通过HTTP模拟GET或POST请求，提交数据到服务端获取响应，比较常见些；但如上传文件到服务端，使用html form当然简单了，而因环境所限有时需要使用模拟方法去提交有附件(文件上传)的表单。我们暂且不说如何去模拟数据，通过一个简单的form看看当请求发生时，客户端提交了什么样的数据给服务端。
下面是一个简单的html form，两个文本输入框，一个文件上传(这里我选择一张图片)，注意有文件上传的form的enctype属性。
html form
1
<
form
action
="sql.aspx"
method
="post"
enctype
="multipart/form-data"
>
2 < input id ="Text1" name ="content" type ="text" />< br />
3 < input id ="Text2" name ="uploadImg" type ="text" />< br />
4 < input id ="File1" type ="file" name ="image0" />< br />
5 < input id ="Submit1" type ="submit" value ="submit" />
6 </ form >
2 < input id ="Text1" name ="content" type ="text" />< br />
3 < input id ="Text2" name ="uploadImg" type ="text" />< br />
4 < input id ="File1" type ="file" name ="image0" />< br />
5 < input id ="Submit1" type ="submit" value ="submit" />
6 </ form >
为了查看表单提交时，向服务端post了什么数据，这里我使用Fiddler来查看。Fiddler确实是个不错的工具，注意当url主机地址是localhost时Fiddler捕获不到，需要再localhost后加一点(.)即可，打开Fiddler，浏览带上面form的page，输入数据提交，此时在Fiddler中可看到post的数据了。下面是一部份数据的截图。
分析其中的数据不难得出，一个表单中的数据域(input type="text")对应的格式为
-----------------------------7da119c1004a6
Content-Disposition: form-data; name="content"
this is a txt value
Content-Disposition: form-data; name="content"
this is a txt value
一个文件(input type="file")对应的格式为(通常为表单最后一个参数)
-----------------------------7da119c1004a6
Content-Disposition: form-data; name="image0"; filename="E:\CAI\875.jpg"
Content-Type: image/pjpeg
Content-Disposition: form-data; name="image0"; filename="E:\CAI\875.jpg"
Content-Type: image/pjpeg
[文件内容]
结尾处是-----------------------------7da119c1004a6--
有了上面的数据做参考，按照其格式组织数据，post到服务端，同样可以达到html form提交的效果。要特别注意其格式：如回车换行，差一个都可能得不到正确的响应，还有请求的Content-Length一定计算对。下面是一个参考：
代码
public
string
POSTfile(
string
v1,
string
v2,
string
file)
{
string boundary = " --------------------------- " + DateTime.Now.Ticks.ToString( " x " );
// 请求
WebRequest req = WebRequest.Create( @" http://localhost.:4944/WebSite1/getfile.aspx " );
req.Method = " POST " ;
req.ContentType = " multipart/form-data; boundary= " + boundary;
// 组织表单数据
StringBuilder sb = new StringBuilder();
sb.Append( " -- " + boundary);
sb.Append( " \r\n " );
sb.Append( " Content-Disposition: form-data; name=\ " content\ "" );
sb.Append( " \r\n\r\n " );
sb.Append(v1);
sb.Append( " \r\n " );
sb.Append( " -- " + boundary);
sb.Append( " \r\n " );
sb.Append( " Content-Disposition: form-data; name=\ " uploadImg\ "" );
sb.Append( " \r\n\r\n " );
sb.Append( " v2 " );
sb.Append( " \r\n " );
sb.Append( " -- " + boundary);
sb.Append( " \r\n " );
sb.Append( " Content-Disposition: form-data; name=\ " image0\ " ; filename=\ " e:\\a.jpg\ "" );
sb.Append( " \r\n " );
sb.Append( " Content-Type: image/pjpeg " );
sb.Append( " \r\n\r\n " );
string head = sb.ToString();
byte [] form_data = Encoding.UTF8.GetBytes(head);
// 结尾
byte [] foot_data = Encoding.UTF8.GetBytes( " \r\n-- " + boundary + " --\r\n " );
// 文件
