HTTP网络编程（客户端）
HTTP协议
浏览器访问过程
- 改文章参考相关链接：https://blog.csdn.net/m_buddy/article/details/77800998
总结起来大概的流程是这样的：
-
浏览器本身是一个客户端，当你输入URL的时候，首先浏览器会去请求DNS服务器，通过DNS获取相应的域名对应的IP
-
然后通过IP地址找到IP对应的服务器后，要求建立TCP连接
-
浏览器发送完HTTP Request（请求）包后，服务器接收到请求包之后才开始处理请求包
-
在服务器收到请求之后，服务器调用自身服务，返回HTTP Response**（响应）包**
-
客户端收到来自服务器的响应后开始渲染这个Response包里的主体（body），等收到全部的内容随后断开与该服务器之间的TCP连接。
域名解析的过程
在浏览器输入一串域名要访问某网站的时候，浏览器帮我们做了如下事情（以Chrome浏览器和windows系统为例）：
-
Chrome浏览器首先检查自己本地是缓存是否有对应的域名，有则直接使用。【查看Chrome浏览器dns缓存地址：chrome://net-internals/#dns】
-
如果浏览器缓存中没有，则查询系统DNS缓存中的域名表，有则直接使用。【windows查看域名表的命令：ipconfig /displaydns】
-
系统缓存中还是没有，则检查hosts文件中的映射表。【windows中hosts文件路径：C:\Windows\System32\drivers\etc】
-
本地实在找不到，则向DNS域名服务器发起请求查询。【DNS服务器IP是本地配置的首选服务器，一般常用的有114.114.114.114（电信运营商提供）和8.8.8.8（Google提供）】
- DNS服务器首先查找自身的缓存，有对应的域名ip则返回结果
- 如果缓存中查找不到，DNS服务器则发起迭代DNS请求，首先向根域服务器发起请求查询，假如本次请求的是www.baidu.com,根域服务器发现这是一个com的顶级域名，就把com域的ip地址返回给DNS服务器
- DNS服务器向com域ip地址发起请求，查询该域名的ip，此时该服务器返回了baidu.com的DNS地址。
- 最后DNS服务器又向baidu.com的DNS地址发起查询请求，最后找到了完整的ip路径返回给DNS服务器，DNS再把ip信息返回给windows内核，内核再返回给浏览器，于是浏览器就知道该域名对应的ip地址了，可以开始进一步请求了。
HTTP请求
连接成功建立后，开始向web服务器发送请求，当浏览器向Web服务器发出请求时，它向服务器传递了一个数据块，也就是请求信息，HTTP请求信息由3部分组成：
- 起始行：HTTP请求方法 URL HTTP版本
- 请求头：请求头的形式通过一个键值对进行渲染
- 请求体：get方法的请求体是没有内容的（放在了url里） post方法的请求体包含请求的内容
下面是一个HTTP请求的例子：
GET /sample.jsp HTTP/1.1
Accept:image/gif.image/jpeg,*/*
Accept-Language:zh-cn
Connection:Keep-Alive
Host:localhost
User-Agent:Mozila/4.0(compatible;MSIE5.01;Window NT5.0)
Accept-Encoding:gzip,deflate
username=jinqiao&password=123412345678
起始行
-
请求的起始行是：”
方法 URL http版本“GET /sample.jsp HTTP/1.1 -
根据HTTP标准，HTTP请求可以使用多种请求方法。例如：HTTP1.1支持7种请求方法：GET、POST、HEAD、OPTIONS、PUT、DELETE和TARCE。在Internet应用中，最常用的方法是GET和POST。
-
URL完整地指定了要访问的网络资源，通常只要给出相对于服务器的根目录的相对目录即可，因此总是以“/”开头。
-
协议版本声明了通信过程中使用HTTP的版本。
请求头(Request Header)
请求头包含许多有关的客户端环境和请求正文的有用信息。例如，请求头可以声明浏览器所用的语言，请求正文的长度等。
Accept:image/gif.image/jpeg.*/*
Accept-Language:zh-cn
Connection:Keep-Alive
Host:localhost
User-Agent:Mozila/4.0(compatible:MSIE5.01:Windows NT5.0)
Accept-Encoding:gzip,deflate.123456
- host表示主机名，User-Agent表示用户代理即浏览器
请求正文
请求头和请求正文之间是一个空行，这个行非常重要，它表示请求头已经结束，接下来的是请求正文。请求正文中可以包含客户提交的查询字符串信息：
username=jinqiao&password=12341
在以上的例子的HTTP请求中，请求的正文只有一行内容。当然，在实际应用中，HTTP请求正文可以包含更多的内容。
HTTP响应
应答 web服务器收到这个请求，进行处理。从它的文档空间中搜索子目录mydir的文件index.html。如果找到该文件，Web服务器把该文件内容传送给相应的Web浏览器。为了告知浏览器，Web服务器首先传送一些HTTP头信息，然后传送具体内容（即HTTP体信息），HTTP头信息和HTTP体信息之间用一个空行分开。
HTTP应答与HTTP请求相似，HTTP响应也由3个部分构成，分别是：
- 起始行：HTTP协议版本 响应状态码 响应状态信息
- 响应头(Response Header) ：通过键值对的形式进行表示
- 响应体： 网页代码 HTML、CSS、JS代码文件
下面是一个HTTP响应的例子：
HTTP/1.1 200 OK
Server:Apache Tomcat/5.0.12
Date:Mon,6Oct2003 13:23:42 GMT
Content-Length:112
HTTP响应示例<title>
</head>
<body>
Hello HTTP!
</body>
</html>
</code></pre>
<p>协议状态代码描述HTTP响应的第一行类似于HTTP请求的第一行，它表示通信所用的协议是HTTP1.1服务器已经成功的处理了客户端发出的请求（200表示成功）:<br> <code>HTTP/1.1 200 OK</code><br> 响应头(Response Header)响应头也和请求头一样包含许多有用的信息，例如服务器类型、日期时间、内容类型和长度等：</p>
<pre><code class="prism language-http">Server:Apache Tomcat/5.0.12
Date:Mon,6Oct2003 13:13:33 GMT
Content-Type:text/html
Last-Moified:Mon,6 Oct 2003 13:23:42 GMT
Content-Length:11212345
</code></pre>
<p>响应体就是服务器返回的HTML页面：</p>
<pre><code class="prism language-http"><html>
<head>
<title>HTTP响应示例<title>
</head>
<body>
Hello HTTP!
</body>
</html>12345678
</code></pre>
<p>响应头和正文之间也必须用<strong>空行</strong>分隔。</p>
<p><strong>HTTP应答码</strong></p>
<p><a href="http://img.e-com-net.com/image/info8/430fa7bc2bd24ea4b2dd021741c5dea7.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/430fa7bc2bd24ea4b2dd021741c5dea7.jpg" alt="HTTP网络编程（客户端）_第2张图片" width="650" height="457" style="border:1px solid black;"></a></p>
<p>HTTP应答码也称为状态码，它反映了Web服务器处理HTTP请求状态。<strong>HTTP应答码由3位数字构成，其中首位数字定义了应答码的类型</strong>：</p>
<ul>
<li> <p>1XX－信息类(Information),表示收到Web浏览器请求，正在进一步的处理中</p> </li>
<li> <p>2XX－成功类（Successful）,表示用户请求被正确接收，理解和处理例如：200 OK</p> </li>
<li> <p>3XX - 重定向类(Redirection),表示请求没有成功，客户必须采取进一步的动作。</p> </li>
<li> <p>4XX - 客户端错误(Client Error)，表示客户端提交的请求有错误 例如：404 NOT Found，意味着请求中所引用的文档不存在。</p> </li>
<li> <p>5XX - 服务器错误(Server Error)表示服务器不能完成对请求的处理：如 500</p> </li>
</ul>
<h5>任务要求：了解 HTTP 协议</h5>
<p>要求：</p>
<ul>
<li>HTTP 协议相关的知识主要包括：
<ul>
<li>HTTP 命令，包括：GET、POST等</li>
<li>HTTP 报文，包括：请求报文头，请求报文体、响应报文头和响应报文体</li>
<li>HTTP 响应状态码</li>
</ul> </li>
<li>阅读 HTTP 协议资料 阅读 HTTP 协议入门 阅读 HTTP 头部字段资料 阅读 HTTP 状态码资料</li>
<li>用 telnet 工具了解 HTTP 协议的相关知识、用 curl 工具了解 HTTP 协议的相关知识、用 chrome 开发者工具了解 HTTP 协议的相关知识</li>
<li>用上面三个工具访问 http://sample.wangding.in/web/one-div.html ，查看请求和响应的头信息</li>
<li>搞明白请求头部字段列表中每个字段的含义和作用</li>
<li>搞明白响应头部字段列表中每个字段的含义和作用</li>
</ul>
<pre><code class="prism language-bash">~ » <span class="token function">curl</span> http://sample.wangding.in/web/one-div.html wangding@OFFICE
<span class="token comment"># 直接返回对应的html文件内容，由于是命令行工具，因此不能够进行渲染</span>
<span class="token operator"><</span><span class="token operator">!</span>DOCTYPE html<span class="token operator">></span>
<span class="token operator"><</span>html<span class="token operator">></span>
<span class="token operator"><</span>head<span class="token operator">></span><span class="token operator"><</span>/head<span class="token operator">></span>
<span class="token operator"><</span>body<span class="token operator">></span><span class="token operator"><</span>/body<span class="token operator">></span>
<span class="token operator"><</span>/html<span class="token operator">></span>
------------------------------------------------------------
~ » <span class="token function">curl</span> http://sample.wangding.in/web/one-div.html -v wangding@OFFICE
<span class="token comment"># 加上参数-v可以直接显示出来对应的所有内容</span>
* About to connect<span class="token punctuation">(</span><span class="token punctuation">)</span> to sample.wangding.in port 80 <span class="token punctuation">(</span><span class="token comment">#0)</span>
* Trying 185.199.109.153<span class="token punctuation">..</span>. <span class="token comment"># dns解析出对应的域名</span>
* Connected to sample.wangding.in <span class="token punctuation">(</span>185.199.109.153<span class="token punctuation">)</span> port 80 <span class="token punctuation">(</span><span class="token comment">#0) # 进行TCP连接</span>
<span class="token operator">></span> GET /web/one-div.html HTTP/1.1
<span class="token operator">></span> User-Agent: curl/7.29.0
<span class="token operator">></span> Host: sample.wangding.in
<span class="token operator">></span> Accept: */*
<span class="token operator">></span>
<span class="token operator"><</span> HTTP/1.1 200 OK
<span class="token operator"><</span> Server: GitHub.com
<span class="token operator"><</span> Content-Type: text/html<span class="token punctuation">;</span> charset<span class="token operator">=</span>utf-8
<span class="token operator"><</span> Last-Modified: Wed, 13 Jun 2018 08:24:27 GMT
<span class="token operator"><</span> ETag: <span class="token string">"5b20d4bb-146"</span>
<span class="token operator"><</span> Access-Control-Allow-Origin: *
<span class="token operator"><</span> Expires: Tue, 30 Oct 2018 07:07:45 GMT
<span class="token operator"><</span> Cache-Control: max-age<span class="token operator">=</span>600
<span class="token operator"><</span> X-GitHub-Request-Id: 2D16:563C:2485737:2FF1319:5BD800E9
<span class="token operator"><</span> Content-Length: 326
<span class="token operator"><</span> Accept-Ranges: bytes
<span class="token operator"><</span> Date: Tue, 30 Oct 2018 07:00:27 GMT
<span class="token operator"><</span> Via: 1.1 varnish
<span class="token operator"><</span> Age: 162
<span class="token operator"><</span> Connection: keep-alive
<span class="token operator"><</span> X-Served-By: cache-hkg17921-HKG
<span class="token operator"><</span> X-Cache: HIT
<span class="token operator"><</span> X-Cache-Hits: 4
<span class="token operator"><</span> X-Timer: S1540882828.772362,VS0,VE0
<span class="token operator"><</span> Vary: Accept-Encoding
<span class="token operator"><</span> X-Fastly-Request-ID: 84d0102672d42d756ed3d4ef8a8c8f7ccea8b776
<span class="token operator"><</span>
<span class="token operator"><</span><span class="token operator">!</span>DOCTYPE html<span class="token operator">></span>
<span class="token operator"><</span>html<span class="token operator">></span>
<span class="token operator"><</span>head<span class="token operator">></span>
<span class="token operator"><</span>meta charset<span class="token operator">=</span><span class="token string">"UTF-8"</span><span class="token operator">></span>
<span class="token operator"><</span>title<span class="token operator">></span><span class="token operator"><</span><span class="token operator">></span>ne div game<span class="token operator"><</span>/title<span class="token operator">></span>
<span class="token operator"><</span>style type<span class="token operator">=</span><span class="token string">"text/css"</span><span class="token operator">></span>
<span class="token comment">#game {</span>
width: 100px<span class="token punctuation">;</span>
height: 100px<span class="token punctuation">;</span>
