如何阅读C＃中的pdf并将文件返回给用户？

Question

我有一个C＃，剑道MVC，剃刀项目。用户点击Kendo网格中的一行，触发change事件，该事件对控制器进行api调用，该控制器读取pdf文件并将其返回给用户下载。我已经用csv文件完成了这项工作，并且工作正常，但是使用pdf时出现错误。有人可以告诉我为什么这个代码不适用于pdf？

Javascript语言，查看

window.location = "/api/WoApi/GetPDF/1?pdf=" + JSON.stringify(ID); 

C＃中的控制器

[HttpGet] 
public System.Net.WebResponse GetPDF(string pdf) 
{ 
    System.Net.WebRequest request = System.Net.WebRequest.Create("C:\\inetpub\\wwwroot\\Projects\\Attachments\\Invoice_2424.pdf"); 
    System.Net.WebResponse response = request.GetResponse(); 

    return response; 
} 

错误消息

> <Error> 
<Message>An error has occurred.</Message> 
<ExceptionMessage> 
The 'ObjectContent`1' type failed to serialize the response body for content type 'application/xml; charset=utf-8'. 
</ExceptionMessage> 
<ExceptionType>System.InvalidOperationException</ExceptionType> 
<StackTrace/> 
<InnerException> 
<Message>An error has occurred.</Message> 
<ExceptionMessage> 
Type 'System.Net.FileWebResponse' with data contract name 'FileWebResponse:http://schemas.datacontract.org/2004/07/System.Net' is not expected. Consider using a DataContractResolver if you are using DataContractSerializer or add any types not known statically to the list of known types - for example, by using the KnownTypeAttribute attribute or by adding them to the list of known types passed to the serializer. 
</ExceptionMessage> 
<ExceptionType> 
System.Runtime.Serialization.SerializationException 
</ExceptionType> 
<StackTrace> 
at System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeAndVerifyType(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, Boolean verifyKnownType, RuntimeTypeHandle declaredTypeHandle, Type declaredType) at System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeWithXsiTypeAtTopLevel(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, RuntimeTypeHandle originalDeclaredTypeHandle, Type graphType) at System.Runtime.Serialization.DataContractSerializer.InternalWriteObjectContent(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver) at System.Runtime.Serialization.DataContractSerializer.InternalWriteObject(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver) at System.Runtime.Serialization.XmlObjectSerializer.WriteObjectHandleExceptions(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver) at System.Runtime.Serialization.DataContractSerializer.WriteObject(XmlWriter writer, Object graph) at System.Net.Http.Formatting.XmlMediaTypeFormatter.<>c__DisplayClass7.<WriteToStreamAsync>b__6() at System.Threading.Tasks.TaskHelpers.RunSynchronously(Action action, CancellationToken token) 
</StackTrace> 
</InnerException> 
</Error> 

**更新＃1 **

我得到了下面的代码返回一个文件，但我仍然得到同样的错误消息：

string file = "C:\\inetpub\\wwwroot\\Projects\\Attachments\\Invoice_2424.pdf"; 
var test = new System.Web.Mvc.FilePathResult(file, "application/pdf"); 
return test; 

错误消息：

Error> 
<Message>An error has occurred.</Message> 
<ExceptionMessage> 
The 'ObjectContent`1' type failed to serialize the response body for content type 'application/xml; charset=utf-8'. 
</ExceptionMessage> 
<ExceptionType>System.InvalidOperationException</ExceptionType> 
<StackTrace/> 
<InnerException> 
<Message>An error has occurred.</Message> 
<ExceptionMessage> 
Type 'System.Web.Mvc.FilePathResult' cannot be serialized. Consider marking it with the DataContractAttribute attribute, and marking all of its members you want serialized with the DataMemberAttribute attribute. If the type is a collection, consider marking it with the CollectionDataContractAttribute. See the Microsoft .NET Framework documentation for other supported types. 
</ExceptionMessage> 
<ExceptionType> 
System.Runtime.Serialization.InvalidDataContractException 
</ExceptionType> 
<StackTrace> 
at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.ThrowInvalidDataContractException(String message, Type type) at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.CreateDataContract(Int32 id, RuntimeTypeHandle typeHandle, Type type) at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.GetDataContractSkipValidation(Int32 id, RuntimeTypeHandle typeHandle, Type type) at System.Runtime.Serialization.DataContractSerializer.GetDataContract(DataContract declaredTypeContract, Type declaredType, Type objectType) at System.Runtime.Serialization.DataContractSerializer.InternalWriteObjectContent(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver) at System.Runtime.Serialization.DataContractSerializer.InternalWriteObject(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver) at System.Runtime.Serialization.XmlObjectSerializer.WriteObjectHandleExceptions(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver) at System.Runtime.Serialization.DataContractSerializer.WriteObject(XmlWriter writer, Object graph) at System.Net.Http.Formatting.XmlMediaTypeFormatter.<>c__DisplayClass7.<WriteToStreamAsync>b__6() at System.Threading.Tasks.TaskHelpers.RunSynchronously(Action action, CancellationToken token) 
</StackTrace> 
</InnerException> 
</Error> 

Answer 1

CSV文件可能会被工作，因为它是基于文本格式，但PDF不是。

看起来你正在使用的网络API，

尝试这种方式，

[HttpGet] 
public HttpResponseMessage Generate() 
{ 

    var stream = new FileStream("C:\\inetpub\\wwwroot\\Projects\\Attachments\\Invoice_2424.pdf", FileMode.Open); 

    var result = new HttpResponseMessage(HttpStatusCode.OK) 
    { 
     Content = new ByteArrayContent(stream.ToArray()) 
    }; 
    result.Content.Headers.ContentDisposition = 
     new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment") 
    { 
     FileName = "fileName.pdf" 
    }; 
    result.Content.Headers.ContentType = 
     new MediaTypeHeaderValue("application/octet-stream"); 

    return result; 
} 

Answer 2

您也可以尝试返回只是一个文件，指定用正确的MIME类型的URL。

[HttpGet] 
public ActionResult GetPDF(string pdf) 
{ 
    string file = "C:\\inetpub\\wwwroot\\Projects\\Attachments\\Invoice_2424.pdf"; 

    return File(file, "application/pdf"); 
}