import java.net.URL;import java.net.URLConnection;import java.io.InputStreamReader;import java.io.BufferedReader;import java.net.HttpURLConnection;/**客户端仅仅是获取服务端的信息*/public class HttpClient{ ???private String urlString; ???public static void main(String[] args) throws Exception{ ???????if(args.length!=1){ ???????????System.out.println("控制台参数错误！"); ???????????//终止当前运行的Java虚拟机。 ???????????System.exit(1); ???????????} ???????HttpClient client = new HttpClient(args[0]); ???????client.run(); ???????} ???????public HttpClient(String url){ ???????this.urlString = url; ???????} ???????????private void run() throws Exception{ ???????URL url = new URL(this.urlString); ???????URLConnection conn = url.openConnection(); ???????if(conn instanceof HttpURLConnection){ ???????????HttpURLConnection httpConn = (HttpURLConnection)conn; ???????????String key; ???????????String value; ???????????System.out.println("The Headers"); ???????????System.out.println("========================================="); ???????????for(int i=1;;i++){ ???????????????if((key=httpConn.getHeaderFieldKey(i))==null){ ???????????????????break; ???????????????????} ???????????????if((value=httpConn.getHeaderField(i))==null){ ???????????????????break; ???????????????????} ???????????????System.out.println("key["+key+"]"); ???????????????System.out.println("value["+value+"]"); ???????????????????} ???????????BufferedReader reader = new BufferedReader(new InputStreamReader(httpConn.getInputStream())); ???????????String line; ???????????System.out.println("Content"); ???????????System.out.println("========================================="); ???????????while((line=reader.readLine())!=null){ ???????????????System.out.println(line); ???????????????} ???????????} ???}} ???执行结果：G:\maul keyboard\network programming>java HttpClient http://www.google.cnThe Headers=========================================key[Accept-Ranges]value[none]key[Vary]value[Accept-Encoding]key[Content-Type]value[text/html]key[Date]value[Sat, 10 Nov 2018 10:56:42 GMT]key[Expires]value[Sat, 10 Nov 2018 10:56:42 GMT]key[Cache-Control]value[private, max-age=0]key[Last-Modified]value[Thu, 08 Dec 2016 01:00:57 GMT]key[X-Content-Type-Options]value[nosniff]key[Server]value[sffe]key[X-XSS-Protection]value[1; mode=block]key[Transfer-Encoding]value[chunked]Content=========================================<!DOCTYPE html><html lang="zh"> ?<meta charset="utf-8"> ?<title>Google</title> ?<style> ???html { background: #fff; margin: 0 1em; } ???body { font: .8125em/1.5 arial, sans-serif; text-align: center; } ???h1 { font-size: 1.5em; font-weight: normal; margin: 1em 0 0; } ???p#footer { color: #767676; font-size: .77em; } ???p#footer a { background: url(//www.google.cn/intl/zh-CN_cn/images/cn_icp.gif) top right no-repeat; padding: 5px 20px 5px 0; }...HTTP客户端
原文地址：https://www.cnblogs.com/celine/p/9940270.html