[英]Get Content-Disposition parameters
如何獲取使用 WebClient 從 WebAPI 控制器返回的 Content-Disposition 參數?
WebApi 控制器
[Route("api/mycontroller/GetFile/{fileId}")]
public HttpResponseMessage GetFile(int fileId)
{
try
{
var file = GetSomeFile(fileId)
HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK);
response.Content = new StreamContent(new MemoryStream(file));
response.Content.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment");
response.Content.Headers.ContentDisposition.FileName = file.FileOriginalName;
/********* Parameter *************/
response.Content.Headers.ContentDisposition.Parameters.Add(new NameValueHeaderValue("MyParameter", "MyValue"));
return response;
}
catch(Exception ex)
{
return Request.CreateErrorResponse(HttpStatusCode.InternalServerError, ex);
}
}
客戶
void DownloadFile()
{
WebClient wc = new WebClient();
wc.DownloadDataCompleted += wc_DownloadDataCompleted;
wc.DownloadDataAsync(new Uri("api/mycontroller/GetFile/18"));
}
void wc_DownloadDataCompleted(object sender, DownloadDataCompletedEventArgs e)
{
WebClient wc=sender as WebClient;
// Try to extract the filename from the Content-Disposition header
if (!String.IsNullOrEmpty(wc.ResponseHeaders["Content-Disposition"]))
{
string fileName = wc.ResponseHeaders["Content-Disposition"].Substring(wc.ResponseHeaders["Content-Disposition"].IndexOf("filename=") + 10).Replace("\"", ""); //FileName ok
/****** How do I get "MyParameter"? **********/
}
var data = e.Result; //File OK
}
我正在從 WebApi 控制器返回一個文件,我在響應內容標頭中附加了文件名,但我還想返回一個附加值。
在客戶端中,我可以獲取文件名,但是如何獲取附加參數?
如果您使用 .NET 4.5 或更高版本,請考慮使用System.Net.Mime.ContentDisposition類:
string cpString = wc.ResponseHeaders["Content-Disposition"];
ContentDisposition contentDisposition = new ContentDisposition(cpString);
string filename = contentDisposition.FileName;
StringDictionary parameters = contentDisposition.Parameters;
// You have got parameters now
編輯:
否則,您需要根據它的規范解析 Content-Disposition 標頭。
這是一個執行解析的簡單類,接近規范:
class ContentDisposition {
private static readonly Regex regex = new Regex(
"^([^;]+);(?:\\s*([^=]+)=((?<q>\"?)[^\"]*\\k<q>);?)*$",
RegexOptions.Compiled
);
private readonly string fileName;
private readonly StringDictionary parameters;
private readonly string type;
public ContentDisposition(string s) {
if (string.IsNullOrEmpty(s)) {
throw new ArgumentNullException("s");
}
Match match = regex.Match(s);
if (!match.Success) {
throw new FormatException("input is not a valid content-disposition string.");
}
var typeGroup = match.Groups[1];
var nameGroup = match.Groups[2];
var valueGroup = match.Groups[3];
int groupCount = match.Groups.Count;
int paramCount = nameGroup.Captures.Count;
this.type = typeGroup.Value;
this.parameters = new StringDictionary();
for (int i = 0; i < paramCount; i++ ) {
string name = nameGroup.Captures[i].Value;
string value = valueGroup.Captures[i].Value;
if (name.Equals("filename", StringComparison.InvariantCultureIgnoreCase)) {
this.fileName = value;
}
else {
this.parameters.Add(name, value);
}
}
}
public string FileName {
get {
return this.fileName;
}
}
public StringDictionary Parameters {
get {
return this.parameters;
}
}
public string Type {
get {
return this.type;
}
}
}
然后你可以這樣使用它:
static void Main() {
string text = "attachment; filename=\"fname.ext\"; param1=\"A\"; param2=\"A\";";
var cp = new ContentDisposition(text);
Console.WriteLine("FileName:" + cp.FileName);
foreach (DictionaryEntry param in cp.Parameters) {
Console.WriteLine("{0} = {1}", param.Key, param.Value);
}
}
// Output:
// FileName:"fname.ext"
// param1 = "A"
// param2 = "A"
使用此類時唯一應該考慮的是它不處理沒有雙引號的參數(或文件名)。
編輯2:
它現在可以處理沒有引號的文件名。
您可以使用以下框架代碼解析出內容配置:
var content = "attachment; filename=myfile.csv";
var disposition = ContentDispositionHeaderValue.Parse(content);
然后從處置實例中取出碎片。
disposition.FileName
disposition.DispositionType
價值就在那里,我只需要提取它:
Content-Disposition 標頭的返回方式如下:
Content-Disposition = attachment; filename="C:\team.jpg"; MyParameter=MyValue
所以我只是使用了一些字符串操作來獲取值:
void wc_DownloadDataCompleted(object sender, DownloadDataCompletedEventArgs e)
{
WebClient wc=sender as WebClient;
// Try to extract the filename from the Content-Disposition header
if (!String.IsNullOrEmpty(wc.ResponseHeaders["Content-Disposition"]))
{
string[] values = wc.ResponseHeaders["Content-Disposition"].Split(';');
string fileName = values.Single(v => v.Contains("filename"))
.Replace("filename=","")
.Replace("\"","");
/********** HERE IS THE PARAMETER ********/
string myParameter = values.Single(v => v.Contains("MyParameter"))
.Replace("MyParameter=", "")
.Replace("\"", "");
}
var data = e.Result; //File ok
}
正如@Mehrzad Chehraz 所說,您可以使用新的ContentDisposition
類。
using System.Net.Mime;
// file1 is a HttpResponseMessage
FileName = new ContentDisposition(file1.Content.Headers.ContentDisposition.ToString()).FileName
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