.net的http请求

.net的http来爬数据还是相对简单的，下面介绍一下http的post请求。

一、代码

        public static string HttpPost(string formUrl, string formData)
        {
            try
            {
                //注意提交的编码 这边是需要改变的 这边默认的是Default：系统当前编码
                byte[] postData = System.Text.Encoding.UTF8.GetBytes(formData);

                // 设置提交的相关参数 
                HttpWebRequest request = WebRequest.Create(formUrl) as HttpWebRequest;
                Encoding myEncoding = Encoding.UTF8;
                request.Method = "POST";
                request.KeepAlive = false;
                request.AllowAutoRedirect = true;
                request.ContentType = "application/x-www-form-urlencoded";
                request.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 2.0.50727; .NET CLR  3.0.04506.648; .NET CLR 3.5.21022; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)";

                request.ContentLength = postData.Length;

                // 提交请求数据 
                System.IO.Stream outputStream = request.GetRequestStream();
                outputStream.Write(postData, 0, postData.Length);
                outputStream.Close();

                HttpWebResponse response;
                Stream responseStream;
                StreamReader reader;
                string srcString;
                response = request.GetResponse() as HttpWebResponse;
                responseStream = response.GetResponseStream();
                //reader = new System.IO.StreamReader(responseStream, Encoding.GetEncoding("UTF-8"));
                reader = new System.IO.StreamReader(responseStream, Encoding.GetEncoding("GB2312"));
                srcString = reader.ReadToEnd();
                string result = srcString;   //返回值赋值
                reader.Close();
                return result;
            }
            catch
            {
                return "error";
            }
        }

1) 调用方法HttpPost(string formUrl, string formData)分别是请求的URL和post请求的body参数数据

2）reader = new System.IO.StreamReader(responseStream, Encoding.GetEncoding("GB2312"));看看请求返回的数据是什么编码格式的，

可以对应改为GB2312或者UTF-8。

三、返回的数据可以进行解析

1）一般根据p或者table的id来对应获取想要的数据

2）如果获取的p里面嵌套很多p或者table时,也可以对应补充结束符或/table>

例如你获取到的数据如下：

<p id="test2">test2</p>
<p id="test3">&nbsp;</p>

<p id="test">test
<p id="test2">test2</p>

的结束符