Java Socket/HttpURLConnection读取HTTP网页

约定不等于承诺〃 2023-10-18 15:12 3阅读 0赞

以读取百度的http网页为例。如果知道了IP地址和端口，然后新建一个Socket，就直接去读百度的首页，根本没反应，原因是www.baidu.com是以http协议传输的，而现在要以Socket原始的套接字读写，远程服务器没有收到客户端的GET报文，故无法做出响应。正确的方式是在Socket输出流中写入HTTP的GET报文，输出流中的报文告诉远程服务器自己要GET网页内容，这样远程服务器才会响应我们的数据请求：

import java.io.BufferedInputStream;
    import java.io.BufferedWriter;
    import java.io.OutputStreamWriter;
    import java.net.InetAddress;
    import java.net.Socket;
    
    public class Test {
    	public static void main(String[] args) {
    		try {
    			Test test = new Test();
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    	}
    
    	public Test() throws Exception {
    		InetAddress inetAddress = InetAddress.getByName("www.baidu.com");
    		Socket socket = new Socket(inetAddress.getHostAddress(), 80);
    
    		if (socket.isConnected()) {
    			System.out.println("连接建立,远程地址:" + socket.getRemoteSocketAddress());
    		}
    
    		// 关键！此处在Socket的输出流写入HTTP的GET报文，请服务器做出响应。
    		BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
    		bw.write("GET / HTTP/1.1\r\n");
    		bw.write("Host: www.baidu.com\r\n");
    		bw.write("\r\n");
    		bw.flush();
    
    		// 开始读取远程服务器的响应数据。
    		BufferedInputStream bis = new BufferedInputStream(socket.getInputStream());
    
    		byte[] buffer = new byte[1024];
    		int count = 0;
    		while (true) {
    			count = bis.read(buffer);
    			if (count == -1) {
    				break;
    			}
    
    			System.out.println(new String(buffer, 0, count, "UTF-8"));
    		}
    
    		bw.close();
    		bis.close();
    		socket.close();
    	}
    }

代码运行后读出的百度远程服务器响应数据：

连接建立,远程地址:/180.97.33.108:80
    HTTP/1.1 200 OK
    Accept-Ranges: bytes
    Cache-Control: no-cache
    Connection: Keep-Alive
    Content-Length: 14615
    Content-Type: text/html
    Date: Tue, 05 Mar 2019 09:24:38 GMT
    Etag: "5c73a860-3917"
    Last-Modified: Mon, 25 Feb 2019 08:33:36 GMT
    P3p: CP=" OTI DSP COR IVA OUR IND COM "
    Pragma: no-cache
    Server: BWS/1.1
    Set-Cookie: BAIDUID=A4AD1A6D67DD43C32BFF6502C37F4E67:FG=1; expires=Thu, 31-Dec-37 23:55:55 GMT; max-age=2147483647; path=/; domain=.baidu.com
    Set-Cookie: BIDUPSID=A4AD1A6D67DD43C32BFF6502C37F4E67; expires=Thu, 31-Dec-37 23:55:55 GMT; max-age=2147483647; path=/; domain=.baidu.com
    Set-Cookie: PSTM=1551777878; expires=Thu, 31-Dec-37 23:55:55 GMT; max-age=2147483647; path=/; domain=.baidu.com
    Vary: Accept-Encoding
    X-Ua-Compatible: IE=Edge,chrome=1
    
    <!DOCTYPE html>
    <html>
    <head>
    	<meta http-equiv="content-type" content="text/html;charset=utf-8">
    	<meta http-equiv="X-UA-Compatible" content="IE=Edge">
    	<link rel="dns-prefetch" href="//s1.bdstatic.com"/>
    	<link rel="dns-prefetc
    h" href="//t1.baidu.com"/>
    	<link rel="dns-prefetch" href="//t2.baidu.com"/>
    	<link rel="dns-prefetch" href="//t3.baidu.com"/>
    	<link rel="dns-prefetch" href="//t10.baidu.com"/>
    	<link rel="dns-prefetch" href="//t11.baidu.com"/>
    	<link rel="dns-prefetch" href="//t12.baidu.com"/>
    	<link rel="dns-prefetch" href="//b1.bdstatic.com"/>
    	<title>百度一下，你就知道</title>
    	<link href="http://s1.bdstatic.com/r/www/cache/static/home/css/index.css" rel="stylesheet" type="text/css" />
    	
