java - In & Out 无法解析为类型 (Java Socket)

Question

我真的不知道问题出在哪里。我正在学习 Java，并且正在关注 Oracle 的网络文档。我只是复制并粘贴了他们的示例并得到了这个错误。有人可以帮忙吗？谢谢:)

这是来自 Oracle 的代码:

import java.net.Socket;
import java.net.ServerSocket;

public class EchoServer {

    public static void main(String[] args) throws Exception {

        // create socket
        int port = 4444;
        ServerSocket serverSocket = new ServerSocket(port);
        System.err.println("Started server on port " + port);

        // repeatedly wait for connections, and process
        while (true) {

            // a "blocking" call which waits until a connection is requested
            Socket clientSocket = serverSocket.accept();
            System.err.println("Accepted connection from client");

            // open up IO streams
            In  in  = new In (clientSocket);
            Out out = new Out(clientSocket);

            // waits for data and reads it in until connection dies
            // readLine() blocks until the server receives a new line from client
            String s;
            while ((s = in.readLine()) != null) {
                out.println(s);
            }

            // close IO streams, then socket
            System.err.println("Closing connection with client");
            out.close();
            in.close();
            clientSocket.close();
        }
    }
}

Answer 1

看来你复制错了。

我第一次尝试就能够运行它。

echo: 
hi mom
echo: hi mom
how are you?
echo: how are you?

我拿走了他们所拥有的东西，并对其进行了一些重新混合，以使其更简单(更少的代码，并且它做了同样的事情)。您需要 JDK 7，但您可以将它们放入 IDE 中。首先点击在服务器上运行。然后点击客户端上的运行。然后点击IDE的输出区域，开始在客户端中输入。或者您可以从命令行运行它们。

package com.examples;
import java.net.*;
import java.io.*;

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

    int port;

    if ( args.length != 1 ) {
        System.out.println("listening to port 9999");
        port = 9999;
    } else {
        port = Integer.parseInt ( args[ 0 ] );

    }

    try (
            ServerSocket serverSocket =
                    new ServerSocket(port);
            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);
        }
    }
  }
}

上面使用了新的 JDK 7 try 和自动关闭语法。你要这个。

然后这是重新混合的客户端。

package com.examples;

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

public class EchoClient {
  public static void main ( String... args ) throws IOException {

    String host;
    int port;

    if ( args.length != 2 ) {
        System.out.println("binding to port localhost:9999");
        host = "localhost";
        port = 9999;
    } else {
        host = args[ 0 ];
        port = Integer.parseInt ( args[ 1 ] );
    }

    try (
            Socket echoSocket = new Socket ( host, port );
            PrintWriter out =
                    new PrintWriter ( echoSocket.getOutputStream (), true );
            BufferedReader in =
                    new BufferedReader (
                            new InputStreamReader ( echoSocket.getInputStream () ) );
            BufferedReader stdIn =
                    new BufferedReader (
                            new InputStreamReader ( System.in ) )
    ) {
        System.out.println("Type in some text please.");
        String userInput;
        while ( ( userInput = stdIn.readLine () ) != null ) {
            out.println ( userInput );
            System.out.println ( "echo: " + in.readLine () );
        }
    }
  }
}

服务器如下:

我们从传递给 main 的参数中获取端口号，或者如果它们没有在命令行上传递，则将它们设置为 9999。

    int port;

    if ( args.length != 1 ) {
        System.out.println("listening to port 9999");
        port = 9999;
    } else {
        port = Integer.parseInt ( args[ 0 ] );

    }

然后在 try 语句括号中我们打开服务器套接字 streak gak

            ServerSocket serverSocket =
                    new ServerSocket(port);
            Socket clientSocket = serverSocket.accept();
            PrintWriter out =
                    new PrintWriter(clientSocket.getOutputStream(), true);
            BufferedReader in = new BufferedReader(
                    new InputStreamReader(clientSocket.getInputStream())); 

如果上面的内容没有意义，那么您必须了解有关流的更多信息。转到有关输入/输出(读取和写入文件)的教程，然后返回到此。

基本上，它将服务器套接字的输出流包装在 PrintWriter 中，并将输入流包装在 BufferedReader 中。如果您以前没有使用过 Java I/O API，那么它会有点令人畏惧，所以我建议先从 I/O 教程开始。

原文如下:
EchoClient
EchoServer

根据你搞砸的地方，开始阅读 IO-Streams ，然后 IO-Character Streams .

然后在几个小时的背景知识之后回到这里。