Java中使用TCP / IP的服务器-客户端。无法发送/接收消息

Question

因此，我正在制作一个简单的聊天应用程序以启动Java Networking。我正在使用TCP / IP，问题是客户端不从服务器发送/接收数据，服务器也不发送/接收数据。做错了？ 这是我的服务器类：

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;

public class Server implements Runnable {
static InetAddress address;
static ArrayList<Integer> clients=new ArrayList<Integer>();
static ArrayList<Socket> s=new ArrayList<Socket>();
static String message;
static byte[] mess=new byte[2048];
static DataOutputStream toClient;
public Server(InetAddress address){
    this.address=address;

}
public static void main(String[] args) throws IOException
{
    ServerSocket socket=new ServerSocket(8000);
    System.out.println("Server started on port 8000");

    while(true)
    {   
        Socket socketNew=socket.accept();
        s.add(socketNew);
        address=socketNew.getInetAddress();
        System.out.println("connected to client at address: "+address);
        InputStream is=socketNew.getInputStream(); //receiving from client
        InputStreamReader isr=new InputStreamReader(is);
        BufferedReader br=new BufferedReader(isr);
        message=br.readLine();

        Server server=new Server(address);
        //new Thread(server).start();


    }
}


public void run() {

for(Socket socket:s) //to send message to all clients
{
    OutputStream os;
    try {
        os = socket.getOutputStream();
        OutputStreamWriter osw=new OutputStreamWriter(os);
        BufferedWriter bw=new BufferedWriter(osw);
        bw.write(message);
        bw.flush();
        socket.close();

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

}

}

}

这是我的客户端类的发送和接收函数：

    private void send_data() {
    try {
        OutputStream os = socket.getOutputStream();
        OutputStreamWriter osw=new OutputStreamWriter(os);
        BufferedWriter bw=new BufferedWriter(osw);
        String sendMessage=this.getName()+": "+textField.getText();

        bw.write(sendMessage);
        bw.flush();
    } catch (IOException e) {

        e.printStackTrace();
    }


}



private void receive_data()
{

    try {
        InputStream is = socket.getInputStream();
        InputStreamReader isr=new InputStreamReader(is);
        BufferedReader br=new BufferedReader(isr);
        String toConsole=br.readLine();

        console(toConsole);

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


}

Answer 1

我不知道您是如何编写客户端代码来连接Server ，也不知道您是否对ip-configuratoin设置。

通常，通过Socket和ServerSocket编写内容的技巧很少，它是在消息的末尾添加行分隔符，以使另一端能够从套接字readLine() 。

这可以通过在消息后附加\\n来实现。 但是我自己更喜欢使用PrintWriter而不是BufferedWriter ，因为它具有一组优雅的重载println方法，这些方法可以自动为您执行此操作：

PrintWriter p = new PrintWriter(bw);
p.println(message);

希望这会有所帮助。

Answer 2

您的服务器正在等待接收来自客户端的/ n终止消息。

服务器代码：

package general;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;

public class ChatServer implements Runnable {
static InetAddress address;
static ArrayList<Integer> clients=new ArrayList<Integer>();
static ArrayList<Socket> s=new ArrayList<Socket>();
static String message;
static byte[] mess=new byte[2048];
static DataOutputStream toClient;

public ChatServer(InetAddress address){
    this.address=address;
}

public static void main(String[] args) throws IOException
{
    ServerSocket socket=new ServerSocket(9000);
    System.out.println("Server started on port 9000");

    while(true)
    {   
        Socket server=socket.accept();
        s.add(server);
        address=server.getInetAddress();
        System.out.println("connected to client at address: "+address);
        BufferedReader br = new BufferedReader(new InputStreamReader(server.getInputStream()));
        String resp = br.readLine();
        System.out.println("Server received from Client:" + resp);
        server.close();

        /*
        DataInputStream in = new DataInputStream(socketNew.getInputStream());
        System.out.println(in.readUTF());
        DataOutputStream out =
                new DataOutputStream(socketNew.getOutputStream());
        out.writeUTF("Thank you for connecting to "
            + socketNew.getLocalSocketAddress() + "\nGoodbye!");
        */
    }
}


public void run() {

    for(Socket socket:s) //to send message to all clients
    {
        OutputStream os;
        try {
            os = socket.getOutputStream();
            OutputStreamWriter osw=new OutputStreamWriter(os);
            BufferedWriter bw=new BufferedWriter(osw);
            bw.write(message);
            bw.flush();
            socket.close();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

}

客户代码：

public static void main(String[] args) {
    try {
        client=new Socket("127.0.0.1",9000);
        System.out.println("connected to: " + client.getRemoteSocketAddress());
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(client.getOutputStream()));
        String sendingMessage = "Hello Server - This is the client!\n";
        bw.write(sendingMessage);
        bw.flush();

        System.out.println("Message sent to the server : "+ sendingMessage);

        /*
        OutputStream outToServer = client.getOutputStream();
        DataOutputStream out = new DataOutputStream(outToServer);

        out.writeUTF("Hello from \n" + client.getLocalSocketAddress());
        InputStream inFromServer = client.getInputStream();
        DataInputStream in = new DataInputStream(inFromServer);
        System.out.println("Server says " + in.readUTF());
        */
        client.close();         
    } catch (UnknownHostException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

输出：

服务器：服务器在连接到客户端的端口9000上启动，地址为/127.0.0.1从客户端：Hello服务器收到服务器-这是客户端！

客户端：连接到：/127.0.0.1:9000发送到服务器的消息：Hello Server-这是客户端！