无法在Java中运行多线程服务器程序

这是服务器代码

package echoserver;

import java.net.*;
import java.io.*;

public class EchoServer {

    public static void main(String[] args) {
        try {

            //establish server socket
            ServerSocket s = new ServerSocket(1981);

            //Thread client connectionsincoming
            while (true) {
                //wait for incoming connection
                Socket incoming = s.accept();
                Runnable r = new ThreadedEchoHandler(incoming);
                Thread t = new Thread(r);
                t.start();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}


package echoserver;

import java.net.*;
import java.util.*;
import java.io.*;

class ThreadedEchoHandler implements Runnable {

    public ThreadedEchoHandler(Socket i) {
        //initializing socket
        incoming = i;
    }

    public void run() {
        try {
            try {
                //recieve input stream from socket
                InputStream inStream = incoming.getInputStream();

                //recieve output stream from socket
                OutputStream outStream = incoming.getOutputStream();

                //Create a scanner from input stream
                Scanner scan = new Scanner(inStream);

                //Create printer writer from output stream and enabled auto flushing
                PrintWriter out = new PrintWriter(outStream, true);

                //prompt users on how to exit program soon as a long in into the server
                out.println("Enter BYE to exit");

                boolean done = false;

                //while done is not true and scanner has next line loop
                while (!done && scan.hasNextLine()) {

                    //reading text that came in from the socket
                    String line = scan.nextLine();

                    //On the server print the ip address of where the text is coming from and the text they typed
                    System.out.println("Recieved from " + incoming.getInetAddress().getHostAddress() + ": " + line);

                    //Echo back the text the client typed to the client
                    out.println("Echo: " + line);

                    //if they type BYE in caps terminate there connection and I also trimmed whitespaces
                    if (line.trim().equals("BYE")) {
                        done = true;
                    }
                }
            } //finally close the socket connection
            finally {
                incoming.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    private Socket incoming;
}

这是客户端的代码

package client;

import java.net.*;
import java.io.*;

public class Client {

    public static void main(String[] args) throws IOException {
        PrintWriter out = null;
        try {
            Socket s = new Socket(InetAddress.getLocalHost(), 1981);
            System.out.println("Connected to server on port 1981");
            out = new PrintWriter(s.getOutputStream());

            out.println("Hello");
            s.close();

        } catch (Exception ex) {
            System.err.println(ex.getMessage());
        }
    }
}

sockets已成功创建，但当控件转到t.start（）方法调用时，它没有调用ThreadedEchoHandler类的run（）方法

---

为什么会这样？有什么想法吗？

我猜acept语句会永远阻塞，因为没有客户端连接到服务器。您可以将accept（）包装在打印件中以证明或反驳。

客户机将

“Hello”

写入

PrintWriter

。到目前为止，一切顺利

您可能希望，

PrintWriter

会将此文本直接发送到套接字，但它不会。

PrintWriter（OutputStream）

构造函数中的文档说明，它创建了一个

PrintWriter

，而无需自动换行。这意味着您必须在需要实际发送某些内容时调用

out.flush（）

---

在您调用

out.flush（）

之前，文本只存在于某个内部缓冲区中，服务器将无法看到它。

如果我们尝试调试它，则控制转到t.start（），然后再次转到s.accept（）。它不叫跑步method@Nilesh巴拉伊，你怎么知道的？如果使用调试器单步执行代码，则不会，调试器不会切换到新创建的线程，您必须在该代码中设置断点。找到它。。。它正在调用run方法。在while循环scan.hasNextLine（）中的run（）方法中，没有要扫描的内容，它退出。所以我认为客户有问题