C#.Net 4.8 框架如何将 API POST 调用中的查询字符串参数从标题更改为正文并在新选项卡中打开 PDF

如何解决C#.Net 4.8 框架如何将 API POST 调用中的查询字符串参数从标题更改为正文并在新选项卡中打开 PDF

[OP 评论/编辑]

我以为我已经完成了，但是在让这段代码工作后我保存了 PDF（非常感谢@User9938）。我可以保存PDF，但是当我打开文件时它没有打开，而是给出了“编码不正确的错误”......这是创建文件的代码（但不允许我保存它）！！有什么想法吗？

using (WebClient wc = new WebClient())
{
    //wc.Headers.Clear(); // Did not help
    wc.Headers.Add("Content-Type","application/xml");
    wc.Encoding = System.Text.Encoding.UTF8;
            
    //var data = wc.UploadString(URI,QS1);
    //Worked with ASCII & UTF8,but UTF8 is far superior and will save you pain if you have any international symbols (non USA letters)
    Byte[] buffer =  wc.UploadData(URI,"POST",System.Text.Encoding.UTF8.GetBytes(QS1)); 
    //Byte [] buffer = wc.UploadValues(api.BaseURI,myCol);
    if (buffer != null)
    {
        Response.ContentType = "application/pdf";
        Response.AddHeader("content-length",buffer.Length.ToString());
        Response.BinaryWrite(buffer);
    }
}

尝试重新打开 PDF 时出现编码错误（保存后）。

[结束 OP 评论/编辑]

我的 C#（.NET Framework 4.8 代码）API 调用从 URI 返回 PDF。

公司更新了他们的 API，现在我必须在正文中传递参数（而不是查询字符串）。这是当前的“POST”版本，可在新的浏览器选项卡中打开 PDF。如何在正文中传递参数（而不是查询字符串）？这个完美的解决方案需要大量的挖掘才能使其工作，并且不适用于新系统。

    using (WebClient wc = new WebClient())
    {
        WebClient client = new WebClient();
        Byte[] buffer = client.DownloadData(https://destinationAPI.com/Request?A=Works&B=In&C=OldVersion);
        if (buffer != null)
        {
            Response.ContentType = "application/pdf";
            Response.AddHeader("content-length",buffer.Length.ToString());
            Response.BinaryWrite(buffer);
        }
    }

我的尝试：（我在失败的行旁边放了注释。）感谢@user9938 的评论，我尝试了这个 this 的各种版本，但仍然出现 415 错误。

string QS1 = "A=this&B=is&c=EasyOnceYouGetTheRightAnswer";
Uri URI = "https://Mypost.com/RequestMyPDF";
string strURI = "https://Mypost.com/RequestMyPDF";

using (WebClient wc = new WebClient())
            {
                //These 3 attempts get a 415 Error
                //Byte[] buffer =  wc.UploadData(URI,System.Text.Encoding.ASCII.GetBytes(QS1)); //415 Error
                //Byte[] buffer = wc.UploadData(URI,System.Text.Encoding.UTF8.GetBytes(QS1));//415 Error
                Byte[] buffer = wc.UploadData(strURI,System.Text.Encoding.UTF8.GetBytes(QS1));//415 Error
                if (buffer != null)
                {
                    Response.ContentType = "application/pdf";
                    Response.AddHeader("content-length",buffer.Length.ToString());
                    Response.BinaryWrite(buffer);
                }
            }

另一个尝试（原始尝试）我有这段代码将数据拉入流阅读器，但“文本/纯文本”的“上下文类型”有效（“应用程序/pdf”返回415错误）。如果我可以将streamreader变成byte[]，我想我可以使用上面的代码在新窗口中输出我的PDF。

try
{
    System.Net.WebRequest req = System.Net.WebRequest.Create(URI);
    //req.ContentType = "application/pdf" //This generates a 415 Error
    req.ContentType = "text/plain"; //This returns data,but I don't think it will work with a PDF.
    req.Method = "POST";
    //We need to count how many bytes we're sending. Post'ed Faked Forms should be name=value&
    byte[] bytes = System.Text.Encoding.ASCII.GetBytes(Parameters);
    req.ContentLength = bytes.Length;
    System.IO.Stream os = req.GetRequestStream();
    os.Write(bytes,bytes.Length); //Push it out there
    os.Close();
    System.Net.WebResponse resp = req.GetResponse();
    if (resp == null) return null;
            
    System.IO.StreamReader sr = new System.IO.StreamReader(resp.GetResponseStream());
    //READ to PDF and post in new window

    // Use ANSI encoding -also known as Encoding.GetEncoding(1252)??
    Encoding objEncoding = Encoding.Default;

    //StreamReader objSR = new StreamReader(sr.ReadToEnd().Trim(),objEncoding);
            