background-color: green<span class="token punctuation">;</span>
margin: 100px auto<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token operator"><</span>/style<span class="token operator">></span>
<span class="token operator"><</span>/head<span class="token operator">></span>
<span class="token operator"><</span>body<span class="token operator">></span>
<span class="token operator"><</span>div id<span class="token operator">=</span><span class="token string">"game"</span><span class="token operator">></span><span class="token operator"><</span>/div<span class="token operator">></span>
<span class="token operator"><</span>/body<span class="token operator">></span>
<span class="token operator"><</span>/html<span class="token operator">></span>
* Connection <span class="token comment">#0 to host sample.wangding.in left intact</span>
</code></pre>
<p></p>
<h4>GET和POST方法</h4>
<ul>
<li>get方法</li>
</ul>
<p><a href="http://img.e-com-net.com/image/info8/3202501015614f70a824ce7ed3a265ee.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/3202501015614f70a824ce7ed3a265ee.jpg" alt="HTTP网络编程（客户端）_第3张图片" width="533" height="304" style="border:1px solid black;"></a></p>
<ul>
<li>post方法</li>
</ul>
<p><a href="http://img.e-com-net.com/image/info8/b35b53a89f32423b8d2c57fbe8308d21.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/b35b53a89f32423b8d2c57fbe8308d21.jpg" alt="HTTP网络编程（客户端）_第4张图片" width="564" height="293" style="border:1px solid black;"></a></p>
<p><a href="http://img.e-com-net.com/image/info8/654e809800854a089469a6bf157a1876.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/654e809800854a089469a6bf157a1876.jpg" alt="HTTP网络编程（客户端）_第5张图片" width="650" height="422" style="border:1px solid black;"></a></p>
<h5>实现 HTTP 客户端</h5>
<ul>
<li>可以解释命令行参数，命令行参数是要请求的 URL 地址</li>
<li>向指定的 URL 地址发出 GET 请求</li>
<li>将 HTTP 响应的报文头和报文体内容打印到控制台</li>
<li>用 http 模块的 get 方法</li>
<li>定义 user-agent 为 01-my-curl</li>
</ul>
<pre><code class="prism language-javascript">#<span class="token operator">!</span><span class="token operator">/</span>usr<span class="token operator">/</span>bin<span class="token operator">/</span>node
<span class="token keyword">const</span> http <span class="token operator">=</span> <span class="token function">require</span><span class="token punctuation">(</span><span class="token string">'http'</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
url <span class="token operator">=</span> <span class="token function">require</span><span class="token punctuation">(</span><span class="token string">'url'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">var</span> address <span class="token operator">=</span> process<span class="token punctuation">.</span>argv<span class="token punctuation">[</span><span class="token number">2</span><span class="token punctuation">]</span> <span class="token operator">||</span> <span class="token string">'http://localhost:8080'</span><span class="token punctuation">;</span>
<span class="token keyword">const</span> options <span class="token operator">=</span> <span class="token punctuation">{</span>
hostname<span class="token punctuation">:</span>url<span class="token punctuation">.</span><span class="token function">parse</span><span class="token punctuation">(</span>address<span class="token punctuation">)</span><span class="token punctuation">.</span>hostname<span class="token punctuation">,</span>
prot<span class="token punctuation">:</span>url<span class="token punctuation">.</span><span class="token function">parse</span><span class="token punctuation">(</span>address<span class="token punctuation">)</span><span class="token punctuation">.</span>prot<span class="token punctuation">,</span>
path<span class="token punctuation">:</span>url<span class="token punctuation">.</span><span class="token function">parse</span><span class="token punctuation">(</span>address<span class="token punctuation">)</span><span class="token punctuation">.</span>pathname<span class="token punctuation">,</span>
headers<span class="token punctuation">:</span><span class="token punctuation">{</span>
<span class="token string">'User-Agent'</span><span class="token punctuation">:</span><span class="token string">'01-my-curl'</span><span class="token punctuation">,</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
http<span class="token punctuation">.</span><span class="token keyword">get</span><span class="token punctuation">(</span>options<span class="token punctuation">,</span><span class="token punctuation">(</span>res<span class="token punctuation">)</span><span class="token operator">=></span><span class="token punctuation">{</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'http/'</span><span class="token operator">+</span>res<span class="token punctuation">.</span>httpVersion<span class="token punctuation">,</span>res<span class="token punctuation">.</span>statusCode<span class="token punctuation">,</span>res<span class="token punctuation">.</span>statusMessage<span class="token punctuation">)</span><span class="token punctuation">;</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>res<span class="token punctuation">.</span>headers<span class="token punctuation">)</span><span class="token punctuation">;</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
res<span class="token punctuation">.</span><span class="token function">pipe</span><span class="token punctuation">(</span>process<span class="token punctuation">.</span>stdout<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre>
<pre><code class="prism language-bash"><span class="token comment"># 程序运行结果</span>
~/node.js/nodejs-demo/16-http<span class="token punctuation">(</span>master*<span class="token punctuation">)</span> » ./01-my-curl.js
http/1.1 200 OK
<span class="token punctuation">{</span> date: <span class="token string">'Tue, 30 Oct 2018 13:01:33 GMT'</span>,
connection: <span class="token string">'close'</span>,
<span class="token string">'content-length'</span><span class="token keyword">:</span> <span class="token string">'11'</span> <span class="token punctuation">}</span>
hello world%
~/node.js/nodejs-demo/01-introduction<span class="token punctuation">(</span>master*<span class="token punctuation">)</span> » ./02-hello-world-server.js
<span class="token comment"># 定义 user-agent 为 01-my-curl</span>
<span class="token punctuation">{</span> <span class="token string">'user-agent'</span><span class="token keyword">:</span> <span class="token string">'01-my-curl'</span>,
host: <span class="token string">'localhost:8080'</span>,
connection: <span class="token string">'close'</span> <span class="token punctuation">}</span>
</code></pre>
<h5>对 HTTP 接口发出 GET 请求</h5>
<ul>
<li> <p>调用天气预报 API，实现城市天气查询：https://www.juhe.cn/docs/api/id/39</p> </li>
<li> <p>用 GET 方法请求天气信息</p> </li>
<li> <p>获取某个账户的所有 GitHub 仓库的数量和名称</p> </li>
<li> <p>API 地址：<code>https://api.github.com/search/repositories?q=user:wangding</code></p> </li>
<li> <p>API 参考：https://developer.github.com/v3/</p> </li>
</ul>
<pre><code class="prism language-javascript"><span class="token comment">/*get-weather*/</span>
#<span class="token operator">!</span><span class="token operator">/</span>usr<span class="token operator">/</span>bin<span class="token operator">/</span>node
<span class="token keyword">const</span> http <span class="token operator">=</span> <span class="token function">require</span><span class="token punctuation">(</span><span class="token string">'http'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">var</span> city <span class="token operator">=</span> process<span class="token punctuation">.</span>argv<span class="token punctuation">[</span><span class="token number">2</span><span class="token punctuation">]</span> <span class="token operator">||</span> <span class="token string">'石家庄'</span><span class="token punctuation">;</span>
<span class="token keyword">var</span> address <span class="token operator">=</span> <span class="token string">'http://v.juhe.cn/weather/index?format=2&cityname='</span><span class="token operator">+</span> city <span class="token operator">+</span> <span class="token string">'&key=089c1db918016aa1643dcc167dc789fb'</span><span class="token punctuation">;</span>
http<span class="token punctuation">.</span><span class="token keyword">get</span><span class="token punctuation">(</span>global<span class="token punctuation">.</span><span class="token function">encodeURI</span><span class="token punctuation">(</span>address<span class="token punctuation">)</span><span class="token punctuation">,</span><span class="token punctuation">(</span>res<span class="token punctuation">)</span><span class="token operator">=></span><span class="token punctuation">{</span>
<span class="token keyword">var</span> result <span class="token operator">=</span> <span class="token string">''</span><span class="token punctuation">;</span>
