error uploading file HTTP Client & RESTful server - rest

Question

I'm trying to create a HTTP Client to upload a file following this example: http://java.dzone.com/articles/file-upload-apache-httpclient
When I run the application to upload the file on my RESTFul service, I get:
HTTP ERROR 500
Problem accessing /file/upload. Reason:
Server ErrorCaused by:java.lang.NullPointerException
at com.nice.rest.UploadFileService.uploadFile(UploadFileService.java:33)
...
Where line 33 is:
public class UploadFileService {
#POST
#Path("/upload")
#Consumes(MediaType.MULTIPART_FORM_DATA)
public Response uploadFile(
#FormDataParam("file") InputStream uploadedInputStream,
#FormDataParam("file") FormDataContentDisposition fileDetail) {
//line 33: String uploadedFileLocation = "/mnt/folder/"+ fileDetail.getFileName();
System.out.println("uploadedFileLocation : "+uploadedFileLocation);
// save it
writeToFile(uploadedInputStream, uploadedFileLocation);
String output = "200 OK<br />" + uploadedFileLocation;
return Response.status(200).entity(output).build();
}
Surprisingly, when I upload a file using a html form it works fine:
form action="http://X.X.X.X:8080/file/upload" method="post" enctype="multipart/form-data"
What's wrong?
thanks!!

Answer 1

When you build your multi-part entity, make sure that the #FormDataParam annotation value contains the name of the part within the multipart.
It looks like the part you're looking for doesn't exist hence the NullPointerException.
Please post your client code if possible showing how you construct the multi-part entity