    	
    	<script>var hashMatch = document.location.href.match(/#+(.*wd=[^&].+)/);if (hashMatch && hashMatch[0] && hashMatch[1]) {document.location.replace("http://"+location.host+"/s?"+hashMatch[1]);}var ns_c = function(){};</script>
    	<script>function h(obj){obj.style.behavior='url(#default#homepage)';var a = obj.setHomePa
    ge('//www.baidu.com/');}</script>
    	<noscript><meta http-equiv="refresh" content="0; url=/baidu.html?from=noscript"/></noscript>
    	<script>window._ASYNC_START=new Date().getTime();</script>
    </head>
    <body link="#0000cc"><div id="wrapper" style="display:none;"><div id="u"><a href="//www.baidu.com/gaoji/preferences.html"  onmousedown="return user_c({'fm':'set','tab':'setting','login':'0'})">搜索设置</a>|<a id="btop" href="/"  onmousedown="return user_c({'fm':'set','tab':'index','login':'0'})">百度首页</a>|<a id="lb" href="https://passport.baidu.com/v2/?login&tpl=mn&u=http%3A%2F%2Fwww.baidu.com%2F" onclick="return false;"  onmousedown="return user_c({'fm':'set','tab':'login'})">登录</a><a href="https://passport.baidu.com/v2/?reg&regType=1&tpl=mn&u=http%3A%2F%2Fwww.baidu.com%2F"  onmousedown="return user_c({'fm':'set','tab':'reg'})" target="_blank" class="reg">注册</a></div><div id="head"><div class="s_nav"><a href="/" class="s_logo" onmousedown="return c({'fm':'tab','tab':'logo'})"><img src="//www.b
    aidu.com/img/baidu_jgylogo3.gif" width="117" height="38" border="0" alt="到百度首页" title="到百度首页"></a><div class="s_tab" id="s_tab"><a href="http://news.baidu.com/ns?cl=2&rn=20&tn=news&word=" wdfield="word"  onmousedown="return c({'fm':'tab','tab':'news'})">新闻</a>　<b>网页</b>　<a href="http://tieba.baidu.com/f?kw=&fr=wwwt" wdfield="kw"  onmousedown="return c({'fm':'tab','tab':'tieba'})">贴吧</a>　<a href="http://zhidao.baidu.com/q?ct=17&pn=0&tn=ikaslist&rn=10&word=&fr=wwwt" wdfield="word"  onmousedown="return c({'fm':'tab','tab':'zhidao'})">知道</a>　<a href="http://music.baidu.com/search?fr=ps&key=" wdfield="key"  onmousedown="return c({'fm':'tab','tab':'music'})">音乐</a>　<a href="http://image.baidu.com/i?tn=baiduimage&ps=1&ct=201326592&lm=-1&cl=2&nc=1&word=" wdfield="word"  onmousedown="return c({'fm':'tab','tab':'pic'})">图片</a>　<a href="http://v.baidu.com/v?ct=301989888&rn=20&pn=0&db=0&s=25&word=" wdfield="word"   onmousedown="return c
    ({'fm':'tab','tab':'video'})">视频</a>　<a href="http://map.baidu.com/m?word=&fr=ps01000" wdfield="word"  onmousedown="return c({'fm':'tab','tab':'map'})">地图</a>　<a href="http://wenku.baidu.com/search?word=&lm=0&od=0" wdfield="word"  onmousedown="return c({'fm':'tab','tab':'wenku'})">文库</a>　<a href="//www.baidu.com/more/"  onmousedown="return c({'fm':'tab','tab':'more'})">更多?</a></div></div><form id="form" name="f" action="/s" class="fm" ><input type="hidden" name="ie" value="utf-8"><input type="hidden" name="f" value="8"><input type="hidden" name="rsv_bp" value="1"><span class="bg s_ipt_wr"><input name="wd" id="kw" class="s_ipt" value="" maxlength="100"></span><span class="bg s_btn_wr"><input type="submit" id="su" value="百度一下" class="bg s_btn" onmousedown="this.className='bg s_btn s_btn_h'" onmouseout="this.className='bg s_btn'"></span><span class="tools"><span id="mHolder"><div id="mCon"><span>输入法</span></div><ul id="mMenu"><li><a href="javascript:;" name="im
    e_hw">手写</a></li><li><a href="javascript:;" name="ime_py">拼音</a></li><li class="ln"></li><li><a href="javascript:;" name="ime_cl">关闭</a></li></ul></span><span class="shouji"><strong>推荐 : </strong><a href="http://w.x.baidu.com/go/mini/8/10000020" onmousedown="return ns_c({'fm':'behs','tab':'bdbrowser'})">百度浏览器，打开网页快2秒！</a></span></span></form></div><div id="content"><div id="u1"><a href="http://news.baidu.com" name="tj_trnews" class="mnav">新闻</a><a href="http://www.hao123.com" name="tj_trhao123" class="mnav">hao123</a><a href="http://map.baidu.com" name="tj_trmap" class="mnav">地图</a><a href="http://v.baidu.com" name="tj_trvideo" class="mnav">视频</a><a href="http://tieba.baidu.com" name="tj_trtieba" class="mnav">贴吧</a><a href="https://passport.baidu.com/v2/?login&tpl=mn&u=http%3A%2F%2Fwww.baidu.com%2F" name="tj_login" id="lb" onclick="return false;">登录</a><a href="//www.baidu.com/gaoji/preferences.html" name="tj_settingicon" id="pf">设置</
    a><a href="//www.baidu.com/more/" name="tj_briicon" id="bri">更多产品</a></div><div id="m"><p id="lg"><img src="//www.baidu.com/img/bd_logo.png" width="270" height="129"></p><p id="nv"><a href="http://news.baidu.com">新 闻</a>　<b>网 页</b>　<a href="http://tieba.baidu.com">贴 吧</a>　<a href="http://zhidao.baidu.com">知 道</a>　<a href="http://music.baidu.com">音 乐</a>　<a href="http://image.baidu.com">图 片</a>　<a href="http://v.baidu.com">视 频</a>　<a href="http://map.baidu.com">地 图</a></p><div id="fm"><form id="form1" name="f1" action="/s" class="fm"><span class="bg s_ipt_wr"><input type="text" name="wd" id="kw1" maxlength="100" class="s_ipt"></span><input type="hidden" name="rsv_bp" value="0"><input type=hidden name=ch value=""><input type=hidden name=tn value="baidu"><input type=hidden name=bar value=""><input type="hidden" name="rsv_spt" value="3"><input type="hidden" name="ie" value="utf-8"><span class="bg s_btn_wr"><input type="s
    ubmit" value="百度一下" id="su1" class="bg s_btn" onmousedown="this.className='bg s_btn s_btn_h'" onmouseout="this.className='bg s_btn'"></span></form><span class="tools"><span id="mHolder1"><div id="mCon1"><span>输入法</span></div></span></span><ul id="mMenu1"><div class="mMenu1-tip-arrow"><em></em><ins></ins></div><li><a href="javascript:;" name="ime_hw">手写</a></li><li><a href="javascript:;" name="ime_py">拼音</a></li><li class="ln"></li><li><a href="javascript:;" name="ime_cl">关闭</a></li></ul></div><p id="lk"><a href="http://baike.baidu.com">百科</a>　<a href="http://wenku.baidu.com">文库</a>　<a href="http://www.hao123.com">hao123</a><span> | <a href="//www.baidu.com/more/">更多>></a></span></p><p id="lm"></p></div></div><div id="ftCon"><div id="ftConw"><p id="lh"><a id="seth" onClick="h(this)" href="/" onmousedown="return ns_c({'fm':'behs','tab':'homepage','pos':0})">把百度设为主页</a><a id="setf" href="//www.baidu.com/cache/sethelp/index.html" onmousedown=
    "return ns_c({'fm':'behs','tab':'favorites','pos':0})" target="_blank">把百度设为主页</a><a onmousedown="return ns_c({'fm':'behs','tab':'tj_about'})" href="http://home.baidu.com">关于百度</a><a onmousedown="return ns_c({'fm':'behs','tab':'tj_about_en'})" href="http://ir.baidu.com">About Baidu</a></p><p id="cp">©2018 Baidu <a href="/duty/" name="tj_duty">使用百度前必读</a> 京ICP证030173号 <img src="http://s1.bdstatic.com/r/www/cache/static/global/img/gs_237f015b.gif"></p></div></div><div id="wrapper_wrapper"></div></div><div class="c-tips-container" id="c-tips-container"></div>
    <script>window.__async_strategy=2;</script>
    <script>var bds={se:{},su:{urdata:[],urSendClick:function(){}},util:{},use:{},comm : {domain:"http://www.baidu.com",ubsurl : "http://sclick.baidu.com/w.gif",tn:"baidu",queryEnc:"",queryId:"",inter:"",templateName:"baidu",sugHost : "http://suggestion.baidu.com/su",query : "",qid : "",cid : "",sid : "",indexSid : "",stoken : "",serverTime : "",user
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    ion(e){var $s = iptwr.parent().find('.bdsug');var l = $s.find('li').length;if(l>=5){$s.addClass('bdsugbg');}else{$s.removeClass('bdsugbg');}});}if(btnwr && btn){btnwr.on('mouseover',function(){btn.addClass('btnhover');}).on('mouseout',function(){btn.removeClass('btnhover');});}}});</script>