res<span class="token punctuation">.</span><span class="token function">on</span><span class="token punctuation">(</span><span class="token string">'data'</span><span class="token punctuation">,</span><span class="token punctuation">(</span>data<span class="token punctuation">)</span><span class="token operator">=></span><span class="token punctuation">{</span>
result <span class="token operator">+=</span> data<span class="token punctuation">.</span><span class="token function">toString</span><span class="token punctuation">(</span><span class="token string">'utf-8'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
res<span class="token punctuation">.</span><span class="token function">on</span><span class="token punctuation">(</span><span class="token string">'end'</span><span class="token punctuation">,</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token operator">=></span><span class="token punctuation">{</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token constant">JSON</span><span class="token punctuation">.</span><span class="token function">parse</span><span class="token punctuation">(</span>result<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre>
<pre><code class="prism language-javascript"><span class="token comment">/*get-repos*/</span>
#<span class="token operator">!</span><span class="token operator">/</span>usr<span class="token operator">/</span>bin<span class="token operator">/</span>node
<span class="token keyword">const</span> http <span class="token operator">=</span> <span class="token function">require</span><span class="token punctuation">(</span><span class="token string">'http'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">var</span>
</code></pre>
<h5>发起 POST 请求</h5>
<ul>
<li>编写 03-post.js 脚本，向指定的 URL 地址发出 HTTP POST 请求</li>
<li>并且 POST 请求中，携带向服务器程序发送的特定数据</li>
<li>将 HTTP 响应的报文头和报文体内容打印到控制台</li>
<li>编写 03-server.js 脚本，接收 03-post.js 脚本发送的 POST 请求数据</li>
<li>将接收到的数据打开到控制台</li>
</ul>
<pre><code class="prism language-javascript"><span class="token comment">/*03-server.js*/</span>
#<span class="token operator">!</span><span class="token operator">/</span>usr<span class="token operator">/</span>bin<span class="token operator">/</span>node
<span class="token keyword">const</span> http <span class="token operator">=</span> <span class="token function">require</span><span class="token punctuation">(</span><span class="token string">'http'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
http<span class="token punctuation">.</span><span class="token function">createServer</span><span class="token punctuation">(</span><span class="token punctuation">(</span>req<span class="token punctuation">,</span>res<span class="token punctuation">)</span><span class="token operator">=></span><span class="token punctuation">{</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>req<span class="token punctuation">.</span>headers<span class="token punctuation">)</span><span class="token punctuation">;</span>
req<span class="token punctuation">.</span><span class="token function">pipe</span><span class="token punctuation">(</span>process<span class="token punctuation">.</span>stdout<span class="token punctuation">)</span><span class="token punctuation">;</span>
res<span class="token punctuation">.</span><span class="token function">end</span><span class="token punctuation">(</span><span class="token string">'OK!'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">listen</span><span class="token punctuation">(</span><span class="token number">8080</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre>
<pre><code class="prism language-javascript"><span class="token comment">/*03-post.js*/</span>
#<span class="token operator">!</span><span class="token operator">/</span>usr<span class="token operator">/</span>bin<span class="token operator">/</span>node
<span class="token keyword">const</span> http <span class="token operator">=</span> <span class="token function">require</span><span class="token punctuation">(</span><span class="token string">'http'</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
url <span class="token operator">=</span> <span class="token function">require</span><span class="token punctuation">(</span><span class="token string">'url'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">var</span> address <span class="token operator">=</span> process<span class="token punctuation">.</span>argv<span class="token punctuation">[</span><span class="token number">2</span><span class="token punctuation">]</span> <span class="token operator">||</span> <span class="token string">'http://localhost:8080'</span><span class="token punctuation">;</span>
<span class="token keyword">const</span> options <span class="token operator">=</span> <span class="token punctuation">{</span>
hostname<span class="token punctuation">:</span>url<span class="token punctuation">.</span><span class="token function">parse</span><span class="token punctuation">(</span>address<span class="token punctuation">)</span><span class="token punctuation">.</span>hostname<span class="token punctuation">;</span>
prot<span class="token punctuation">:</span>url<span class="token punctuation">.</span><span class="token function">parse</span><span class="token punctuation">(</span>address<span class="token punctuation">)</span><span class="token punctuation">.</span>prot<span class="token punctuation">,</span>
path<span class="token punctuation">:</span>url<span class="token punctuation">.</span><span class="token function">parse</span><span class="token punctuation">(</span>address<span class="token punctuation">)</span><span class="token punctuation">.</span>pathname<span class="token punctuation">,</span>
method<span class="token punctuation">:</span><span class="token string">'POST'</span><span class="token punctuation">,</span>
headers<span class="token punctuation">:</span><span class="token punctuation">{</span>
<span class="token string">'User-Agent'</span><span class="token punctuation">:</span><span class="token string">'03-server'</span><span class="token punctuation">,</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span><span class="token punctuation">;</span>
<span class="token keyword">const</span> req <span class="token operator">=</span> http<span class="token punctuation">.</span><span class="token function">request</span><span class="token punctuation">(</span>options<span class="token punctuation">,</span><span class="token punctuation">(</span>res<span class="token punctuation">)</span><span class="token operator">=></span><span class="token punctuation">{</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'http/'</span><span class="token operator">+</span>res<span class="token punctuation">.</span>httpVersion<span class="token punctuation">,</span>res<span class="token punctuation">.</span>statusCode<span class="token punctuation">,</span>res<span class="token punctuation">.</span>statusMessage<span class="token punctuation">)</span><span class="token punctuation">;</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>res<span class="token punctuation">.</span>headers<span class="token punctuation">)</span><span class="token punctuation">;</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
res<span class="token punctuation">.</span><span class="token function">pipe</span><span class="token punctuation">(</span>process<span class="token punctuation">.</span>stdout<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
req<span class="token punctuation">.</span><span class="token function">write</span><span class="token punctuation">(</span><span class="token string">"{'name':'wangding'}'"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
req<span class="token punctuation">.</span><span class="token function">end</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre>
<p>程序运行结果</p>
<pre><code class="prism language-bash"><span class="token comment"># 前台得到的消息</span>
~/node.js/nodejs-demo/16-http<span class="token punctuation">(</span>master*<span class="token punctuation">)</span> » ./03-post.js wangding@OFFICE
HTTP/1.1 200 OK
<span class="token punctuation">{</span> date: <span class="token string">'Tue, 30 Oct 2018 13:19:48 GMT'</span>,
connection: <span class="token string">'close'</span>,
<span class="token string">'content-length'</span><span class="token keyword">:</span> <span class="token string">'3'</span> <span class="token punctuation">}</span>
OK<span class="token operator">!</span>%
<span class="token comment"># 服务器得到的消息</span>
~/node.js/nodejs-demo/16-http<span class="token punctuation">(</span>master*<span class="token punctuation">)</span> » ./03-server.js wangding@OFFICE
<span class="token punctuation">{</span> <span class="token string">'user-agent'</span><span class="token keyword">:</span> <span class="token string">'03-server'</span>,
host: <span class="token string">'localhost:8080'</span>,
connection: <span class="token string">'close'</span>,
<span class="token string">'transfer-encoding'</span><span class="token keyword">:</span> <span class="token string">'chunked'</span> <span class="token punctuation">}</span>
