Question

嘿伙计们。我试图在java中编写文件传输应用程序，到目前为止一切正常：我启动服务器和客户端，然后传输文件。我在将多个客户端连接到同一台服务器时遇到问题。我google了它，发现我的服务器端应该在线程中运行。我怎么能用我的申请呢？感谢。

服务器：

package filesharing;
import java.io.*;
import java.net.*;

public class Server
{
    public static void main(String args[])throws Exception
    {
        System.out.println("Server pornit...");

        /* Asteapta pe portul  1412 */

        ServerSocket server = new ServerSocket(1412);

        /* Accepta socketul */

        Socket sk = server.accept();

        System.out.println("Client acceptat de catre server pe portul: "+server.getLocalPort());
        InputStream input = sk.getInputStream();
        BufferedReader inReader = new BufferedReader(new InputStreamReader(sk.getInputStream()));
        BufferedWriter outReader = new BufferedWriter(new OutputStreamWriter(sk.getOutputStream()));

        /* Citeste calea fisierului */
        String filename = inReader.readLine();

        if ( !filename.equals("") ){

            /* Trimite status READY catre client */

            outReader.write("READY\n");
            outReader.flush();
        }

        /* Creaza fila noua in directorul tmp */
        FileOutputStream wr = new FileOutputStream(new File("C://tmp/" + filename));

        byte[] buffer = new byte[sk.getReceiveBufferSize()];

        int bytesReceived = 0;

        while((bytesReceived = input.read(buffer))>0)
        {
            /* Scrie in fila */
           wr.write(buffer,0,bytesReceived);
        }
    }
}

客户端：

package filesharing;

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.net.*;
import java.io.*;

public class Client extends JFrame implements ActionListener {

    private JTextField txtFile;

    public static void main(String args[]){

        /* Creare pannel client */

        Client clientForm = new Client();
        clientForm.Display();
    }

    public void Display(){

        JFrame frame = new JFrame();
        frame.setTitle("Client");

        FlowLayout layout = new FlowLayout();
        layout.setAlignment(FlowLayout.LEFT);

        JLabel lblFile = new JLabel("Fisier:");

        txtFile = new JTextField();
        txtFile.setPreferredSize(new Dimension(150,30));

        JButton btnTransfer = new JButton("Transfer");
        btnTransfer.addActionListener(this);

        JPanel mainPanel = new JPanel();
        mainPanel.setLayout(layout);
        mainPanel.add(lblFile);
        mainPanel.add(txtFile);
        mainPanel.add(btnTransfer);

        frame.getContentPane().add(mainPanel);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setVisible(true);

    }

    public void actionPerformed(ActionEvent e) {

        /* Casuta File Open Dialog pentru selectarea fisierului */

        JFileChooser fileDlg = new JFileChooser();
        fileDlg.showOpenDialog(this);
        String filename = fileDlg.getSelectedFile().getAbsolutePath();
        txtFile.setText(filename);

        try{

            /* Incearca conectarea la serverul localhost pe portul 1412 */

            Socket sk = new Socket("localhost", 1412);
            OutputStream output = sk.getOutputStream();

            /* Trimite numele fisierului la server */

            OutputStreamWriter outputStream = new OutputStreamWriter(sk.getOutputStream());
            outputStream.write(fileDlg.getSelectedFile().getName() + "\n");
            outputStream.flush();

            /* Asteapta raspunsul de la server */

            BufferedReader inReader = new BufferedReader(new InputStreamReader(sk.getInputStream()));

            String serverStatus = inReader.readLine(); // Citeste prima linie

            /* Daca serverul e READY trimite fisierul */

            if ( serverStatus.equals("READY") ){

                FileInputStream file = new FileInputStream(filename);

                byte[] buffer = new byte[sk.getSendBufferSize()];

                int bytesRead = 0;

                while((bytesRead = file.read(buffer))>0)
                {
                    output.write(buffer,0,bytesRead);
                }

                output.close();
                file.close();
                sk.close();

                JOptionPane.showMessageDialog(this, "Transfer complet");

            }
        }
        catch (Exception ex){
            /* Catch pentru eventuale erori */
            JOptionPane.showMessageDialog(this, ex.getMessage());
        }
    }
}

Answer 1

如果您想要处理在单个线程中运行每个服务器请求所需的多个连接，那么您是对的。背后的理论如下......

while (true)
    accept a connection ;
    create a thread to deal with the client ;
end while

或更多java-alike：

while(true) {
     clientSocket = serverSocket.accept();
     YourWorkerThread thread = new YourWorkerThread(clientSocket);
     thread.start();
}

哪里...... YourWorkerThread是一个扩展Thread并实现服务器逻辑所在的方法run的类。

因此，查看服务器端代码，Socket sk = server.accept();之后的所有代码行都应该放在扩展run的类的Thread方法中。

Answer 2

您可以使用Runnable实现接口new Thread(myRunnable).start()并启动实际工作 - 这是简单版本。确保您的代码是线程安全的，否则会干扰您的其他线程。

Answer 3

要define and start a thread，您需要传递到Runnable实例的Thread类的实现。

start非常相似，会为您提供一个开始的地方。一个答案指向This question。如果您还没有阅读过Socket教程，那么你肯定应该这样做。

但是，不要仅仅知道线程的基础知识，否则你会遇到问题。并发是一个难题。您将想要了解a socket tutorial that shows how to use multiple clients的伟大世界。

理想情况下，您将获得足够的灵感来阅读Java concurrency，这是Java中并发性的一个惊人参考。

Java应用程序中的线程

3 个答案: