Java套接字輸入流

Question

我試圖創建一個簡單的客戶端 - 服務器的聊天應用與客戶端登錄。 我已經在網上呆了幾天，現在正在尋找有關我當前遇到的問題的答案。 我已經嘗試了所有建議和“解決方案”，但仍然無法正常運行。

問題出在流上。 如果在將字符串發送到服務器后關閉客戶端輸出流，則服務器將成功讀取該字符串。 但后來因為套接字已被關閉，服務器無法發送回一個響應。 如果我不關閉客戶端輸出流，則服務器無法讀取客戶端發送的任何數據。 我試着擺弄我的代碼，但無濟於事。

這是我的客戶代碼：

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();
    }

}

}

服務器代碼：

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..");
}
} 

來自客戶端的所有數據均來自文本字段（用戶名，密碼）。 我希望服務器通過從數據庫中檢查來驗證客戶端登錄。 從文本字段中收集並驗證登錄是否完美。 我唯一的問題是客戶輸入流。 幫助菜鳥編程的學生嗎？ 請。

服務器引發的異常：

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 >>字符串輸入= bf.readLine（）;

Answer 1

在完成通信之前，您不得關閉流。 總是也會導致關閉插座。 您需要做的是在向數據輸出流中寫入內容之后使用dos.flush() ，以使服務器能夠獲取信息並僅在完成通信后關閉dos。