<span class="token punctuation">{</span><span class="token string">""</span>name<span class="token string">":"</span>wangding<span class="token string">""</span><span class="token punctuation">}</span>
</code></pre>
<h4>编写爬虫程序</h4>
<ul>
<li>创建 04-crawler 目录，创建项目配置文件：package.json</li>
<li><code>npm i -S cheerio</code> 安装项目依赖 cheerio</li>
<li>用 cheerio 对爬取的 HTML 页面进行 DOM 元素解析</li>
<li>cheerio 用法请参考：cheerio API</li>
<li>爬取 51CTO 学院所有的免费课程信息</li>
<li>需爬取的网页地址：http://edu.51cto.com/courselist/index-zh5.html</li>
<li>从爬取的网页中解析出课程信息，包括：课程名称，课程时长，课程地址，教学目标</li>
<li>将爬取的课程信息格式化输出到控制台</li>
<li>实现多任务并发爬取</li>
</ul>
<pre><code class="prism language-javascript"><span class="token comment">/*
1. npm init 创建项目配置文件
2. npm i -S cheerio 安装项目依赖cheerio (i的目的是为了自动加入到package.json上去)
*/</span>
#<span class="token operator">!</span><span class="token operator">/</span>usr<span class="token operator">/</span>bin<span class="token operator">/</span>node
<span class="token keyword">const</span> http <span class="token operator">=</span> <span class="token function">require</span><span class="token punctuation">(</span><span class="token string">'http'</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
cheerio <span class="token operator">=</span> <span class="token function">require</span><span class="token punctuation">(</span><span class="token string">'cheerio'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">var</span> i <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">;</span>i<span class="token operator"><</span><span class="token number">87</span><span class="token punctuation">;</span>i<span class="token operator">++</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
<span class="token keyword">var</span> address <span class="token operator">=</span> <span class="token string">'http://edu.51cto.com/courselist/index-zh5-p'</span> <span class="token operator">+</span> i <span class="token operator">+</span> <span class="token string">'.html'</span><span class="token punctuation">;</span>
http<span class="token punctuation">.</span><span class="token keyword">get</span><span class="token punctuation">(</span>address<span class="token punctuation">,</span><span class="token punctuation">(</span>res<span class="token punctuation">)</span><span class="token operator">=></span><span class="token punctuation">{</span>
<span class="token keyword">var</span> html <span class="token operator">=</span> <span class="token string">''</span><span class="token punctuation">;</span>
res<span class="token punctuation">.</span><span class="token function">on</span><span class="token punctuation">(</span><span class="token string">'data'</span><span class="token punctuation">,</span><span class="token punctuation">(</span>data<span class="token punctuation">)</span><span class="token operator">=></span><span class="token punctuation">{</span>
html <span class="token operator">+=</span>data<span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
res<span class="token punctuation">.</span><span class="token function">on</span><span class="token punctuation">(</span><span class="token string">'end'</span><span class="token punctuation">,</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token operator">=></span><span class="token punctuation">{</span>
<span class="token comment">// 沿用JQuery风格，定义$</span>
<span class="token keyword">var</span> $ <span class="token operator">=</span> cheerio<span class="token punctuation">.</span><span class="token function">load</span><span class="token punctuation">(</span>html<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token function">$</span><span class="token punctuation">(</span><span class="token string">'body'</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span><span class="token string">'div.main'</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">each</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
<span class="token keyword">var</span> cName <span class="token operator">=</span> <span class="token function">$</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span><span class="token string">'a'</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">text</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
cTime <span class="token operator">=</span> <span class="token function">$</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span><span class="token string">'p.fl'</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">text</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
cTarget <span class="token operator">=</span> <span class="token function">$</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span><span class="token string">'div.course_target'</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">text</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
cUrl <span class="token operator">=</span> <span class="token function">$</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span><span class="token string">'a'</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">attr</span><span class="token punctuation">(</span><span class="token string">'href'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">if</span><span class="token punctuation">(</span>cTime <span class="token operator">===</span> <span class="token string">''</span><span class="token punctuation">)</span> <span class="token keyword">return</span><span class="token punctuation">;</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'课程名称：'</span><span class="token punctuation">,</span>cName<span class="token punctuation">)</span><span class="token punctuation">;</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'课程时长：'</span><span class="token punctuation">,</span>cTime<span class="token punctuation">)</span><span class="token punctuation">;</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'课程目标：'</span><span class="token punctuation">,</span>cTarget<span class="token punctuation">)</span><span class="token punctuation">;</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'课程地址：'</span><span class="token punctuation">,</span>cUrl<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token comment">/*
运行结果
./index.js > out.html 重定向到了out.html里面
cat out | wc -l 统计out.html的行数
9856
*/</span>
</code></pre>
<h4>处理 HTTP 重定向</h4>
<ul>
<li>实现对 HTTP 协议的重定向状态的处理</li>
<li>测试 URL：http://www.sian.com/</li>
<li>需要获取重定向后的最终页面</li>
<li>将最终页面输出到控制台</li>
</ul>
<p>程序运行结果</p>
<p><a href="http://img.e-com-net.com/image/info8/e0228297a5cf495086f0e659460e8f08.png" target="_blank"><img src="http://img.e-com-net.com/image/info8/e0228297a5cf495086f0e659460e8f08.png" alt="HTTP网络编程（客户端）_第6张图片" width="616" height="165" style="border:1px solid black;"></a></p>
<p><a href="http://img.e-com-net.com/image/info8/a8b35d16f8ba4bae84d380cdef1980a7.png" target="_blank"><img src="http://img.e-com-net.com/image/info8/a8b35d16f8ba4bae84d380cdef1980a7.png" alt="HTTP网络编程（客户端）_第7张图片" width="561" height="166" style="border:1px solid black;"></a></p>
<p><a href="http://img.e-com-net.com/image/info8/5a6b98df90e94edbae10aa8de90ff2f6.png" target="_blank"><img src="http://img.e-com-net.com/image/info8/5a6b98df90e94edbae10aa8de90ff2f6.png" alt="HTTP网络编程（客户端）_第8张图片" width="625" height="158" style="border:1px solid black;"></a></p>
<p><a href="http://img.e-com-net.com/image/info8/271ae4086a094d849eba03277aae9866.jpg" target="_blank"><img src="http://img.e-com-net.com/image/info8/271ae4086a094d849eba03277aae9866.jpg" alt="HTTP网络编程（客户端）_第9张图片" width="650" height="216" style="border:1px solid black;"></a></p>
<pre><code class="prism language-javascript">#<span class="token operator">!</span><span class="token operator">/</span>usr<span class="token operator">/</span>bin<span class="token operator">/</span>node
<span class="token keyword">const</span> http <span class="token operator">=</span> <span class="token function">require</span><span class="token punctuation">(</span><span class="token string">'http'</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
url <span class="token operator">=</span> <span class="token function">require</span><span class="token punctuation">(</span><span class="token string">'url'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">var</span> address <span class="token operator">=</span> <span class="token string">'http://www.sian.com/'</span><span class="token punctuation">;</span>
<span class="token keyword">function</span> <span class="token function">getOption</span><span class="token punctuation">(</span>addr<span class="token punctuation">)</span><span class="token punctuation">{</span>
<span class="token keyword">var</span> options <span class="token operator">=</span> url<span class="token punctuation">.</span><span class="token function">parse</span><span class="token punctuation">(</span>address<span class="token punctuation">)</span><span class="token punctuation">;</span>
