Dynamic file download without saving file in the server

Question

I am using Apache POI libraries to do some operation on multiple excel files.

I'm trying to download the excel report without storing it somewhere in the server.

I am using Struts 2 which needs the file fed into a InputStream while POI Workbook needs a OutputStream to write the data into.

Any help would be great

Answer 1

Since you already know you need a Stream result:

I am using Struts 2 which needs the file fed into a InputStream

// With Getter
private InputStream inputStream;

and you already know how to create an Excel with POI:

POI Workbook needs a OutputStream to write the data into.

public String execute(){

    // stuff 

    ByteArrayOutputStream baos = new ByteArrayOutputStream();

    // fill the OutputStream with the Excel content
    workbook.write(baos);

then the only missing piece is how to convert the POI's OutputStream into the Struts2 Stream result's InputStream. And this is easier than the rest..:

    // Create an Input Stream from the bytes extracted by the OutputStream
    inputStream = new ByteArrayInputStream(baos.toByteArray());

    return SUCCESS;
}