Socket readLine() doesn't receive line sent

问题

I'm building a client-server project.
What I need is that the client sends a string, such as "Pendu", and the server receives this string and send an object named "Pendu" back to the client.

Here is my code:

// server
ServerSocket serverSocket = new ServerSocket(6789);
System.out.println("accepting...");
Socket socket = serverSocket.accept();
BufferedReader inFromClient = new BufferedReader(new InputStreamReader(socket.getInputStream()));
ObjectOutputStream outToClient = new ObjectOutputStream(socket.getOutputStream());
String clientMsg = inFromClient.readLine();
System.out.println("Received from client: " + clientMsg);
Object obj;
System.out.println("building object...");
obj = Class.forName("Data." + clientMsg).newInstance();
System.out.println("object built");
if(obj instanceof Pendu)
{
    System.out.println("Send to client: " + obj);
    outToClient.writeObject(new Pendu());
}

//client
Socket socket = new Socket("localhost", 6789);
DataOutputStream outToServer = new DataOutputStream(socket.getOutputStream());
System.out.println("sending...");
outToServer.writeBytes("Pendu");
System.out.println("sent");
ObjectInputStream ois = new ObjectInputStream(socket.getInputStream());
System.out.println("receiving...");
Object obj = ois.readObject(); // it is blocked here and I don't know why
System.out.println("received");

The class Pendu is defined in the package Data:

package Data;

public class Pendu implements Serializable
{
    private static final long serialVersionUID = 1L;
    private static String[] words = new String[]{"bonjour", "bonsoir", "hier", "france", "ordinateur"};
    private static Random rand = new Random();
    private String but;

    public Pendu()
    {
        this.but = words[rand.nextInt(words.length)];
    }

    public int getLenth()
    {
        return this.but.length();
    }

    public String getBut()
    {
        return this.but;
    }

    @Override
    public String toString()
    {
        return "I'm a pendu object";
    }
}

My problem is:
First I execute the server and I can see that accepting... is shown in the console.
Then I execute the client, in the console I get messages as below:

sending...
sent
receiving...

At the same time, nothing new is shown at the server side.
Now I stop the client and all other messages of the server are shown:

Received from client: Pendu
building object...
object built

Of course I get also the error:

java.net.SocketException: Broken pipe

This is logical because I kill the client which hasn't finish receiving.
I don't know why the client can't receive as expected.

回答1:

You are reading lines but not writing lines. You need to add a line terminator to the "Pendu" message.

NB When you send a Pendu, why are you sending a new one instead of the one you just created?

来源：https://stackoverflow.com/questions/42881425/socket-readline-doesnt-receive-line-sent

标签

java

sockets

serialization