options<span class="token punctuation">.</span>headers <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token string">'User-Agent'</span><span class="token punctuation">:</span><span class="token string">'curl/7.0'</span><span class="token punctuation">}</span><span class="token punctuation">;</span>
<span class="token keyword">return</span> options<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">function</span> <span class="token function">getUrl</span><span class="token punctuation">(</span>options<span class="token punctuation">)</span><span class="token punctuation">{</span>
http<span class="token punctuation">.</span><span class="token function">createServer</span><span class="token punctuation">(</span><span class="token punctuation">(</span>req<span class="token punctuation">,</span>res<span class="token punctuation">)</span><span class="token operator">=></span><span class="token punctuation">{</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'HTTP/'</span> <span class="token operator">+</span> res<span class="token punctuation">.</span>httpVersion<span class="token punctuation">,</span>res<span class="token punctuation">.</span>statusCode<span class="token punctuation">,</span>res<span class="token punctuation">.</span>statusMessage<span class="token punctuation">)</span><span class="token punctuation">;</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>res<span class="token punctuation">.</span>headers<span class="token punctuation">)</span><span class="token punctuation">;</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">if</span><span class="token punctuation">(</span>res<span class="token punctuation">.</span>statusCode <span class="token operator">></span> <span class="token number">300</span> <span class="token operator">&&</span> res<span class="token punctuation">.</span>statusCode <span class="token operator"><</span><span class="token number">400</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
<span class="token keyword">var</span> newAddr <span class="token operator">=</span> res<span class="token punctuation">.</span>headers<span class="token punctuation">[</span><span class="token string">'location'</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
<span class="token function">getUrl</span><span class="token punctuation">(</span><span class="token function">getOption</span><span class="token punctuation">(</span>newAddr<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token keyword">else</span><span class="token punctuation">{</span>
res<span class="token punctuation">.</span><span class="token function">pipe</span><span class="token punctuation">(</span>process<span class="token punctuation">.</span>stdout<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token function">getUrl</span><span class="token punctuation">(</span><span class="token function">getOption</span><span class="token punctuation">(</span>address<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre>
<p>程序运行结果</p>
<pre><code class="prism language-bash">~/node.js/nodejs-demo/16-http<span class="token punctuation">(</span>master*<span class="token punctuation">)</span> » ./05-redirection.js wangding@OFFIC
HTTP/1.1 301 Moved Permanently
<span class="token punctuation">{</span> server: <span class="token string">'nginx/1.8.0'</span>,
date: <span class="token string">'Wed, 31 Oct 2018 09:52:41 GMT'</span>,
<span class="token string">'content-type'</span><span class="token keyword">:</span> <span class="token string">'text/html'</span>,
<span class="token string">'content-length'</span><span class="token keyword">:</span> <span class="token string">'184'</span>,
connection: <span class="token string">'close'</span>,
location: <span class="token string">'http://sian.com/'</span> <span class="token punctuation">}</span>
HTTP/1.1 302 Moved Temporarily
<span class="token punctuation">{</span> server: <span class="token string">'nginx/1.8.0'</span>,
date: <span class="token string">'Wed, 31 Oct 2018 09:52:42 GMT'</span>,
<span class="token string">'content-type'</span><span class="token keyword">:</span> <span class="token string">'text/html'</span>,
<span class="token string">'content-length'</span><span class="token keyword">:</span> <span class="token string">'160'</span>,
connection: <span class="token string">'close'</span>,
location: <span class="token string">'http://www.sportsworldtl.com/'</span> <span class="token punctuation">}</span>
HTTP/1.1 302 Moved Temporarily
<span class="token punctuation">{</span> server: <span class="token string">'Apache-Coyote/1.1'</span>,
<span class="token string">'set-cookie'</span><span class="token keyword">:</span> <span class="token punctuation">[</span> <span class="token string">'JSESSIONID=C3F4D55A3A87FE4E2CF2E881A0ECA371; Path=/; HttpOnly'</span> <span class="token punctuation">]</span>,
location: <span class="token string">'http://www.sportsworldtl.com/index.ac'</span>,
<span class="token string">'content-type'</span><span class="token keyword">:</span> <span class="token string">'text/html;charset=UTF-8'</span>,
<span class="token string">'content-length'</span><span class="token keyword">:</span> <span class="token string">'0'</span>,
date: <span class="token string">'Wed, 31 Oct 2018 09:52:42 GMT'</span>,
connection: <span class="token string">'close'</span> <span class="token punctuation">}</span>
HTTP/1.1 200 OK
<span class="token punctuation">{</span> server: <span class="token string">'Apache-Coyote/1.1'</span>,
<span class="token string">'set-cookie'</span><span class="token keyword">:</span> <span class="token punctuation">[</span> <span class="token string">'JSESSIONID=077BD21F2C6A2B594F1EE36956398E2C; Path=/; HttpOnly'</span> <span class="token punctuation">]</span>,
<span class="token string">'content-type'</span><span class="token keyword">:</span> <span class="token string">'text/html;charset=utf-8'</span>,
<span class="token string">'content-language'</span><span class="token keyword">:</span> <span class="token string">'zh-CN'</span>,
<span class="token string">'content-length'</span><span class="token keyword">:</span> <span class="token string">'1640'</span>,
vary: <span class="token string">'Accept-Encoding'</span>,
date: <span class="token string">'Wed, 31 Oct 2018 09:52:42 GMT'</span>,
connection: <span class="token string">'close'</span> <span class="token punctuation">}</span>
<span class="token operator"><</span><span class="token operator">!</span>DOCTYPE html<span class="token operator">></span>
<span class="token operator"><</span><span class="token operator">!</span>--<span class="token punctuation">[</span>if IE 8<span class="token punctuation">]</span><span class="token operator">></span> <span class="token operator"><</span>html lang<span class="token operator">=</span><span class="token string">"zh-CN"</span> class<span class="token operator">=</span><span class="token string">"ie8 no-js"</span><span class="token operator">></span> <span class="token operator"><</span><span class="token operator">!</span><span class="token punctuation">[</span>endif<span class="token punctuation">]</span>--<span class="token operator">></span><span class="token operator"><</span><span class="token operator">!</span>--<span class="token punctuation">[</span>if IE 9<span class="token punctuation">]</span><span class="token operator">></span> <span class="token operator"><</span>html lang<span class="token operator">=</span><span class="token string">"zh-CN"</span> class<span class="token operator">=</span><span class="token string">"ie9 no-js"</span><span class="token operator">></span> <span class="token operator"><</span><span class="token operator">!</span><span class="token punctuation">[</span>endif<span class="token punctuation">]</span>--<span class="token operator">></span><span class="token operator"><</span><span class="token operator">!</span>--<span class="token punctuation">[</span>if <span class="token operator">!</span>IE<span class="token punctuation">]</span><span class="token operator">></span><span class="token operator"><</span><span class="token operator">!</span>--<span class="token operator">></span> <span class="token operator"><</span>html lang<span class="token operator">=</span><span class="token string">"zh-CN"</span> class<span class="token operator">=</span><span class="token string">"no-js"</span><span class="token operator">></span> <span class="token operator"><</span><span class="token operator">!</span>--<span class="token operator"><</span><span class="token operator">!</span><span class="token punctuation">[</span>endif<span class="token punctuation">]</span>--<span class="token operator">></span>
<span class="token operator"><</span><span class="token operator">!</span>-- END BODY --<span class="token operator">></span>
<span class="token operator"><</span>/html<span class="token operator">></span>
</code></pre>
