Question

我想使用套接字访问任意网页（作为我自己的学习机制）。下面的代码不起作用，我做错了什么？

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

public class Example
{
     public static void main(String args[]) throws Exception
     {
          Socket socket =
               new Socket("www.google.com", 80);
          PrintWriter out =
               new PrintWriter(socket.getOutputStream(), true);
          BufferedReader reader =
               new BufferedReader(
                    new InputStreamReader(socket.getInputStream()));

          BufferedReader stdIn =
               new BufferedReader(
                    new InputStreamReader(System.in));

          String userInput;
          while ((userInput = stdIn.readLine()) != null) {
               out.println("GET / HTTP/1.1 \\r\\n Host: www.google.com \\r\\n\\r\\n");
               System.out.println("echo: " + reader.readLine());
         }
     }
}

在尝试了几个小时之后，我无法弄清楚究竟是我做错了什么。我想要的只是谷歌或其他一些网站的主页。任何人都可以帮助我吗？

Answer 1

您可以尝试以下内容（使用套接字）

package com.example.webpagesocket;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.UnknownHostException;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.channels.SocketChannel;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CharsetEncoder;

public class GetWebPageUsingSockets {

    public static void main(String[] args) {
        String urlString;

        urlString = "www.google.com";

        accessWeb(urlString);
    }

    private static void accessWeb(String urlString) {
        String host;
        String page;
        int slashLoc;

        // Set up encoding and decoding
        Charset charset = Charset.forName("ISO-8859-1");
        CharsetDecoder decoder = charset.newDecoder();
        CharsetEncoder encoder = charset.newEncoder();

        if ((slashLoc = urlString.indexOf('/')) < 0) {
            host = urlString;
            page = "";
        } else {
            host = urlString.substring(0, slashLoc);
            page = urlString.substring(slashLoc);
        }

        System.out.println("Accessing web page demonstration");
        System.out.println("Host: '" + host + "' Page: '" + page + "'");

        SocketChannel channel = null;

        try {
            ByteBuffer buffer = ByteBuffer.allocateDirect(1024);
            CharBuffer charBuffer = CharBuffer.allocate(1024);

            InetSocketAddress socketAddress = new InetSocketAddress(host, 80);
            channel = SocketChannel.open();
            channel.connect(socketAddress);

            String request = "GET " + page + " \r\n\r\n";
            channel.write(encoder.encode(CharBuffer.wrap(request)));

            while ((channel.read(buffer)) != -1) {
                buffer.flip();
                decoder.decode(buffer, charBuffer, false);
                charBuffer.flip();
                System.out.println(charBuffer);
                buffer.clear();
                charBuffer.clear();
            }
        } catch (UnknownHostException e) {
            System.err.println(e);
        } catch (IOException e) {
            System.err.println(e);
        } finally {
            if (channel != null) {
                try {
                    channel.close();
                } catch (IOException ignored) {
                }
            }
        }

        System.out.println("\nDone.");
    }
}

Answer 2

编辑：在第一次阅读时没有注意到......

看起来您不断向主机发送"GET / HTTP/1.1 \\r\\n Host: www.google.com \\r\\n\\r\\n"（每次阅读时）。您最好将其保持在循环之外并发送真carriage return + line feed而不是可打印的字符\ r \ n：

  out.println("GET / HTTP/1.1 \r\nHost: www.google.com\r\n\r\n");
  String userInput;
      while ((userInput = stdIn.readLine()) != null) {

您只能在发送GET后开始阅读，但套接字将缓冲数据。

错误的请求和超时

2 个答案: