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。
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
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
[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：
publicstring 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; }
//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; }