java - 基本 Java 套接字，服务器不能发送，客户端也不能接收任何东西

Question

我根据“java-all-in-one desk reference for Dummies”一书中的教程用 Java 编写了一个基本的客户端-服务器套接字程序，它包含 3 个类，BartServer、BartClient、BartQuote.. 基本上是什么BartServer.class 的作用是监听 BartClient.class，BartClient 在执行时会向 BartServer 发送命令，BartServer 根据 BartClient 发送的内容进行回复。

如果是“get”命令，BartServer 将回复从 BartQuote.class 生成的随机报价else of "bye"将退出客户端...我在本地主机上尝试过，客户端成功连接了服务器，但是 BartServer 没有做任何事情，客户端也不会收到...命令无法响应或任何...我哪里出错了？抱歉我的英语不好...

BartServer:

package socketBart;
import java.net.*;import java.io.*;import java.util.*;

public class BartServer {

public static void main(String[] args)
{
    int port = 1892;

    BartQuote bart = new BartQuote();

    try
    {
        System.out.println("BartServer 1.0");
        System.out.println("Listening on port "+port);
        ServerSocket ss = new ServerSocket(port);
        Socket s = ss.accept(); // WAITS for a client to connect, once connected, returns a socket object
        // once clients connects and socket s is created, it will proceed to the next line

        String client;
        client = s.getInetAddress().toString();
        System.out.println("Connected to "+ client);

        Scanner in = new Scanner(s.getInputStream()); //READS data sent to this server from CLIENTS
        PrintWriter out = new PrintWriter(s.getOutputStream()); //SENDS data FROM this server to CLIENTS

        out.println("Welcome to BartServer 1.0");// these lines are sent to the client
        out.println("Enter GET to get a quote or BYE to exit.");

        while (true)
        {
            String input = in.nextLine();
            if (input.equalsIgnoreCase("bye"))
                break;
            else if (input.equalsIgnoreCase("get"))
            {
                out.println(bart.getQuote());
                System.out.println("Serving "+ client);
            }
            else
                out.println("Huh?");
        }
        out.println("So long suckers!");
        s.close();

        System.out.println("Closed connection to " + client);
    }
    catch(Exception e){
        e.printStackTrace();
    }

}

}

巴特客户端:

package socketBart;
import java.net.*;import java.util.*;import java.io.*;

public class BartClient {

public static void main(String[] args)
{
    int port = 1892;
    System.out.println("Welcome to the Bart Client\n");
    Socket s = getSocket(port);

    try
    {
        System.out.println("Connected on port " + port);

        Scanner in = new Scanner(s.getInputStream());
        PrintWriter out = new PrintWriter(s.getOutputStream(),true);

        //discard welcome message from server
        in.nextLine();

        //discard the exit instructions
        in.nextLine();

        //get a quote
        out.println("get");
        String quote = in.nextLine();

        //disconnect from server
        out.println("bye");
        s.close();

        //write the quote of the 'chalkboard'
        for (int i = 0; i < 20; i++)
            System.out.println(quote);
    }
    catch (Exception e)
    {
        e.printStackTrace();
    }

}

private static Socket getSocket(int port)
{
    Socket s;
    String host;
    InetAddress ip;

    Scanner sc = new Scanner(System.in);
    while (true)
    {
        System.out.print("Connect to server: ");
        host = sc.nextLine();

        try
        {
            ip = InetAddress.getByName(host);
            s = new Socket(ip,port);
            return s;
        }
        catch(UnknownHostException e)
        {
            System.out.println("The host is unknown.");
        }
        catch (IOException e)
        {
            System.out.println("Network error, check your port.");
        }//end catch
    }
}

}

巴特引用:

package socketBart;
import java.util.Random;
import java.util.ArrayList;

public class BartQuote {

ArrayList<String> q = new ArrayList<String>();

public BartQuote()
{
    q.add("I will not waste chalk");
    q.add("I will not skateboard in the halls");
    q.add("I will not burp in the class");
    q.add("I will not instigate a revolution");
    q.add("It's potato, not potatoe.");
    q.add("I will not encourage others to fly.");
    q.add("Tar is not a plaything.");
    q.add("I will not sell school property.");
    q.add("I will not get very far with this attitude");
    q.add("I will not sell land in Florida.");
    q.add("I will not grease the monkey bars.");
    q.add("I am not a dentist");
    q.add("I will finish what I started.");
    q.add("Hamsters cannot fly");
}

public String getQuote()
{
    int i = new Random().nextInt(q.size());
    return q.get(i);
}



}

Answer 1

更改服务器上的这一行:

PrintWriter out = new PrintWriter(s.getOutputStream());

到:

PrintWriter out = new PrintWriter(s.getOutputStream(), true);

这将改变，以便服务器始终在写入后刷新流。否则，数据可能会在输出流的服务器缓冲区中徘徊。

请注意，您的客户端代码已设置为自动刷新。