jersey rest and csv response

Question

I have created a rest call that responds back with the CSV file using Jersey.

rest call code is:

@GET
@Path("/ReportWithoutADEStatus")
@Produces({ "application/ms-excel"})
public Response generateQurterlyReport(){
    QuarterlyLabelReport quartLabelReport = new QuarterlyLabelReport();
    String fileLoc=quartLabelReport.generateQurterlyLblRep(false);
    File file=new File(fileLoc);
    return Response.ok(fileLoc,"application/ms-excel")
            .header( "Content-Disposition","attachment;filename=QuarterlyReport_withoutADE.csv")
            .build();
}

The above code reads a csv file created in a temp location and responds that csv using rest call. This is perfectly working fine. But now the requirement has changed. stream the file content in memory and respond that in csv format from Rest API.
I have never done streaming to a file in memory and responding back the content in REST.

Can somebody help me with this?

Thanks in advance.

Answer 1

You need to use a StreamingResponse as your response entity. In my projects I've made a simple method to return on of these from a byte array. You just have to ready the file into a byte are first, then call this:

private StreamingOutput getOut(final byte[] excelBytes) {
    return new StreamingOutput() {
        @Override
        public void write(OutputStream out) throws IOException, WebApplicationException {
            out.write(excelBytes);
        }
    };
}

Then in your main method you would something like:

return Response.ok(getOut(byteArray)).build(); //add content-disp stuff here too if wanted