    //I want to open the pdf in a new tab,this is just an attempt to get ito to work... 
    //This creates an EMPTY PDF 
    StreamWriter objSW = new StreamWriter(@"c:\temp\Destination123.PDF",false,objEncoding);
    objSW.Write(sr.ReadToEnd().Trim());
    objSW.Close();
   
    //Byte[] buffer = ?? How to convert StreamWriter to BYTE!?!// (Old code was "Byte[] buffer = client.DownloadData(api.URI);")
    //if (buffer != null)
    //{
    //    Response.ContentType = "application/pdf";
    //    Response.AddHeader("content-length",buffer.Length.ToString());
    //    Response.BinaryWrite(buffer);
    //}
            
    return "Have we a PDF?!?!";
}
catch (Exception ex)
{
    return  ex.Message;
}

我对最后一个 415 错误的堆栈跟踪：

[WebException：远程服务器返回错误：(415) 不支持的媒体类型。] System.Net.WebClient.UploadDataInternal(Uri地址，String方法，Byte[]数据，WebRequest&请求)+317 System.Net.WebClient.UploadData(Uri地址，String方法，Byte[]数据)+160 System.Net.WebClient.UploadData(String address,String method,Byte[] data) +38 MyApp.Controllers.StatementsController.GetIndividualPDF(List1 model) +5328 lambda_method(Closure,ControllerBase,Object[] ) +103 System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller,Object[] parameters) +14 System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext,IDictionary2 个参数) +157 System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext,ActionDescriptor actionDescriptor,IDictionary2 parameters) +27 System.Web.Mvc.Async.AsyncControllerActionInvoker.<BeginInvokeSynchronousActionMethod>b__39(IAsyncResult asyncResult,ActionInvocation innerInvokeState) +22 System.Web.Mvc.Async.WrappedAsyncResult2.CallEndDelegate(IAsyncResult asyncResult) +29 System.Web.Mvc.Async.WrappedAsyncResultBase1.End() +49 System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) +32 System.Web.Mvc.Async.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() +50 System.Web.Mvc.Async.<>c__DisplayClass48.<InvokeActionMethodFilterAsynchronouslyRecursive>b__41() +228 System.Web.Mvc.Async.<>c__DisplayClass33.<BeginInvokeActionMethodWithFilters>b__32(IAsyncResult asyncResult) +10 System.Web.Mvc.Async.WrappedAsyncResult1.CallEndDelegate(IAsyncResult asyncResult) +10 System.Web.Mvc.Async.WrappedAsyncResultBase1.End() +49 System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) +34 System.Web.Mvc.Async.<>c__DisplayClass2b.<BeginInvokeAction>b__1c() +26 System.Web.Mvc.Async.<>c__DisplayClass21.<BeginInvokeAction>b__1e(IAsyncResult asyncResult) +100 System.Web.Mvc.Async.WrappedAsyncResult1.CallEndDelegate(IAsyncResult asyncResult) +10 System.Web.Mvc.Async.WrappedAsyncResultBase1.End() +49 System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +27 System.Web.Mvc.Controller.<BeginExecuteCore>b__1d(IAsyncResult asyncResult,ExecuteCoreState innerState) +13 System.Web.Mvc.Async.WrappedAsyncVoid1.CallEndDelegate(IAsyncResult asyncResult) +29 System.Web.Mvc.Async.WrappedAsyncResultBase1.End() +49 System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +36 System.Web.Mvc.Controller.<BeginExecute>b__15(IAsyncResult asyncResult,Controller controller) +12 System.Web.Mvc.Async.WrappedAsyncVoid1.CallEndDelegate(IAsyncResult asyncResult) +22 System.Web.Mvc.Async.WrappedAsyncResultBase1.End() +49 System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +26 System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +10 System.Web.Mvc.MvcHandler.<BeginProcessRequest>b__5(IAsyncResult asyncResult,ProcessRequestState innerState) +21 System.Web.Mvc.Async.WrappedAsyncVoid1.CallEndDelegate(IAsyncResult asyncResult) +29 System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49 System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +28 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult 结果) +9 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9836613 System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step) +50 System.Web.HttpApplication.ExecuteStep(IExecutionStep step,Boolean&completedSynchronously) +163

解决方法

！！！下面的代码创建了 PDF，它看起来很完美。我可以保存 PDF，但是当我尝试重新打开保存的文件时，出现以下编码错误！！

希望这可以为其他人省去一些麻烦。请参阅@User9938 对 OP 的评论，他对我有很大帮助并为我节省了很多时间。谢谢！坦率地说，现在我的标题是正确的，我的其他一些尝试也可能有效。我把它们留了下来，以免其他人不得不逐个查找。：

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