Java套接字连接接收和发送String和Object

Question

I've created a client, a server and an object called CcyData . When the client connects to the server I would like the server the send a "Welcome message" like "Hello, you are client# " + clientNumber . as a String and then send an object CcyData . I've managed to get the sending of the CcyData object to work but when I try to read in the "Welcome message" with

input = new BufferedReader(new InputStreamReader(socket.getInputStream()));
System.out.println("Welcome message from server: "+ input.readLine());

the client stops working, nothing happens. No error message. Below is my code. How can I solve this?

Server.

package net.something;

import java.io.IOException;
import java.net.ServerSocket;


public class SocketServer {

private ServerSocket serverSocket = null;
private int clientNumber = 0;

public SocketServer() {
}

public void listenSocket () {
    int clientNumber = 0;

    try{
        serverSocket = new ServerSocket(9090);
        System.out.println("Server started on port 9090");
    } catch(IOException e) {
        e.printStackTrace();
    }

    while (true) {
        ClientSocket clientSocket;
        try{
            clientSocket = new ClientSocket(serverSocket.accept(), serverSocket, clientNumber++);
            Thread thread = new Thread(clientSocket);
            thread.start();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}
}

Class ClientSocket

package net.something;

import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

public class ClientSocket implements Runnable {
private Socket clientSocket;
private ServerSocket serverSocket;
private int clientNumber;

public ClientSocket(Socket clientSocket, ServerSocket serverSocket, int clientNumber) {
    this.clientSocket = clientSocket;
    this.serverSocket = serverSocket;
    this.clientNumber = clientNumber;
    System.out.println("New connection with client# " + clientNumber + " at " + clientSocket);
    }

public void run() {

    PrintWriter out;
    ObjectOutputStream outObjectStream;

    try {
        out = new PrintWriter(clientSocket.getOutputStream());
        out.println("Hello, you are client# " + clientNumber);
        outObjectStream = new ObjectOutputStream(clientSocket.getOutputStream());
        CcyData ccyData = new CcyData("EUR", 9.56);
        System.out.println("CcyData: " + ccyData.getCcy() + " " + ccyData.getFxRate());
        outObjectStream.writeObject(ccyData);
    } catch (IOException e) {
        e.printStackTrace();
    }
}

public void finalize() {
    try{
        serverSocket.close();
        System.out.println("Server socket closed");
    } catch (IOException e) {
        e.printStackTrace();
    }
}
}

Client

package net.something;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.ObjectInputStream;
import java.net.Socket;

public class SocketClient {

private Socket socket = null;
private BufferedReader input;
private ObjectInputStream inObjectStream = null;

public SocketClient() {
}

public void connectToServer() {

    try{
        socket = new Socket("127.0.0.1", 9090);
        input = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        System.out.println("Welcome message from server: "+ input.readLine());
        inObjectStream = new ObjectInputStream(socket.getInputStream());
        CcyData ccyData = (CcyData) inObjectStream.readObject();
        System.out.println(ccyData.getCcy() + " " + ccyData.getFxRate());
    } catch (IOException | ClassNotFoundException e) {
        e.printStackTrace();
    }

}
}

Answer 1

finalize is only called when the JVM garbage collector decides that there are no more references to your thread and disposes it. Thus, you cannot ensure that finalize will be called when your thread has reached the end of its run() method. Try closing the socket in the run method instead!