java 套接字输入流

Question

我正在尝试使用客户端登录创建一个简单的客户端-服务器聊天应用程序。我已经上网几天了，正在寻找有关我目前遇到的问题的答案。我已经尝试了所有建议和“解决方案”，但仍然无法正常运行。

问题在于流。如果我在向服务器发送字符串后关闭客户端输出流，则服务器成功读取字符串。但是随后服务器无法发回响应，因为套接字已关闭。如果我不关闭客户端输出流，服务器将无法读取客户端发送的任何数据。我试过摆弄我的代码，但无济于事。

这是我的客户端代码：

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

public class Client {

public static BufferedReader bf;
public static PrintWriter pw;
public static Socket s;
public static ClientLogin login = new ClientLogin();
public String me;

public static boolean connect(String ip, int port){
    try {
        s = new Socket(ip, port);
        pw = new PrintWriter(s.getOutputStream(), true);
        bf = new BufferedReader(new InputStreamReader(s.getInputStream()));
        new ServerListener().start();

    }catch (ConnectException ce){
        return false;
    } catch (UnknownHostException ex) {
        return false;
    } catch (IOException ex) {
        return false;
    }
    return true;
}

public void send(String msg){
    try{
        if(msg.length()>0){
            pw.write(msg);
            System.out.println("client message sent.. " + msg);
        }
    }catch(Exception e){
        System.out.println("Error in client sender: " + e);
    }
}
}

class ServerListener extends Thread{

@Override
public void run(){

    String res = "";
    String input;
    try{
        System.out.println("client listening....");
        input = Client.bf.readLine();
        System.out.println(input);

        if(input.startsWith("LOGIN")){
            ClientLogin cl = new ClientLogin();
            cl.login(input);
        }else{
            ClientLogin.errorLabel.setText(input);
        }

    }catch(Exception e){ 
        System.out.println("Error in Client listener: " + e); e.printStackTrace();
    }

}

}

服务器代码：

package server;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.Socket;
import java.net.ServerSocket;
import java.net.SocketException;
import java.util.LinkedList;

public class ChatServer {
    public static final LinkedList<Socket> sockets = new LinkedList<>();
    private static Dbdriver db;
    private static int users;
    static clientThread cl = new clientThread();
    public static InetAddress ia;

public ChatServer(){
    db = new Dbdriver(); //database connection
    db.getClass();
    try{
        users = db.countUsers();
    }catch(Exception e){ e.printStackTrace(); }
}

//START SERVER
public static void startServer(){
    clientThread s = new clientThread();
    s.start();
}

public static void stopServer(){
    try {
        synchronized(ChatServer.sockets){
            for(Socket ss:sockets){
                if(ss.isConnected()){
                    MessengerEngine.pw.close();
                    ss.close();
                }
            }
            sockets.clear();
        }
        cl.theServer.close();
    } catch (IOException ex) {ex.printStackTrace(); }
}

}

class clientThread extends Thread {

public static ServerSocket theServer;

@Override
public void run() {
    int port = 8888;
    try{
        theServer = new ServerSocket(port);

        while(true){
            MessengerEngine engine = new MessengerEngine(theServer.accept());
            engine.start();         
        }
    }catch(SocketException se){
    }catch(Exception e){ 
    }
}
}

class MessengerEngine extends Thread{

public static Dbdriver theDriver;
private Socket theSocket;
    private BufferedReader bf;
    private PrintWriter pw;

    public String ipadd;

public MessengerEngine(Socket s){
    theSocket = s;
    synchronized(ChatServer.sockets){
        ChatServer.sockets.add(theSocket);
    }

try{
        bf = new BufferedReader(new InputStreamReader(theSocket.getInputStream()));
        pw = new PrintWriter(theSocket.getOutputStream(), true);
        ipadd = s.getInetAddress().getHostAddress();
        AdminServer.serverLog.setText(AdminServer.serverLog.getText() + ipadd +" has connected." +"\n");
}catch(Exception e){
        System.out.println("Socket.accept error");
}
}

@Override
public void run(){

    String res = ""; //server response

        try{
            String input = bf.readLine();
            System.out.println("String from client: " + input);
            String[] inputs= input.split("-");

            if(input.startsWith("LOGIN")){ //LOGIN - "LOGIN-name-pass-ip"
                Dbdriver db = new Dbdriver();
                res = db.userLogin(inputs[1], inputs[2], inputs[3]);
                System.out.println("Client logging in sent: " + inputs[1] + ", " + inputs[2] +", " + inputs[3]);
                send(res);
            }
        }catch(IOException e){
            e.printStackTrace(); 
        }
}

public void send(String msg){
    System.out.println("Server trying to send: "+ msg);
    pw.write(msg);
    System.out.println("server sent message..");
}
} 

来自客户端的所有数据都来自文本字段（用户名、密码）。我希望服务器通过从数据库中检查来验证客户端登录。从文本字段收集并验证登录效果很好。我唯一的问题是客户端输入流..我想。帮助一个菜鸟编程学生？请。

服务器抛出异常：

java.net.SocketException: Connection reset
at java.net.SocketInputStream.read(SocketInputStream.java:196)
at java.net.SocketInputStream.read(SocketInputStream.java:122)
at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:283)
at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:325)
at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:177)
at java.io.InputStreamReader.read(InputStreamReader.java:184)
at java.io.BufferedReader.fill(BufferedReader.java:154)
at java.io.BufferedReader.readLine(BufferedReader.java:317)
at java.io.BufferedReader.readLine(BufferedReader.java:382)
at server.MessengerEngine.run(ChatServer.java:102)

ChatServer.java:102 >> 字符串输入 = bf.readLine();

Answer 1

在通信完成之前，您不得关闭流。它也总是会导致关闭套接字。您需要做的是在向数据输出流写入内容后使用dos.flush()，以使服务器在您完成通信后才能获取信息并关闭dos。