    <script type="text/javascript" src="http://s1.bdstatic.com/r/www/cache/static/home/js/bri_7f1fa703.js"></script>
    <script>(function(){var _init=false;window.initIndex=function(){if(_init){return;}_init=true;var w=window,d=document,n=navigator,k=d.f1.wd,a=d.getElementById("nv").getElementsByTagName("a"),isIE=n.userAgent.indexOf("MSIE")!=-1&&!window.opera;(function(){if(/q=([^&]+)/.test(location.search)){k.value=decodeURIComponent(RegExp["\x241"])}})();(function(){var u = G("u1").getElementsByTagName("a"), nv = G("nv").getElementsByTagName("a"), lk = G("lk").getElementsByTagName("a"), un = "";var tj_nv = ["news","tieba","zhidao","mp3","img","video","map"];var tj_lk = ["baike","wenku","hao123","more"];un = bds.comm.user == "
    " ? "" : bds.comm.user;function _addTJ(obj){addEV(obj, "mousedown", function(e){var e = e || window.event;var target = e.target || e.srcElement;if(target.name){ns_c({'fm':'behs','tab':target.name,'un':encodeURIComponent(un)});}});}for(var i = 0; i < u.length; i++){_addTJ(u[i]);}for(var i = 0; i < nv.length; i++){nv[i].name = 'tj_' + tj_nv[i];}for(var i = 0; i < lk.length; i++){lk[i].name = 'tj_' + tj_lk[i];}})();(function() {var links = {'tj_news': ['word', 'http://news.baidu.com/ns?tn=news&cl=2&rn=20&ct=1&ie=utf-8'],'tj_tieba': ['kw', 'http://tieba.baidu.com/f?ie=utf-8'],'tj_zhidao': ['word', 'http://zhidao.baidu.com/search?pn=0&rn=10&lm=0'],'tj_mp3': ['key', 'http://music.baidu.com/search?fr=ps&ie=utf-8'],'tj_img': ['word', 'http://image.baidu.com/i?ct=201326592&cl=2&nc=1&lm=-1&st=-1&tn=baiduimage&istype=2&fm=&pv=&z=0&ie=utf-8'],'tj_video': ['word', 'http://video.baidu.com/v?ct=301989888&s=25&ie=utf-8'],'tj_map': ['wd', 'http://map.baidu.com/?newmap=1&ie=utf-8&s=s'],'tj_baike': ['word', 'http://baike.baidu.
    com/search/word?pic=1&sug=1&enc=utf8'],'tj_wenku': ['word', 'http://wenku.baidu.com/search?ie=utf-8']};var domArr = [G('nv'), G('lk'),G('cp')],kw = G('kw1');for (var i = 0, l = domArr.length; i < l; i++) {domArr[i].onmousedown = function(e) {e = e || window.event;var target = e.target || e.srcElement,name = target.getAttribute('name'),items = links[name],reg = new RegExp('^\\s+|\\s+\x24'),key = kw.value.replace(reg, '');if (items) {if (key.length > 0) {var wd = items[0], url = items[1],url = url + ( name === 'tj_map' ? encodeURIComponent('&' + wd + '=' + key) : ( ( url.indexOf('?') > 0 ? '&' : '?' ) + wd + '=' + encodeURIComponent(key) ) );target.href = url;} else {target.href = target.href.match(new RegExp('^http:\/\/.+\.baidu\.com'))[0];}}name && ns_c({'fm': 'behs','tab': name,'query': encodeURIComponent(key),'un': encodeURIComponent(bds.comm.user || '') });};}})();};if(window.pageState==0){initIndex();}})();document.cookie = 'IS_STATIC=1;expires=' + new Date(new Date().getTime() + 10*60*1000).toGMTString()
    ;</script>
    </body></html>

如果不用Java Socket，改用HttpURLConnection,代码如下：

import java.io.BufferedInputStream;
    import java.net.HttpURLConnection;
    import java.net.URL;
    
    public class Test {
    	public static void main(String[] args) {
    		try {
    			Test test = new Test();
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    	}
    
    	public Test() throws Exception {
    		URL url = new URL("http://www.baidu.com");
    		HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
    
    		// 开始读取远程服务器的响应数据。
    		BufferedInputStream bis = new BufferedInputStream(urlConnection.getInputStream());
    
    		byte[] buffer = new byte[1024 * 10];
    		int count = 0;
    		while (true) {
    			count = bis.read(buffer);
    			if (count == -1) {
    				break;
    			}
    
    			System.out.println(new String(buffer, 0, count, "UTF-8"));
    		}
    
    		bis.close();
    	}
    }

运行后输出：

<!DOCTYPE html>
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