异常终止（我的结论是因为当我尝试从同一客户端GUI执行另一个操作，我得到一个SocketException：Socket被关闭）。 user = Integer.parseInt（in.readLine（））;应该等待另一个整数由客户端发送，但不是。它读取最后发送的字符串。 （IM使用BufferedReader类）

这里是serverthread的run方法：

public void run() { 
    while (true) { 
     int user = -1; 
     // while ((user = Integer.parseInt(in.readLine())) != -1) { 

     try { 
      user = Integer.parseInt(in.readLine()); 
     } catch (IOException e) { 
      System.out.println("Command Error"); 
     } 

     switch (user) { 
     case 1: 
      try { 
       String username = in.readLine(); 
       String password = in.readLine(); 
       int cid = -1; 
       Statement stmt = con.createStatement(); 
       ResultSet rs = stmt.executeQuery(
         "SELECT UUID FROM user_acc WHERE UUID IN (SELECT CID FROM candidate) AND username = '" 
           + username + "';"); 

       if (Security.Authenticate(username, password) && !username.equals("") && !password.equals("")) 
        out.println("true"); 
       else { 
        out.println("false"); 
       // in.reset(); 
        break; 
       } 
       if (rs.next()) { 
        cid = rs.getInt(1); 

        String inetAddress = clientSocket.getInetAddress().toString().substring(1); 
        stmt.executeUpdate(
          "UPDATE candidate SET ipadd = '" + inetAddress + "' WHERE CID = " + cid + ";"); 
       } 

      } catch (IOException e) { 
       System.out.println("Writing in Sign in Error"); 
      } catch (UserNotExistingException e) { 

      } catch (SQLException e) { 
       e.printStackTrace(); 
      } 
      break; 

     case 2: 
      try { 
       String username = in.readLine(); 
       String name = in.readLine(); 
       String password = in.readLine(); 
       String email = in.readLine(); 
       String conf = in.readLine(); 
       if (Security.signUp(username, name, email, password, conf)) 
        out.println("true"); 
       else 
        out.println("false"); 
      } catch (IOException e) { 
       System.out.println("Reading in Sign Up Error"); 
      } catch (UsernameEmailExistsException e) { 
       System.out.println("Email Exists"); 
       out.println("false"); 
      } 
      break; 

     case 3: 
      try { 
       String email = in.readLine(); 
       String code; 
       if (Security.forgotPass(email)) { 
        out.println("true"); 
        code = in.readLine(); 
       } else { 
        out.println("false"); 
        break; 
       } 

       if (Security.checkCode(code, email)) 
        out.println("true"); 
       else { 
        out.println("false"); 
        break; 
       } 
       String newpass = in.readLine(); 
       String conf = in.readLine(); 
       String username = ""; 
       for (int i = 0; i < email.length(); i++) 
        if (email.charAt(i) == '@') 
         break; 
        else 
         username += email.charAt(i); 

       if (Security.forceChangePassword(username, newpass, conf)) { 
        out.println("true"); 
       } else 
        out.println("false"); 
      } catch (IOException e) { 
       System.out.println("Reading in Forget Pass Error"); 
      } 
      break; 

     case 4: 
      try { 
       int CID = Integer.parseInt(in.readLine()), userID = Integer.parseInt(in.readLine()); 
       try { 
        if (nominate(CID, userID)) 
         out.println("true"); 
        else 
         out.println("false"); 
       } catch (ClassNotFoundException | SQLException | UserNotExistingException e) { 
        e.printStackTrace(); 
       } 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } 
      break; 

     case 5: 
      try { 
       int uid = Integer.parseInt(in.readLine()); 
       String candname = in.readLine(); 
       if (vote(candname, uid)) 
        out.println("true"); 
       else 
        out.println("false"); 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } 
      break; 

     case 6: 

      break; 

     case 7: 
      try { 
       String text = in.readLine(); 
       int UID = Integer.parseInt(in.readLine()); 
       int CID = Integer.parseInt(in.readLine()); 
       if (postComment(text, UID, CID)) 
        out.println("true"); 
       else 
        out.println("false"); 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } 
      break; 

     case 10: 
      try { 
       String username = in.readLine(); 
       String oldPass = in.readLine(); 
       String newPass = in.readLine(); 
       String conf = in.readLine(); 
       if (Security.changePass(username, oldPass, newPass, conf)) 
        out.println("true"); 
       else 
        out.println("false"); 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } 
      break; 

     case 11: 
      try { 
       int CID = Integer.parseInt(in.readLine()); 
       Statement stmt = con.createStatement(); 
       ResultSet rs = stmt.executeQuery("SELECT ipadd FROM candidate WHERE CID = " + CID + ";"); 
       if (rs.next()) 
        out.println(rs.getString(1)); 
       int port = Integer.parseInt(in.readLine()); 
       out.write(port); 

      } catch (IOException e) { 
       e.printStackTrace(); 
      } catch (SQLException e) { 
       e.printStackTrace(); 
      } 
      break; 

     } 
    } 
} 

这里是我的客户端方法（如果问题出在他们）：

public class Client { 
    private static Socket clientSocket; 
    private final int PORT_NUM = 4373; 
    private static DataOutputStream p2pout; 
    private String IP; 

    public Client(String IP) throws IOException { 
     this.IP = IP; 
     try { 
      clientSocket = new Socket(IP, PORT_NUM); 

