asp.net 模拟CURL调用微信公共平台API 上传下载多媒体文件接口

public class FormItem
{
public string Name { get; set; }
public ParamType ParamType { get; set; }
public string Value { get; set; }
}

public enum ParamType
{
///
/// 文本类型
///
Text,
///
/// 文件路径，需要全路径（例：C:\A.JPG)
///
File
}

public static class Funcs
{
public static string PostFormData(List list,string uri)
{
string boundary = "---------------------------" + DateTime.Now.Ticks.ToString("x");
//请求
WebRequest req = WebRequest.Create(uri);
req.Method = "POST";
req.ContentType = "multipart/form-data; boundary=" + boundary;
//组织表单数据
StringBuilder sb = new StringBuilder();
foreach (FormItem item in list)
{
switch (item.ParamType)
{
case ParamType.Text:
sb.Append("--" + boundary);
sb.Append("\r\n");
sb.Append("Content-Disposition: form-data; name="" + item.Name + """);
sb.Append("\r\n\r\n");
sb.Append(item.Value);
sb.Append("\r\n");
break;
case ParamType.File:
sb.Append("--" + boundary);
sb.Append("\r\n");
sb.Append("Content-Disposition: form-data; name="media"; filename=""+item.Value+""");
sb.Append("\r\n");
sb.Append("Content-Type: application/octet-stream");
sb.Append("\r\n\r\n");
break;
}
}
string head = sb.ToString();
//post字节总长度
long length = 0;
byte[] form_data = Encoding.UTF8.GetBytes(head);
//结尾
byte[] foot_data = Encoding.UTF8.GetBytes("\r\n--" + boundary + "--\r\n");
List fileList = list.Where(f => f.ParamType == ParamType.File).ToList();
length = form_data.Length + foot_data.Length;
foreach (FormItem fi in fileList)
{
FileStream fileStream = new FileStream(fi.Value, FileMode.Open, FileAccess.Read);
length += fileStream.Length;
fileStream.Close();
}
req.ContentLength = length;

Stream requestStream = req.GetRequestStream();
//发送表单参数
requestStream.Write(form_data, 0, form_data.Length);
foreach (FormItem fd in fileList)
{
FileStream fileStream = new FileStream(fd.Value, FileMode.Open, FileAccess.Read);
//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;
}
///
/// 从URL地址下载文件到本地磁盘
///
/// 本地磁盘地址
/// URL网址
///
public static string SaveFileFromUrl(string FileName, string Url)
{
WebResponse response = null;
Stream stream = null;
try
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url);
response = request.GetResponse();
stream = response.GetResponseStream();

if (!response.ContentType.ToLower().StartsWith("text/"))
{
SaveBinaryFile(response, FileName);
}
else
{
StreamReader sr = new StreamReader(stream, System.Text.Encoding.UTF8);
return sr.ReadToEnd();
}

}
catch (Exception err)
{
return err.ToString();
}
return "complete";
}
///
/// 将二进制文件保存到磁盘
///
/// 将二进制文件保存到磁盘
// 将二进制文件保存到磁盘
private static bool SaveBinaryFile(WebResponse response, string FileName)
{
bool Value = true;
byte[] buffer = new byte[1024];

try
{
if (File.Exists(FileName))
File.Delete(FileName);
Stream outStream = System.IO.File.Create(FileName);
Stream inStream = response.GetResponseStream();

int l;
do
{
l = inStream.Read(buffer, 0, buffer.Length);
if (l > 0)
outStream.Write(buffer, 0, l);
}
while (l > 0);

outStream.Close();
inStream.Close();
}
catch
{
Value = false;
}
return Value;
}
}

//新建一个form表单项，就是需要提交哪些字段和数据的列表
List list = new List();
//添加微信接口上的access_token参数，注意，access_token是有过期时间的，代码中的access_token肯定过期了，获取access_token的地址请点击我，需要有自己的服务号才会有的
list.Add(new FormItem() { Name = "access_token", ParamType = ParamType.Text, Value = "MlfTORyg_dRTuiQThmKUxVVkK7q_SMEd0y9GwBmj6NJw3E0J2jVnC3RxgdO1Yjog2QD4DDxhdqEkZaklR7czq8sSbW4mnhM7n9-5lIIymVGkrBAv2nnnktUyYcuYTMs2SYtp-pn6IWEtTpsFVlUFZQ" });
//添加FORM表单中这条数据的类型，目前只做了两种，一种是文本，一种是文件
list.Add(new FormItem() { Name = "type", Value = "image", ParamType = ParamType.Text });
//添加Form表单中文件的路径，路径必须是基于硬盘的绝对路径
list.Add(new FormItem() { Name = "media", Value = @"d:\1.jpg", ParamType = ParamType.File });
//通过Funcs静态类中的PostFormData方法，将表单数据发送至http://file.api.weixin.qq.com/cgi-bin/media/upload腾讯上传下载文件接口
string result = Funcs.PostFormData(list, "http://file.api.weixin.qq.com/cgi-bin/media/upload");
//获取返回值，并取出的结果中的media_id，注意，有可能返回的是腾讯的错误代码，请自行判断
System.Web.Script.Serialization.JavaScriptSerializer jss = new System.Web.Script.Serialization.JavaScriptSerializer();
var mydata=jss.Deserialize(result);
//通过Funcs静态类中的SaveFileFromUrl方法，将指定微信media_id的文件下载到本机
var saveResult=Funcs.SaveFileFromUrl(@"d:\lee.jpg", "http://file.api.weixin.qq.com/cgi-bin/media/get?access_token=MlfTORyg_dRTuiQThmKUxVVkK7q_SMEd0y9GwBmj6NJw3E0J2jVnC3RxgdO1Yjog2QD4DDxhdqEkZaklR7czq8sSbW4mnhM7n9-5lIIymVGkrBAv2nnnktUyYcuYTMs2SYtp-pn6IWEtTpsFVlUFZQ&media_id=" + mydata["media_id"].ToString());