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<a class="tag" taget="_blank" href="/search/%E5%89%8D%E7%AB%AF%E5%B0%8F%E7%A8%8B%E5%BA%8F/1.htm">前端小程序</a><a class="tag" taget="_blank" href="/search/%E5%BE%AE%E4%BF%A1%E5%B0%8F%E7%A8%8B%E5%BA%8F/1.htm">微信小程序</a><a class="tag" taget="_blank" href="/search/%E5%89%8D%E7%AB%AF/1.htm">前端</a>
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<a class="tag" taget="_blank" href="/search/Android/1.htm">Android</a><a class="tag" taget="_blank" href="/search/android/1.htm">android</a><a class="tag" taget="_blank" href="/search/%E6%9C%8D%E5%8A%A1%E5%99%A8/1.htm">服务器</a>
<div>在安卓开发中，将本地日志上传到服务器是一个常见的需求，特别是在开发需要远程监控或调试的应用时。以下是一个基本的步骤和示例，说明如何实现这一功能：1本地日志上传到服务器1.1准备服务器首先，你需要在服务器上设置一个接口，用于接收上传的日志文件。这个接口可以是RESTfulAPI，使用HTTPPOST方法接收文件。你可以使用各种后端技术栈来实现这个接口，如Node.js、Python（Flask或Dj</div>
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title="Vue 图片预览功能实现指南" target="_blank">Vue 图片预览功能实现指南</a>
<span class="text-muted">繁依Fanyi</span>
<a class="tag" taget="_blank" href="/search/vue.js/1.htm">vue.js</a><a class="tag" taget="_blank" href="/search/%E5%89%8D%E7%AB%AF/1.htm">前端</a><a class="tag" taget="_blank" href="/search/javascript/1.htm">javascript</a><a class="tag" taget="_blank" href="/search/python/1.htm">python</a><a class="tag" taget="_blank" href="/search/%E4%BA%BA%E5%B7%A5%E6%99%BA%E8%83%BD/1.htm">人工智能</a><a class="tag" taget="_blank" href="/search/%E7%AE%97%E6%B3%95/1.htm">算法</a><a class="tag" taget="_blank" href="/search/%E5%BC%80%E5%8F%91%E8%AF%AD%E8%A8%80/1.htm">开发语言</a>
<div>1.介绍在现代web应用程序中，图片预览功能提升了用户体验，使用户可以在上传图片之前查看图片内容。本文将详细介绍如何在Vue.js应用中实现图片预览功能，包括基本实现、进阶功能、与ElementUI的集成、常见优化技巧以及与其他库的结合使用。2.基本功能实现2.1环境准备确保你的开发环境已经配置好，包括VueCLI和Node.js。如果还没有安装VueCLI，你可以通过以下命令安装：npminst</div>
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title="npm install 太慢？解决方法大揭秘" target="_blank">npm install 太慢？解决方法大揭秘</a>
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<a class="tag" taget="_blank" href="/search/npm/1.htm">npm</a><a class="tag" taget="_blank" href="/search/%E5%89%8D%E7%AB%AF/1.htm">前端</a><a class="tag" taget="_blank" href="/search/node.js/1.htm">node.js</a>
<div>本文将详细介绍如何解决npminstall命令执行速度慢的问题。文章将涵盖npminstall命令执行慢的原因、优化方法以及实际应用案例。通过本文的学习，读者可以掌握提高npminstall命令执行速度的基本技巧，并在实际项目中得心应手。引言npminstall是Node.js项目开发中的常用命令，用于安装项目依赖。然而，在某些情况下，npminstall命令的执行速度可能会变得非常慢，这可能影响</div>
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<span class="text-muted">QGC二次开发</span>
<a class="tag" taget="_blank" href="/search/vue.js/1.htm">vue.js</a><a class="tag" taget="_blank" href="/search/vue/1.htm">vue</a><a class="tag" taget="_blank" href="/search/node.js/1.htm">node.js</a><a class="tag" taget="_blank" href="/search/%E5%BC%80%E5%8F%91%E8%AF%AD%E8%A8%80/1.htm">开发语言</a><a class="tag" taget="_blank" href="/search/%E4%BF%A1%E6%81%AF%E5%8F%AF%E8%A7%86%E5%8C%96/1.htm">信息可视化</a>
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<span class="text-muted">洋baby</span>
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<span class="text-muted">逆旅行天涯</span>
<a class="tag" taget="_blank" href="/search/npm/1.htm">npm</a><a class="tag" taget="_blank" href="/search/%E5%89%8D%E7%AB%AF/1.htm">前端</a><a class="tag" taget="_blank" href="/search/node.js/1.htm">node.js</a>
<div>在Node.js开发过程中，npminstall是安装和管理项目依赖的关键命令。然而，有时我们会遇到npminstall运行卡住不动的情况，这通常与网络连接、NPM源的可用性和速度、资源下载超时等因素有关。本文将为你提供七种解决方案，帮助你顺利进行依赖安装。1.检查网络状况首要任务是确保您的计算机具有稳定的网络连接，并能无障碍访问外部资源。如果是在公司或校园内网环境下，检查是否存在防火墙限制或代理</div>
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title="Node.js 、Yarn、npm、Vue、Vite、Webpack 前端一套流程" target="_blank">Node.js 、Yarn、npm、Vue、Vite、Webpack 前端一套流程</a>
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<a class="tag" taget="_blank" href="/search/%E5%89%8D%E7%AB%AF%E5%BC%80%E5%8F%91/1.htm">前端开发</a><a class="tag" taget="_blank" href="/search/node.js/1.htm">node.js</a><a class="tag" taget="_blank" href="/search/%E5%89%8D%E7%AB%AF/1.htm">前端</a><a class="tag" taget="_blank" href="/search/npm/1.htm">npm</a>
<div>前端项目的搭建Vue、Vite、Webpack、Yarn、Node.js和npm的概念解释，以及它们之间的关系：Node.js：一个开源、跨平台的JavaScript运行时环境，可以让JavaScript代码在服务器端运行。它提供了一个事件驱动、非阻塞的I/O模型，使得它非常适合构建高性能的网络应用。Node.js基于ChromeV8引擎构建，能够执行JavaScript代码。npm（NodePa</div>
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<span class="text-muted">涛涛酱10086</span>
<a class="tag" taget="_blank" href="/search/node.js/1.htm">node.js</a><a class="tag" taget="_blank" href="/search/%E5%AD%A6%E4%B9%A0/1.htm">学习</a><a class="tag" taget="_blank" href="/search/node.js/1.htm">node.js</a>
<div>文件上传文件上传的方案：大文件上传：将大文件切分成较小的片段（通常称为分片或块），然后逐个上传这些分片。这种方法可以提高上传的稳定性，因为如果某个分片上传失败，只需要重新上传该分片而不需要重新上传整个文件。同时，分片上传还可以利用多个网络连接并行上传多个分片，提高上传速度断点续传：在上传过程中，如果网络中断或上传被中止，断点续传技术可以记录已成功上传的分片信息，以便在恢复上传时继续上传未完成的部分</div>
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<span class="text-muted">老三不说话、</span>
<a class="tag" taget="_blank" href="/search/uni-app/1.htm">uni-app</a><a class="tag" taget="_blank" href="/search/harmonyos/1.htm">harmonyos</a>
<div>一、开发前的准备工作开发鸿蒙App之前，我们需要做好充分的准备工作。首先是工具的安装与配置。Node.js的安装：推荐使用LTS版本的Node.js。可以前往Node.js的官方网站下载适合自己操作系统的安装包，如Windows用户根据自己的系统版本选择32位或64位版本。安装过程较为简单，只需按照安装向导一步步进行操作，同意许可协议，选择安装位置即可。安装完成后，可以使用命令行工具（如Power</div>
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<span class="text-muted">Jarvis Downey</span>
<a class="tag" taget="_blank" href="/search/JavaScript/1.htm">JavaScript</a><a class="tag" taget="_blank" href="/search/vue/1.htm">vue</a><a class="tag" taget="_blank" href="/search/vue.js/1.htm">vue.js</a><a class="tag" taget="_blank" href="/search/%E5%89%8D%E7%AB%AF/1.htm">前端</a><a class="tag" taget="_blank" href="/search/javascript/1.htm">javascript</a>
<div>Axios是一个基于Promise的HTTP客户端，用于浏览器和node.js，它提供了一种非常方便的方式来发送异步HTTP请求。在Vue2应用中，Axios可以帮助我们轻松地与后端API进行通信。本文将介绍如何在Vue2项目中引入Axios，并使用它来发起POST和GET请求。1.安装Axios首先，你需要在你的Vue项目中安装Axios。打开终端，切换到你的项目目录，然后运行以下命令：npmi</div>
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<a class="tag" taget="_blank" href="/search/sqlite/1.htm">sqlite</a><a class="tag" taget="_blank" href="/search/node.js/1.htm">node.js</a><a class="tag" taget="_blank" href="/search/%E6%95%B0%E6%8D%AE%E5%BA%93/1.htm">数据库</a>
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<a class="tag" taget="_blank" href="/search/Linux/1.htm">Linux</a><a class="tag" taget="_blank" href="/search/linux/1.htm">linux</a><a class="tag" taget="_blank" href="/search/centos/1.htm">centos</a><a class="tag" taget="_blank" href="/search/%E8%BF%90%E7%BB%B4/1.htm">运维</a>
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<span class="text-muted">acoolgiser</span>
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<div>花了两天半时间！！！终于解决了这个问题。。。故总结于此在node.js多进程项目中，程序直接run没问题，但debug时老提示端口占用。“Debuggerlisteningon[::]:25951”node.js调试时出现端口占用的问题，。出现的错误为“Error:listenEADDRI”，而且端口是动态变化的。错误如下：Debuggerlisteningon[::]:25951Error:li</div>
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<span class="text-muted">BigCat2013</span>
<a class="tag" taget="_blank" href="/search/mongodb/1.htm">mongodb</a><a class="tag" taget="_blank" href="/search/DB/1.htm">DB</a><a class="tag" taget="_blank" href="/search/%E9%AB%98%E5%B9%B6%E5%8F%91/1.htm">高并发</a><a class="tag" taget="_blank" href="/search/%E9%87%8D%E5%A4%8D%E6%95%B0%E6%8D%AE/1.htm">重复数据</a>
<div>最近项目用到 MongoDB , 主要是一些读取数据及改状态位的操作. 因为是结合了最近流行的 Storm进行大数据的分析处理，并将分析结果插入Vertica数据库，所以在多线程高并发的情境下, 会发现 Vertica 数据库中有部分重复的数据. 这到底是什么原因导致的呢？笔者开始也是一筹莫 展，重复去看 MongoDB 的 API , 终于有了新发现 ：
com.mongodb.DB 这个类有</div>
</li>
<li><a href="/article/295.htm"
title="c++ 用类模版实现链表(c++语言程序设计第四版示例代码)" target="_blank">c++ 用类模版实现链表(c++语言程序设计第四版示例代码)</a>
<span class="text-muted">CrazyMizzz</span>
<a class="tag" taget="_blank" href="/search/%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84/1.htm">数据结构</a><a class="tag" taget="_blank" href="/search/C%2B%2B/1.htm">C++</a>
<div>#include<iostream>
#include<cassert>
using namespace std;
template<class T>
class Node
{
private:
Node<T> * next;
public:
T data; </div>
</li>
<li><a href="/article/422.htm"
title="最近情况" target="_blank">最近情况</a>
<span class="text-muted">麦田的设计者</span>
<a class="tag" taget="_blank" href="/search/%E6%84%9F%E6%85%A8/1.htm">感慨</a><a class="tag" taget="_blank" href="/search/%E8%80%83%E8%AF%95/1.htm">考试</a><a class="tag" taget="_blank" href="/search/%E7%94%9F%E6%B4%BB/1.htm">生活</a>
<div> 在五月黄梅天的岁月里，一年两次的软考又要开始了。到目前为止，我已经考了多达三次的软考，最后的结果就是通过了初级考试（程序员）。人啊，就是不满足，考了初级就希望考中级，于是，这学期我就报考了中级，明天就要考试。感觉机会不大，期待奇迹发生吧。这个学期忙于练车，写项目，反正最后是一团糟。后天还要考试科目二。这个星期真的是很艰难的一周，希望能快点度过。
</div>
</li>
<li><a href="/article/549.htm"
title="linux系统中用pkill踢出在线登录用户" target="_blank">linux系统中用pkill踢出在线登录用户</a>
<span class="text-muted">被触发</span>
<a class="tag" taget="_blank" href="/search/linux/1.htm">linux</a>
<div>由于linux服务器允许多用户登录，公司很多人知道密码，工作造成一定的障碍所以需要有时踢出指定的用户
1/#who 查出当前有那些终端登录（用 w 命令更详细）
# who
root pts/0 2010-10-28 09:36 (192</div>
</li>
<li><a href="/article/676.htm"
title="仿QQ聊天第二版" target="_blank">仿QQ聊天第二版</a>
<span class="text-muted">肆无忌惮_</span>
<a class="tag" taget="_blank" href="/search/qq/1.htm">qq</a>
<div>在第一版之上的改进内容:
第一版链接:
http://479001499.iteye.com/admin/blogs/2100893
用map存起来号码对应的聊天窗口对象,解决私聊的时候所有消息发到一个窗口的问题.