     } catch (Exception e) { 
      System.err.println("Cannot connect to the server, try again later."); 
      System.exit(1); 
     } 
    } 

    public void sendCommand(int com) throws IOException { 
     BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); 
     PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true); 
     out.println(com + ""); 
     out.close(); 
     in.close(); 
    } 

    public static boolean SignIn(String Username, String password) throws IOException { 
     BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); 
     PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true); 
     out.println(1); 
     out.println(Username); 
     out.println(password + "\n"); 
     String reply = in.readLine(); 
     out.close(); 
     in.close(); 
     if (reply.equals("true")) 
      return true; 
     else 
      return false; 
    } 

    public static boolean SignUp(String Username, String name, String email, String password, String conf) 
      throws IOException { 
     BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); 
     PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true); 
     out.println(2); 
     out.println(Username); 
     out.println(name); 
     out.println(password); 
     out.println(email); 
     out.println(conf); 
     String reply = in.readLine(); 
     out.close(); 
     in.close(); 
     if (reply.equals("true")) 
      return true; 
     else 
      return false; 
    } 

    public static boolean ForgetPass(String email) throws IOException { 
     BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); 
     PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true); 
     out.println(3); 
     out.println(email); 
     String reply = in.readLine(); 
     if (reply.equals("true")) 
      return true; 
     else 
      return false; 
    } 

    public static boolean ForgetPass2(String code) throws IOException { 
     BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); 
     PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true); 
     out.println(3); 
     out.println(code); 
     String reply = in.readLine(); 
     if (reply.equals("true")) 
      return true; 
     else 
      return false; 
    } 

    public static boolean ForgetPass3(String newpass, String conf) throws IOException { 
     BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); 
     PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true); 
     out.println(newpass); 
     out.println(conf); 
     String reply = in.readLine(); 
     out.close(); 
     in.close(); 
     if (reply.equals("true")) 
      return true; 
     else 
      return false; 
    } 

    public static boolean nominate(int CID, int UserID) throws IOException { 
     BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); 
     PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true); 
     out.println(4); 
     out.println(CID + ""); 
     out.println(UserID + ""); 
     String reply = in.readLine(); 
     out.close(); 
     in.close(); 
     if (reply.equals("true")) 
      return true; 
     else 
      return false; 
    } 

    public static boolean vote(int cid, int UID) throws IOException { 
     BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); 
     PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true); 
     out.println(5); 
     out.println(cid); 
     out.println("" + UID); 
     String reply = in.readLine(); 
     out.close(); 
     in.close(); 
     if (reply.equals("true")) 
      return true; 
     else 
      return false; 
    } 

    public static boolean postcomment(int CID, String text, int UID) throws IOException { 
     BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); 
     PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true); 
     out.println(7); 
     out.println(text + ""); 
     out.println(UID + ""); 
     out.println(CID + ""); 
     String reply = in.readLine(); 
     out.close(); 
     in.close(); 
     if (reply.equals("true")) 
      return true; 
     else 
      return false; 
    } 

    public static boolean Changepass(String Username, String oldpass, String newpass, String conf) throws IOException { 
     BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); 
     PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true); 
     out.println(10); 
     out.println(Username); 
     out.println(oldpass); 
     out.println(newpass); 
     out.println(conf); 
     String reply = in.readLine(); 
     out.close(); 
     in.close(); 
     if (reply.equals("true")) 
      return true; 
     else 
      return false; 
    } 

    public String getIPAddress(int cid) throws IOException { 
     BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); 
     PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true); 
     out.println(11); 
     out.println(cid + ""); 
     String inetAddress = in.readLine(); 
     out.close(); 
     in.close(); 
     return inetAddress; 
    } 

    public int getServerChatPort() throws IOException { 
     BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); 
     PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true); 
     int port = Integer.parseInt(in.readLine()); 
     out.close(); 
     in.close(); 
     return port; 
    } 

    public static void connectionListener(String inetadd) { 
     try { 
      BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); 
      PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true); 
      ServerSocket ss = new ServerSocket(0); 
      Socket clientSocket = ss.accept(); 
      out.println(ss.getLocalPort() + ""); 
      Socket candSock = ss.accept(); 
      ChatListener cl = new ChatListener(candSock); 
      cl.start(); 
      out.close(); 
      in.close(); 
      while (true) { 
       if (ChatListener.flag == 1) 
        cl.display(); 
       // ^^ Displayed in GUI 
      } 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 

    } 

    public Socket chatConnect(String inetAdd) { 
     Socket soc = null; 
     try { 
      int port = getServerChatPort(); 
      soc = new Socket(inetAdd, port); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 
     return soc; 
    } 

    public void send(String m) { 

     try { 
      p2pout.writeChars(m); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 
    } 

    public void close() throws IOException { 
     clientSocket.close(); 
    } 
} 

Answer 1

的根问题是每次操作后套接字关闭。那么代码会关闭连接到套接字的输出流，但关闭从getOutputStream()返回的流也会关闭相关的套接字。

随后的客户端发送尝试失败，因为套接字已关闭，并且服务器因接收操作（readLine()）中断且未收到数据而失败。

尝试保持客户端输出流处于打开状态。你可以创建一个像Socket或类似的类属性。