C#中POST数据和接收的几种方式（抛砖引玉）

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POST方式提交数据，一种众所周知的方式：

html页面中使用form表单提交，接收方式，使用Request.Form[""]或Request.QueryString[""]来获取。

这里介绍另外一种POST方式和接收方式，就是将整个数据作为加入到数据流中提交和接收

接收方式:

Stream s = System.Web.HttpContext.Current.Request.InputStream;
byte[] b = new byte[s.Length];
s.Read(b, , (int)s.Length);
return Encoding.UTF8.GetString(b);

只需要从input Stream中读取byte数据，然后转为string，再解析即可。如果要回复响应消息只需要用：Response.Write() 输出即可（和普通的页面输出一样）。

主动POST发送方式：

HttpWebRequest webrequest = (HttpWebRequest)HttpWebRequest.Create(url);
webrequest.Method = "post"; byte[] postdatabyte = Encoding.UTF8.GetBytes(postData);
webrequest.ContentLength = postdatabyte.Length;
Stream stream;
stream = webrequest.GetRequestStream();
stream.Write(postdatabyte, , postdatabyte.Length);
stream.Close(); using (var httpWebResponse = webrequest.GetResponse())
using (StreamReader responseStream = new StreamReader(httpWebResponse.GetResponseStream()))
{ String ret = responseStream.ReadToEnd(); T result = XmlDeserialize<T>(ret); return result;
}

使用HttpClient对象发送

public static string PostXmlResponse(string url, string xmlString) {
HttpContent httpContent = new StringContent(xmlString);
httpContent.Headers.ContentType = new MediaTypeHeaderValue("application/json");
HttpClient httpClient = new HttpClient(); HttpResponseMessage response = httpClient.PostAsync(url, httpContent).Result; if (response.IsSuccessStatusCode)
{
Task<string> t = response.Content.ReadAsStringAsync();
return t.Result;
}
return string.Empty;
}

从代码中可以看出仅仅是将字符串转为byte[] 类型，并加入到请求流中，进行请求即可达到POST效果，该种POST方式与上边所提到的接收方式相互配合使用。

下面一种方式是以键值对的方式主动POST传输的。

/// <summary>
/// 发起httpPost 请求，可以上传文件
/// </summary>
/// <param name="url">请求的地址</param>
/// <param name="files">文件</param>
/// <param name="input">表单数据</param>
/// <param name="endoding">编码</param>
/// <returns></returns>
public static string PostResponse(string url, UpLoadFile[] files, Dictionary<string, string> input, Encoding endoding)
{ string boundary = "----------------------------" + DateTime.Now.Ticks.ToString("x");
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.ContentType = "multipart/form-data; boundary=" + boundary;
request.Method = "POST";
request.KeepAlive = true;
//request.Credentials = CredentialCache.DefaultCredentials;
request.Expect = ""; MemoryStream stream = new MemoryStream(); byte[] line = Encoding.ASCII.GetBytes("--" + boundary + "\r\n");
byte[] enterER = Encoding.ASCII.GetBytes("\r\n");
////提交文件
if (files != null)
{
string fformat = "Content-Disposition:form-data; name=\"{0}\";filename=\"{1}\"\r\nContent-Type:{2}\r\n\r\n";
foreach (UpLoadFile file in files)
{ stream.Write(line, , line.Length); //项目分隔符
string s = string.Format(fformat, file.Name, file.FileName, file.Content_Type);
byte[] data = Encoding.UTF8.GetBytes(s);
stream.Write(data, , data.Length);
stream.Write(file.Data, , file.Data.Length);
stream.Write(enterER, , enterER.Length); //添加\r\n
}
} //提交文本字段
if (input != null)
{
string format = "--" + boundary + "\r\nContent-Disposition:form-data;name=\"{0}\"\r\n\r\n{1}\r\n"; //自带项目分隔符
foreach (string key in input.Keys)
{
string s = string.Format(format, key, input[key]);
byte[] data = Encoding.UTF8.GetBytes(s);
stream.Write(data, , data.Length);
} } byte[] foot_data = Encoding.UTF8.GetBytes("--" + boundary + "--\r\n"); //项目最后的分隔符字符串需要带上--
stream.Write(foot_data, , foot_data.Length); request.ContentLength = stream.Length;
Stream requestStream = request.GetRequestStream(); //写入请求数据
stream.Position = 0L;
stream.CopyTo(requestStream); //
stream.Close(); requestStream.Close(); try
{ HttpWebResponse response;
try
{
response = (HttpWebResponse)request.GetResponse(); try
{
using (var responseStream = response.GetResponseStream())
using (var mstream = new MemoryStream())
{
responseStream.CopyTo(mstream);
string message = endoding.GetString(mstream.ToArray());
return message;
}
}
catch (Exception ex)
{
throw ex;
}
}
catch (WebException ex)
{
//response = (HttpWebResponse)ex.Response; //if (response.StatusCode == HttpStatusCode.BadRequest)
//{
// using (Stream data = response.GetResponseStream())
// {
// using (StreamReader reader = new StreamReader(data))
// {
// string text = reader.ReadToEnd();
// Console.WriteLine(text);
// }
// }
//} throw ex;
} }
catch (Exception ex)
{
throw ex;
}
}