增加ViewInfo类,这个是信息预览的窗口,如果是自己的信息,则可以进行编辑.
信息修改后上传至服务器再告诉所有用户,自己的窗口</div>
</li>
<li><a href="/article/803.htm"
title="java读取配置文件" target="_blank">java读取配置文件</a>
<span class="text-muted">知了ing</span>
<div>1，java读取.properties配置文件
InputStream in;
try {
in = test.class.getClassLoader().getResourceAsStream("config/ipnetOracle.properties");//配置文件的路径
Properties p = new Properties()</div>
</li>
<li><a href="/article/930.htm"
title="__attribute__ 你知多少？" target="_blank">__attribute__ 你知多少？</a>
<span class="text-muted">矮蛋蛋</span>
<a class="tag" taget="_blank" href="/search/C%2B%2B/1.htm">C++</a><a class="tag" taget="_blank" href="/search/gcc/1.htm">gcc</a>
<div>原文地址:
http://www.cnblogs.com/astwish/p/3460618.html
GNU C 的一大特色就是__attribute__ 机制。__attribute__ 可以设置函数属性（Function Attribute ）、变量属性（Variable Attribute ）和类型属性（Type Attribute ）。
__attribute__ 书写特征是：</div>
</li>
<li><a href="/article/1057.htm"
title="jsoup使用笔记" target="_blank">jsoup使用笔记</a>
<span class="text-muted">alleni123</span>
<a class="tag" taget="_blank" href="/search/java/1.htm">java</a><a class="tag" taget="_blank" href="/search/%E7%88%AC%E8%99%AB/1.htm">爬虫</a><a class="tag" taget="_blank" href="/search/JSoup/1.htm">JSoup</a>
<div><dependency>
<groupId>org.jsoup</groupId>
<artifactId>jsoup</artifactId>
<version>1.7.3</version>
</dependency>
2014/08/28
今天遇到这种形式， </div>
</li>
<li><a href="/article/1184.htm"
title="JAVA中的集合 Collectio 和Map的简单使用及方法" target="_blank">JAVA中的集合 Collectio 和Map的简单使用及方法</a>
<span class="text-muted">百合不是茶</span>
<a class="tag" taget="_blank" href="/search/list/1.htm">list</a><a class="tag" taget="_blank" href="/search/map/1.htm">map</a><a class="tag" taget="_blank" href="/search/set/1.htm">set</a>
<div> List ,set ,map的使用方法和区别
java容器类类库的用途是保存对象，并将其分为两个概念：
Collection集合：一个独立的序列，这些序列都服从一条或多条规则;List必须按顺序保存元素 ，set不能重复元素；Queue按照排队规则来确定对象产生的顺序（通常与他们被插入的</div>
</li>
<li><a href="/article/1311.htm"
title="杀LINUX的JOB进程" target="_blank">杀LINUX的JOB进程</a>
<span class="text-muted">bijian1013</span>
<a class="tag" taget="_blank" href="/search/linux/1.htm">linux</a><a class="tag" taget="_blank" href="/search/unix/1.htm">unix</a>
<div>今天发现数据库一个JOB一直在执行，都执行了好几个小时还在执行，所以想办法给删除掉
系统环境：
ORACLE 10G
Linux操作系统
操作步骤如下：
第一步.查询出来那个job在运行，找个对应的SID字段
select * from dba_jobs_running--找到job对应的sid
&n</div>
</li>
<li><a href="/article/1438.htm"
title="Spring AOP详解" target="_blank">Spring AOP详解</a>
<span class="text-muted">bijian1013</span>
<a class="tag" taget="_blank" href="/search/java/1.htm">java</a><a class="tag" taget="_blank" href="/search/spring/1.htm">spring</a><a class="tag" taget="_blank" href="/search/AOP/1.htm">AOP</a>
<div> 最近项目中遇到了以下几点需求，仔细思考之后，觉得采用AOP来解决。一方面是为了以更加灵活的方式来解决问题，另一方面是借此机会深入学习Spring AOP相关的内容。例如，以下需求不用AOP肯定也能解决，至于是否牵强附会，仁者见仁智者见智。
1.对部分函数的调用进行日志记录，用于观察特定问题在运行过程中的函数调用</div>
</li>
<li><a href="/article/1565.htm"
title="[Gson六]Gson类型适配器(TypeAdapter)" target="_blank">[Gson六]Gson类型适配器(TypeAdapter)</a>
<span class="text-muted">bit1129</span>
<a class="tag" taget="_blank" href="/search/Adapter/1.htm">Adapter</a>
<div>TypeAdapter的使用动机
Gson在序列化和反序列化时，默认情况下，是按照POJO类的字段属性名和JSON串键进行一一映射匹配，然后把JSON串的键对应的值转换成POJO相同字段对应的值，反之亦然，在这个过程中有一个JSON串Key对应的Value和对象之间如何转换(序列化/反序列化)的问题。
以Date为例，在序列化和反序列化时，Gson默认使用java.</div>
</li>
<li><a href="/article/1692.htm"
title="【spark八十七】给定Driver Program， 如何判断哪些代码在Driver运行，哪些代码在Worker上执行" target="_blank">【spark八十七】给定Driver Program， 如何判断哪些代码在Driver运行，哪些代码在Worker上执行</a>
<span class="text-muted">bit1129</span>
<a class="tag" taget="_blank" href="/search/driver/1.htm">driver</a>
<div>Driver Program是用户编写的提交给Spark集群执行的application，它包含两部分
作为驱动： Driver与Master、Worker协作完成application进程的启动、DAG划分、计算任务封装、计算任务分发到各个计算节点(Worker)、计算资源的分配等。
计算逻辑本身，当计算任务在Worker执行时，执行计算逻辑完成application的计算任务
</div>
</li>
<li><a href="/article/1819.htm"
title="nginx 经验总结" target="_blank">nginx 经验总结</a>
<span class="text-muted">ronin47</span>
<a class="tag" taget="_blank" href="/search/nginx+%E6%80%BB%E7%BB%93/1.htm">nginx 总结</a>
<div> 深感nginx的强大，只学了皮毛，把学下的记录。
获取Header 信息，一般是以$http_XX（ＸＸ是小写）
获取body,通过接口，再展开，根据Ｋ取Ｖ
获取uri,以$arg_XX
&n</div>
</li>
<li><a href="/article/1946.htm"
title="轩辕互动-1.求三个整数中第二大的数2.整型数组的平衡点" target="_blank">轩辕互动-1.求三个整数中第二大的数2.整型数组的平衡点</a>
<span class="text-muted">bylijinnan</span>
<a class="tag" taget="_blank" href="/search/%E6%95%B0%E7%BB%84/1.htm">数组</a>
<div>
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class ExoWeb {
public static void main(String[] args) {
ExoWeb ew=new ExoWeb();
System.out.pri</div>
</li>
<li><a href="/article/2073.htm"
title="Netty源码学习-Java-NIO-Reactor" target="_blank">Netty源码学习-Java-NIO-Reactor</a>
<span class="text-muted">bylijinnan</span>
<a class="tag" taget="_blank" href="/search/java/1.htm">java</a><a class="tag" taget="_blank" href="/search/%E5%A4%9A%E7%BA%BF%E7%A8%8B/1.htm">多线程</a><a class="tag" taget="_blank" href="/search/netty/1.htm">netty</a>
<div>Netty里面采用了NIO-based Reactor Pattern
了解这个模式对学习Netty非常有帮助
参考以下两篇文章：
http://jeewanthad.blogspot.com/2013/02/reactor-pattern-explained-part-1.html
http://gee.cs.oswego.edu/dl/cpjslides/nio.pdf
</div>
</li>
<li><a href="/article/2200.htm"
title="AOP通俗理解" target="_blank">AOP通俗理解</a>
<span class="text-muted">cngolon</span>
<a class="tag" taget="_blank" href="/search/spring/1.htm">spring</a><a class="tag" taget="_blank" href="/search/AOP/1.htm">AOP</a>
<div>1.我所知道的aop 初看aop,上来就是一大堆术语，而且还有个拉风的名字，面向切面编程，都说是OOP的一种有益补充等等。一下子让你不知所措，心想着：怪不得很多人都和 我说aop多难多难。当我看进去以后，我才发现：它就是一些java基础上的朴实无华的应用，包括ioc，包括许许多多这样的名词，都是万变不离其宗而 已。 2.为什么用aop&nb</div>
</li>
<li><a href="/article/2327.htm"
title="cursor variable 实例" target="_blank">cursor variable 实例</a>
<span class="text-muted">ctrain</span>
<a class="tag" taget="_blank" href="/search/variable/1.htm">variable</a>
<div>
create or replace procedure proc_test01
as
type emp_row is record(
empno emp.empno%type,
ename emp.ename%type,
job emp.job%type,
mgr emp.mgr%type,
hiberdate emp.hiredate%type,
