JAVA-套接字:: readline（）什么也没做

Question

I created a Network-class where I open a socket an than send requests to it.

The class:

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

public class Network implements Runnable {
    private boolean isHost = false;

    private int hostPort = 19250;
    private int clientPort = 19251;
    private String host = "127.0.0.1";
    private String name = "";

    private ServerSocket ownServer = null;
    private Socket otherServer = null;
    private DataOutputStream outToServer = null;
    private BufferedReader inFromServer = null;
    private boolean isConnected = false;

    /**
     * Konstruktor -
     */
    Network(String name) {
        this.name = name;
        this.findHost();
        // if no host exists, become host itself
        if (this.isHost == false) {
            // host da -> become client
            System.out.println(this.name + ": host found");
            try {
                ownServer = new ServerSocket(this.clientPort);
            } catch (Exception e) {
                e.printStackTrace();
            }
        } else {
            // kein host da -> become host
            System.out.println(this.name + ": no host found");

            try {
                ownServer = new ServerSocket(this.hostPort);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

    }

    /**
     * connect() - versucht mit anderem server zu connecten fals dies noch nicht
     * geschehen ist
     * 
     * @return true/false
     */
    public boolean connect() {

        if (this.isConnected == false) {
            try {
                if (this.isHost) {
                    otherServer = new Socket(this.host, this.clientPort);
                } else {
                    otherServer = new Socket(this.host, this.hostPort);
                }
            } catch (IOException e) {
                //System.out.println(this.name + ": connect failed");
                this.isConnected = false;
                return false;
            }
        }

        try {
            outToServer = new DataOutputStream(otherServer.getOutputStream());
            inFromServer = new BufferedReader(new InputStreamReader(
                    otherServer.getInputStream()));
        } catch (IOException e) {
            e.printStackTrace();
        }

        //System.out.println(this.name + ": connect sucess");
        this.isConnected = true;
        return true;
    }

    /**
     * findHost() - schaut ob ein Host existiert
     * 
     * @return true/false
     */
    private boolean findHost() {
        Socket hostSocket;
        try {
            hostSocket = new Socket(this.host, this.getHostPort());
            DataOutputStream outToServer = new DataOutputStream(
                    hostSocket.getOutputStream());
            BufferedReader inFromServer = new BufferedReader(
                    new InputStreamReader(hostSocket.getInputStream()));
            outToServer.writeBytes("uHost?\n");// Fragen ob Host ist
        } catch (Exception e) {
            this.isHost = true;
            return false; // Keine Connection aufgebaut => kein Host vorhanden
        }
        this.isHost = false;
        return true; // Es gibt schon einen Host
    }

    public int getClientPort() {
        return this.clientPort;
    }

    public int getHostPort() {
        return this.hostPort;
    }

    public boolean getIsHost() {
        return this.isHost;
    }

    /**
     * sendToOther() - schickt daten an anderen Server
     * 
     * @param data
     */
    public void sendToOther(String data) {
        this.connect();
        try {
            this.outToServer.writeBytes(data);
            this.outToServer.writeBytes("\n"); //new Line
            this.outToServer.flush();
            System.out.println(this.name + ": " + data
                    + " :: send to other server");

        } catch (IOException e) {
            e.printStackTrace();
        }
        try {
            this.outToServer.flush();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        // listen to income
        String line = "";
        try {
            while (true) {
                System.out.println(this.name + ":111");
                while ((line = inFromServer.readLine())!= null) {
                    System.out.println(this.name + ":222");
                    System.out.println(this.name + ":recieved: " + line);
                }
                System.out.println(this.name + ":333");
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public void readAndDo(String data) {
        System.out.println(this.name + ": data recieved: " + data);
    }

}

The main Method:

public class Application {

    public static void main(String[] args) {
        Network t1net=new Network("ss1");
        Network t2net=new Network("ss2");
        t1net.connect();
        t2net.connect();


        t1net.sendToOther("some text1");
        t2net.sendToOther("sometext2");



        Thread t1 = new Thread( t1net );
        t1.start();


        Thread t2 = new Thread( t2net );
        t2.start();
    }

}

the console:

ss1: no host found
ss2: host found
ss1: some text1 :: send to other server
ss2: sometext2 :: send to other server
ss2:111
ss1:111

netstat -a:

  TCP    127.0.0.1:19250        49on41PCX:54538        HERGESTELLT
  TCP    127.0.0.1:19250        49on41PCX:54540        HERGESTELLT
  TCP    127.0.0.1:19251        49on41PCX:54539        HERGESTELLT
  TCP    127.0.0.1:49156        49on41PCX:0            ABHÖREN
  TCP    127.0.0.1:54538        49on41PCX:19250        HERGESTELLT
  TCP    127.0.0.1:54539        49on41PCX:19251        HERGESTELLT
  TCP    127.0.0.1:54540        49on41PCX:19250        HERGESTELLT

The problem is, that the Network.run() block in the readline()-command. The data is send, bu never recieved.

Thank you for helping.

Answer 1

You have used the sockets in a wrong manner.

ss : ServerSocket

s : Socket

You have first made two ss on two threads and made two s connecting to the the intial ss . In this way ss1 is bound to s2 and ss2 is bound to s1 . And you have implemented input and output only from s1 and s2 . So if you write from s1 , it won't go into s2 . In fact you need to create another socket from ss2 that will accept connections. And the same with ss1 . I hope you get my point

Actually you should have created only one ss for the host. Then:

socketHost = ss.accept();

socketClient = new Socket(host, port);

Now you can use these two sockets for communication with each other by using their I/O streams.

In short earlier you had made two connections say a and b . You sent and received from a on one thread and sent and received data from b on the second thread.

Just look up on some tutorial of simple socket I/O and you will understand.

EDIT : See EchoClient.java and EchoServer.java from http://docs.oracle.com/javase/tutorial/networking/sockets/readingWriting.html