通过两种主动POST提交的代码可以看出，其主要区别在于发送前的数据格式 ContentType 的值。

下面列举几种常用的ContentType 值，并简述他们的区别

Content-Type 被指定为 application/x-www-form-urlencoded 时候，传输的数据格式需要如 title=test&sub%5B%5D=1&sub%5B%5D=2&sub%5B%5D=3 所示格式，才能正确解析

Content-Type 被指定为 multipart/form-data 时候，所需格式如下面代码块中所示

Content-Type:multipart/form-data; boundary=----WebKitFormBoundaryrGKCBY7qhFd3TrwA------WebKitFormBoundaryrGKCBY7qhFd3TrwAContent-Disposition: form-data; name="text"title------WebKitFormBoundaryrGKCBY7qhFd3TrwAContent-Disposition: form-data; name="file"; filename="chrome.png"Content-Type: image/pngPNG ... content of chrome.png ...------WebKitFormBoundaryrGKCBY7qhFd3TrwA--

Content-Type 也可以被指定为 application/json ，最终传输格式为 {"title":"test","sub":[1,2,3]} 至于如何接收本人未经尝试，但是可以肯定的讲使用文章开头所说的接收方式接收后转为string类型再

发序列化是可行的。

Content-Type指定为 text/xml ，传输的数据格式为

<?xml version="1.0"?>
<methodCall>
<methodName>examples.getStateName</methodName>
<params>
<param>
<value><i4></i4></value>
</param>
</params>
</methodCall>

此种方式，本人亦未经尝试，接受方式可以参考上文中 application/json 的接收方式。

由于xml的格式传输数据，使用相对较少，相信很多同学亦不知道如何将字符串解析为对象，下文将提供一种转换方式，供参考

XmlDocument doc = new XmlDocument();
doc.LoadXml(weixin);//读取xml字符串
XmlElement root = doc.DocumentElement; ExmlMsg xmlMsg = new ExmlMsg()
{
FromUserName = root.SelectSingleNode("FromUserName").InnerText,
ToUserName = root.SelectSingleNode("ToUserName").InnerText,
CreateTime = root.SelectSingleNode("CreateTime").InnerText,
MsgType = root.SelectSingleNode("MsgType").InnerText,
};
if (xmlMsg.MsgType.Trim().ToLower() == "text")
{
xmlMsg.Content = root.SelectSingleNode("Content").InnerText;
}
else if (xmlMsg.MsgType.Trim().ToLower() == "event")
{
xmlMsg.EventName = root.SelectSingleNode("Event").InnerText;
}
return xmlMsg;

private class ExmlMsg
{
/// <summary>
/// 本公众账号
/// </summary>
public string ToUserName { get; set; }
/// <summary>
/// 用户账号
/// </summary>
public string FromUserName { get; set; }
/// <summary>
/// 发送时间戳
/// </summary>
public string CreateTime { get; set; }
/// <summary>
/// 发送的文本内容
/// </summary>
public string Content { get; set; }
/// <summary>
/// 消息的类型
/// </summary>
public string MsgType { get; set; }
/// <summary>
/// 事件名称
/// </summary>
public string EventName { get; set; } }