FileStream fileStream = new FileStream(file, FileMode.Open, FileAccess.Read);
// post总长度
long length = form_data.Length + fileStream.Length + foot_data.Length;
req.ContentLength = length;
Stream requestStream = req.GetRequestStream();
// 发送表单参数
requestStream.Write(form_data, 0 , form_data.Length);
// 文件内容
byte [] buffer = new Byte[ checked (( uint )Math.Min( 4096 , ( int )fileStream.Length))];
int bytesRead = 0 ;
while ((bytesRead = fileStream.Read(buffer, 0 , buffer.Length)) != 0 )
requestStream.Write(buffer, 0 , bytesRead);
// 结尾
requestStream.Write(foot_data, 0 , foot_data.Length);
requestStream.Close();
// 响应
WebResponse pos = req.GetResponse();
StreamReader sr = new StreamReader(pos.GetResponseStream(), Encoding.UTF8);
string html = sr.ReadToEnd().Trim();
sr.Close();
if (pos != null )
{
pos.Close();
pos = null ;
}
if (req != null )
{
req = null ;
}
return html;
}
{
string boundary = " --------------------------- " + DateTime.Now.Ticks.ToString( " x " );
// 请求
WebRequest req = WebRequest.Create( @" http://localhost.:4944/WebSite1/getfile.aspx " );
req.Method = " POST " ;
req.ContentType = " multipart/form-data; boundary= " + boundary;
// 组织表单数据
StringBuilder sb = new StringBuilder();
sb.Append( " -- " + boundary);
sb.Append( " \r\n " );
sb.Append( " Content-Disposition: form-data; name=\ " content\ "" );
sb.Append( " \r\n\r\n " );
sb.Append(v1);
sb.Append( " \r\n " );
sb.Append( " -- " + boundary);
sb.Append( " \r\n " );
sb.Append( " Content-Disposition: form-data; name=\ " uploadImg\ "" );
sb.Append( " \r\n\r\n " );
sb.Append( " v2 " );
sb.Append( " \r\n " );
sb.Append( " -- " + boundary);
sb.Append( " \r\n " );
sb.Append( " Content-Disposition: form-data; name=\ " image0\ " ; filename=\ " e:\\a.jpg\ "" );
sb.Append( " \r\n " );
sb.Append( " Content-Type: image/pjpeg " );
sb.Append( " \r\n\r\n " );
string head = sb.ToString();
byte [] form_data = Encoding.UTF8.GetBytes(head);
// 结尾
byte [] foot_data = Encoding.UTF8.GetBytes( " \r\n-- " + boundary + " --\r\n " );
// 文件
FileStream fileStream = new FileStream(file, FileMode.Open, FileAccess.Read);
// post总长度
long length = form_data.Length + fileStream.Length + foot_data.Length;
req.ContentLength = length;
Stream requestStream = req.GetRequestStream();
// 发送表单参数
requestStream.Write(form_data, 0 , form_data.Length);
// 文件内容
byte [] buffer = new Byte[ checked (( uint )Math.Min( 4096 , ( int )fileStream.Length))];
int bytesRead = 0 ;
while ((bytesRead = fileStream.Read(buffer, 0 , buffer.Length)) != 0 )
requestStream.Write(buffer, 0 , bytesRead);
// 结尾
requestStream.Write(foot_data, 0 , foot_data.Length);
requestStream.Close();
// 响应
WebResponse pos = req.GetResponse();
StreamReader sr = new StreamReader(pos.GetResponseStream(), Encoding.UTF8);
string html = sr.ReadToEnd().Trim();
sr.Close();
if (pos != null )
{
pos.Close();
pos = null ;
}
if (req != null )
{
req = null ;
}
return html;
}
