java - 读写套接字，Java

Question

我在服务器/客户端 Java 应用程序中读取和写入套接字时遇到一点问题。服务器连接到数据库。我想将包含用户数据(姓名、姓氏、密码)的对象“员工”发送到服务器，然后服务器查找有关此用户的数据库并重新发送给客户端信息 - 正(1)或负(-1)。

首先，当我想发送一个对象 Employee 时，我有:“java.net.SocketException:软件导致连接中止:套接字写入错误”我关闭了防火墙。

其次，当我想通过 writeInt - readInt 方法发送和接收 int 进行测试时，我无法读取服务器上的任何内容。

有什么问题？请帮忙。

代码服务器:

class ClientCommunication implements Runnable {
    private Socket incoming;

    public ClientCommunication(Socket clientSocket) {
        incoming = clientSocket;

    }

    public void run() {
        try {
            synchronized (this) {
                try {                   
                    serverObjectOutput = new ObjectOutputStream(
                            incoming.getOutputStream());
                    serverObjectInput = new ObjectInputStream(
                            incoming.getInputStream()); 
                } finally {
                    incoming.close();
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

        synchronized(this) {
            while (true) {
                try{                        
                    int operation = serverObjectInput.readInt();                        

                    switch(operation) {
                    case 1:
                            Employee employee = (Employee) serverObjectInput.readObject();
                            String SelectUserDataSQL = "SELECT COUNT(*) AS COUNT FROM pracownik where Imie = ? AND Nazwisko = ? AND Haslo = ?";
                            PreparedStatement CheckEmployeeLogin;
                            CheckEmployeeLogin = conn.prepareStatement(SelectUserDataSQL);

                            CheckEmployeeLogin.setString(1, employee.getFirstName());
                            CheckEmployeeLogin.setString(2, employee.getLastName());
                            CheckEmployeeLogin.setString(3, new String(employee.getPassword()));                    

                            ResultSet resultSQL = CheckEmployeeLogin.executeQuery();
                            if (resultSQL.next()) 
                                if (resultSQL.getInt("COUNT") == 0)
                                    serverObjectOutput.writeInt(1);
                                else serverObjectOutput.writeInt(-1);
                            break;
                }
            } catch(IOException | ClassNotFoundException | SQLException ex)                 
            {                   
            }
          }
        }
    }
}

class ServerStart implements Runnable {
    private int portNumber;

    public ServerStart(int portNumber) {
        this.portNumber = portNumber;
    }

    public void run() {


        try {
            conn = getConnection();
            stat = conn.createStatement();

        } catch (SQLException e1) {             
            e1.printStackTrace();
        } catch (IOException e1) {              
            e1.printStackTrace();
        } catch (InterruptedException e) {              
            e.printStackTrace();
        }


        try {
            serverSocket = new ServerSocket(portNumber);                

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


        try {
            while (true) {
                Socket incoming = serverSocket.accept();

                clientSockets.add(incoming);

                Runnable r = new ClientCommunication(incoming);
                Thread t = new Thread(r);
                t.start();
            }
        } catch (IOException e) {
            e.printStackTrace();                
        }
    }       
}

代码客户端:

public void actionPerformed(ActionEvent e) {
                if (isConnected == false) {
                    String ServerIP = ip.getText().trim();

                    int ServerPort = Integer
                            .parseInt(port.getText().trim());


                    try {
                        ClientSocket = new Socket(ServerIP, ServerPort);                        

                        clientObjectInput = new ObjectInputStream(
                                ClientSocket.getInputStream());
                        clientObjectOutput = new ObjectOutputStream(
                                ClientSocket.getOutputStream());

                        isConnected = true;
                    } catch (IOException ex) {                          
                    }
                    synchronized (this) {
                        try {                               
                            ClientLoginFrame login = new ClientLoginFrame();

                            Employee employee = login.getEmployee();                                                                

                            clientObjectOutput.writeObject(employee);                               
                            int result = clientObjectInput.readInt();

                            if(result == 1)
                            {       
                                  // DO SOMETHING
                            }
                            else { 
                                ClientSocket.close();                                   
                            }                           
                        } catch (IOException ex) {
                            ex.printStackTrace();

                        }
                    }
                }
            }
        });
    }       

Answer 1

1. 添加一个 ex.printStackTrace() 来查看您的

   捕获(IOException | ClassNotFoundException | SQLException ex)

2. 服务器端，在您的 ClientCommunication 类上:您似乎在进入 while 循环之前关闭套接字。所以套接字已经关闭，无法发送/接收消息。您不应在此处调用 incoming.close()，而应在 run() 方法的末尾调用。