sal emp.sal%t</div>
</li>
<li><a href="/article/2454.htm"
title="shell报bash: service: command not found解决方法" target="_blank">shell报bash: service: command not found解决方法</a>
<span class="text-muted">daizj</span>
<a class="tag" taget="_blank" href="/search/linux/1.htm">linux</a><a class="tag" taget="_blank" href="/search/shell/1.htm">shell</a><a class="tag" taget="_blank" href="/search/service/1.htm">service</a><a class="tag" taget="_blank" href="/search/jps/1.htm">jps</a>
<div>今天在执行一个脚本时，本来是想在脚本中启动hdfs和hive等程序，可以在执行到service hive-server start等启动服务的命令时会报错，最终解决方法记录一下：
脚本报错如下：
./olap_quick_intall.sh: line 57: service: command not found
./olap_quick_intall.sh: line 59</div>
</li>
<li><a href="/article/2581.htm"
title="40个迹象表明你还是PHP菜鸟" target="_blank">40个迹象表明你还是PHP菜鸟</a>
<span class="text-muted">dcj3sjt126com</span>
<a class="tag" taget="_blank" href="/search/%E8%AE%BE%E8%AE%A1%E6%A8%A1%E5%BC%8F/1.htm">设计模式</a><a class="tag" taget="_blank" href="/search/PHP/1.htm">PHP</a><a class="tag" taget="_blank" href="/search/%E6%AD%A3%E5%88%99%E8%A1%A8%E8%BE%BE%E5%BC%8F/1.htm">正则表达式</a><a class="tag" taget="_blank" href="/search/oop/1.htm">oop</a>
<div>你是PHP菜鸟，如果你：1. 不会利用如phpDoc 这样的工具来恰当地注释你的代码2. 对优秀的集成开发环境如Zend Studio 或Eclipse PDT 视而不见3. 从未用过任何形式的版本控制系统，如Subclipse4. 不采用某种编码与命名标准 ，以及通用约定，不能在项目开发周期里贯彻落实5. 不使用统一开发方式6. 不转换（或）也不验证某些输入或SQL查询串（译注：参考PHP相关函</div>
</li>
<li><a href="/article/2708.htm"
title="Android逐帧动画的实现" target="_blank">Android逐帧动画的实现</a>
<span class="text-muted">dcj3sjt126com</span>
<a class="tag" taget="_blank" href="/search/android/1.htm">android</a>
<div>一、代码实现：
private ImageView iv;
private AnimationDrawable ad;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout</div>
</li>
<li><a href="/article/2835.htm"
title="java远程调用linux的命令或者脚本" target="_blank">java远程调用linux的命令或者脚本</a>
<span class="text-muted">eksliang</span>
<a class="tag" taget="_blank" href="/search/linux/1.htm">linux</a><a class="tag" taget="_blank" href="/search/ganymed-ssh2/1.htm">ganymed-ssh2</a>
<div>转载请出自出处：
http://eksliang.iteye.com/blog/2105862
Java通过SSH2协议执行远程Shell脚本(ganymed-ssh2-build210.jar)
使用步骤如下：
1.导包
官网下载:
http://www.ganymed.ethz.ch/ssh2/
ma</div>
</li>
<li><a href="/article/2962.htm"
title="adb端口被占用问题" target="_blank">adb端口被占用问题</a>
<span class="text-muted">gqdy365</span>
<a class="tag" taget="_blank" href="/search/adb/1.htm">adb</a>
<div>最近重新安装的电脑，配置了新环境，老是出现：
adb server is out of date. killing...
ADB server didn't ACK
* failed to start daemon *
百度了一下，说是端口被占用，我开个eclipse，然后打开cmd，就提示这个，很烦人。
一个比较彻底的解决办法就是修改</div>
</li>
<li><a href="/article/3089.htm"
title="ASP.NET使用FileUpload上传文件" target="_blank">ASP.NET使用FileUpload上传文件</a>
<span class="text-muted">hvt</span>
<a class="tag" taget="_blank" href="/search/.net/1.htm">.net</a><a class="tag" taget="_blank" href="/search/C%23/1.htm">C#</a><a class="tag" taget="_blank" href="/search/hovertree/1.htm">hovertree</a><a class="tag" taget="_blank" href="/search/asp.net/1.htm">asp.net</a><a class="tag" taget="_blank" href="/search/webform/1.htm">webform</a>
<div>前台代码：
<asp:FileUpload ID="fuKeleyi" runat="server" />
<asp:Button ID="BtnUp" runat="server" onclick="BtnUp_Click" Text="上 传" /></div>
</li>
<li><a href="/article/3216.htm"
title="代码之谜（四）- 浮点数（从惊讶到思考）" target="_blank">代码之谜（四）- 浮点数（从惊讶到思考）</a>
<span class="text-muted">justjavac</span>
<a class="tag" taget="_blank" href="/search/%E6%B5%AE%E7%82%B9%E6%95%B0/1.htm">浮点数</a><a class="tag" taget="_blank" href="/search/%E7%B2%BE%E5%BA%A6/1.htm">精度</a><a class="tag" taget="_blank" href="/search/%E4%BB%A3%E7%A0%81%E4%B9%8B%E8%B0%9C/1.htm">代码之谜</a><a class="tag" taget="_blank" href="/search/IEEE/1.htm">IEEE</a>
<div>在『代码之谜』系列的前几篇文章中，很多次出现了浮点数。 浮点数在很多编程语言中被称为简单数据类型，其实，浮点数比起那些复杂数据类型（比如字符串）来说， 一点都不简单。
单单是说明 IEEE浮点数 就可以写一本书了，我将用几篇博文来简单的说说我所理解的浮点数，算是抛砖引玉吧。 一次面试
记得多年前我招聘 Java 程序员时的一次关于浮点数、二分法、编码的面试， 多年以后，他已经称为了一名很出色的</div>
</li>
<li><a href="/article/3343.htm"
title="数据结构随记_1" target="_blank">数据结构随记_1</a>
<span class="text-muted">lx.asymmetric</span>
<a class="tag" taget="_blank" href="/search/%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84/1.htm">数据结构</a><a class="tag" taget="_blank" href="/search/%E7%AC%94%E8%AE%B0/1.htm">笔记</a>
<div>第一章
1.数据结构包括数据的
逻辑结构、数据的物理/存储结构和数据的逻辑关系这三个方面的内容。 2.数据的存储结构可用四种基本的存储方法表示，它们分别是
顺序存储、链式存储 、索引存储 和 散列存储。 3.数据运算最常用的有五种，分别是
查找/检索、排序、插入、删除、修改。 4.算法主要有以下五个特性：
输入、输出、可行性、确定性和有穷性。 5.算法分析的</div>
</li>
<li><a href="/article/3470.htm"
title="linux的会话和进程组" target="_blank">linux的会话和进程组</a>
<span class="text-muted">网络接口</span>
<a class="tag" taget="_blank" href="/search/linux/1.htm">linux</a>
<div>会话： 一个或多个进程组。起于用户登录，终止于用户退出。此期间所有进程都属于这个会话期。会话首进程：调用setsid创建会话的进程1.规定组长进程不能调用setsid，因为调用setsid后，调用进程会成为新的进程组的组长进程.如何保证？ 先调用fork，然后终止父进程，此时由于子进程的进程组ID为父进程的进程组ID，而子进程的ID是重新分配的，所以保证子进程不会是进程组长，从而子进程可以调用se</div>
</li>
<li><a href="/article/3597.htm"
title="二维数组 元素的连续求解" target="_blank">二维数组 元素的连续求解</a>
<span class="text-muted">1140566087</span>
<a class="tag" taget="_blank" href="/search/%E4%BA%8C%E7%BB%B4%E6%95%B0%E7%BB%84/1.htm">二维数组</a><a class="tag" taget="_blank" href="/search/ACM/1.htm">ACM</a>
<div>import java.util.HashMap;
public class Title {
public static void main(String[] args){
f();
}
// 二位数组的应用
//12、二维数组中，哪一行或哪一列的连续存放的0的个数最多，是几个0。注意，是“连续”。
public static void f(){
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<li><a href="/article/3724.htm"
title="也谈什么时候Java比C++快" target="_blank">也谈什么时候Java比C++快</a>
<span class="text-muted">windshome</span>
<a class="tag" taget="_blank" href="/search/java/1.htm">java</a><a class="tag" taget="_blank" href="/search/C%2B%2B/1.htm">C++</a>
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刚打开iteye就看到这个标题“Java什么时候比C++快”，觉得很好笑。
你要比，就比同等水平的基础上的相比，笨蛋写得C代码和C++代码，去和高手写的Java代码比效率，有什么意义呢？
我是写密码算法的，深刻知道算法C和C++实现和Java实现之间的效率差，甚至也比对过C代码和汇编代码的效率差，计算机是个死的东西，再怎么优化，Java也就是和C</div>
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