java - 简单的 Java IRC 客户端

Question

我正在尝试编写一个非常简单的 IRC 客户端，希望以后能够扩展它。

此时，我有两个用 java 编写的类，它们应该协同工作，并且是从 Oracle 教程中复制的。我想做的是让 EchoClient 连接到某个端口上的主机，以便运行 EchoServer 的主机可以打印出客户端键入的内容。我试图完全按照教程所说的操作，但是在复制并粘贴代码后出现错误。

EchoClient.java:

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

public class EchoClient {
    public static void main(String[] args) throws IOException {
    if (args.length != 2) {
        System.err.println(
            "Usage: java EchoClient <host name> <port number>");
        System.exit(1);
    }

    String hostName = args[0];
    int portNumber = Integer.parseInt(args[1]);

    try (
        Socket echoSocket = new Socket(hostName, portNumber);
        PrintWriter out =
            new PrintWriter(echoSocket.getOutputStream(), true);
        BufferedReader in =
            new BufferedReader(
                new InputStreamReader(echoSocket.getInputStream()));
        BufferedReader stdIn =
            new BufferedReader(
                new InputStreamReader(System.in))
    ) {
        String userInput;
        while ((userInput = stdIn.readLine()) != null) {
            out.println(userInput);
            System.out.println("echo: " + in.readLine());
        }
    } catch (UnknownHostException e) {
        System.err.println("Don't know about host " + hostName);
        System.exit(1);
    } catch (IOException e) {
        System.err.println("Couldn't get I/O for the connection to " +
            hostName);
        System.exit(1);
    }
}

}

EchoServer.java:

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

public class EchoServer {
  public static void main(String[] args) throws IOException {

    if (args.length != 1) {
        System.err.println("Usage: java EchoServer <port number>");
        System.exit(1);
    }

    int portNumber = Integer.parseInt(args[0]);

    try (
        ServerSocket serverSocket =
            new ServerSocket(Integer.parseInt(args[0]));
        Socket clientSocket = serverSocket.accept();
        PrintWriter out =
            new PrintWriter(clientSocket.getOutputStream(), true);
        BufferedReader in = new BufferedReader(
            new InputStreamReader(clientSocket.getInputStream()));
    ) {
        String inputLine;
        while ((inputLine = in.readLine()) != null) {
            out.println(inputLine);
        }
    } catch (IOException e) {
        System.out.println("Exception caught when trying to listen on port "
            + portNumber + " or listening for a connection");
        System.out.println(e.getMessage());
    }
}

}

当我尝试从终端使用 java EchoServer 2000 运行已编译的 EchoServer 时我收到错误，Error: Could not find or load main class EchoClient我从 java EchoServer 2000 得到同样的错误

Answer 1

Echo 服务器示例向您展示了如何执行此操作。首先使用客户端创建的套接字设置某种输出流:

Socket echoSocket = new Socket(hostName, portNumber);
PrintWriter out =
    new PrintWriter(echoSocket.getOutputStream(), true);

然后，当您有消息要发送时，使用 println() 将结果写入 out 对象。

String userInput;
while ((userInput = stdIn.readLine()) != null) {
    out.println(userInput);
    //... 
}

您可以在教程页面的代码列表中找到这些行:https://docs.oracle.com/javase/tutorial/networking/sockets/readingWriting.html

这不是写入套接字的唯一方法，但示例就是这样做的，您现在应该坚持使用它。