早就有想写一个Java Socket编程系列的文章，由于自己懒一直没动。决定从
今天开始，每周写一篇，从最简单的socket连接，到文件传输到协议实现，到
远程桌面控制，全面讲述Java socket编程的各个方面与各种技巧，从普通
socket到Java NIO。
本文算是第一篇，简述如何通过Java Socket获取网站的主页内容其中包括
如何获取本地机器名与IP地址，如何建立一个socket连接到远程WEB站点
如何使用HTTP GET方法获取网站主页内容与HTTP响应头。程序运行结果：
从中我们可以知道csdn网站是基于什么语言开发，服务器是什么，版本是多少。
具体的做法请看源代码：
package com.gloomyfish.socket.tutorial.one; import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.IOException; import java.io.InputStreamReader; import java.io.OutputStreamWriter; import java.net.InetAddress; import java.net.InetSocketAddress; import java.net.Socket; import java.net.SocketAddress; import java.net.UnknownHostException; public class HomePageVisitor { private Socket client; private SocketAddress address; public HomePageVisitor(String hostName, int port) throws UnknownHostException, IOException { client = new Socket(); address = new InetSocketAddress(hostName, port); } // GET http://localhost:8080/blank/Welcome.do HTTP/1.1\r\n public void printHomePageInfo(String httpString) { try { // Get local host info InetAddress inetAddress = InetAddress.getLocalHost(); System.out.println("Host Address = " + inetAddress.getHostAddress()); System.out.println("Hostname = " + inetAddress.getHostName()); // visit the WEBSITE client.connect(address); BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(client.getOutputStream(), "UTF8")); bufferedWriter.write(httpString); // -- HTTP/1.1 400 Bad Request if not send \r\n bufferedWriter.write("\r\n"); bufferedWriter.flush(); System.out.println("http request send out"); BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(client.getInputStream())); String content = null; while((content = bufferedReader.readLine()) != null) { if(getStatusCde(content) == 400) { System.err.println("HTTP/1.1 | HTTP/1.0 400 Bad Request"); break; } System.out.println("response contect -->> " + content); } } catch(Exception e) { e.printStackTrace(); } } /** * <p> try to parse the HTTP response content</p> * @param content * @return status of HTTP */ private static int getStatusCde(String content) { int status = 200; // default OK response if(content == null || "".equals(content)) return status; else if (!content.contains("HTTP/1.1")&& !content.contains("HTTP/1.0")) return status; else if(content.contains("400") && content.contains("HTTP/1.1") || content.contains("HTTP/1.0")) { status = 400; } return status; } public static void main(String[] args) { try { HomePageVisitor httpVisitor = new HomePageVisitor("www.csdn.net", 80); httpVisitor.printHomePageInfo("GET http://www.csdn.net HTTP/1.0\r\n"); } catch (UnknownHostException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } }
如果使用了代理，在初始化Address时候使用HTTP代理的地址与端口
接口，其它不变，代理会自动转发HTTP GET请求。代码如下：
address = new InetSocketAddress(http_proxy, proxy_port)
