/// <summary>
/// 下载媒体文件。
/// 如果下载成功，返回值的ErrMsg属性携带保存的文件全路径
/// </summary>
/// <param name="mediaId"></param>
/// <param name="filePath">
/// 保存下载的文件的本地文件名或目录(以\结尾)。
/// 如果为目录，则文件名为微信响应的文件名。
/// 如果文件已经存在，则会覆盖原文件。
/// </param>
/// <returns>如果成功，ErrMsg属性携带保存的文件全路径</returns>
public BasicResult Download(string mediaId, string filePath)
{
var param = new FormData
{
{"access_token", AccessToken},
{"media_id", mediaId}
};
var url = string.Format("{0}?{1}", DownLoadUrl, param.Format());
var request = HttpHelper.CreateRequest(url);
var response = request.GetResponse();
using (var stream = response.GetResponseStream())
{
var disposition = response.Headers["Content-disposition"];
if (string.IsNullOrEmpty(disposition))
{
var s = new StreamReader(stream, Encoding.UTF8).ReadToEnd();
return JsonConvert.DeserializeObject<BasicResult>(s);
}
filePath = filePath.EndsWith(@"\")
? string.Format("{0}{1}", filePath, Regex.Match(disposition, "(?<=filename\\s*=\\s*\\\"?)[^\\\"]+", RegexOptions.IgnoreCase))
: filePath;
var fs = new FileStream(filePath, FileMode.OpenOrCreate);
try
{
var buffer = new byte[128 * 1024]; //128K
int i;
while ((i = stream.Read(buffer, 0, buffer.Length)) > 0)
{
fs.Write(buffer, 0, i);
}
return BasicResult.GetSuccess(filePath);
}
finally
{
fs.Close();
}
}
}
