SmartGWT〜DSRequest下载文件

Question

I am writing a server side class in smartGWT that fetches a record from a table and downloads a binary blob as a file from the database. The goal is to get the binary file attachment to download to local computer.

I was told that I could use DSRequest.getUploadedFile(attachment) to download the file but looking into it, it looks as though this method does not get an uploaded file from the database to download but gets a file to upload to the database.

Is there a way that I can get a file from the database and return it to the user as a download in server side code? We know we can do this in client side code but we would like to be able to do it on the server.

Here is how I am getting the record that contains the file I want to send to the user.

DSRequest dsReq = new DSRequest("table", "fetch");
dsReq.setCriteria("criteria", processFlowData.getVariableMap().get("critera"));

DataSource ds = dsReq.getDataSource();
DSResponse dsResp = ds.execute(dsReq);

if (dsResp.getStatus() < 0) {
    //Handle Errors
} else {
    if (!dsResp.getRecord().isEmpty()) {
        //Download File Here
    }
}

I am using Eclipse Kepler, SmartGWT, Java EE.

Answer 1

you could do something like this:

public static void downloadFile(DSRequest dsRequest, RPCManager rpcManager, HttpServletResponse servletResponse) throws Exception {
    rpcManager.doCustomResponse();
    ServletOutputStream outputStream = servletResponse.getOutputStream();
    servletResponse.addHeader("Content-disposition", "attachment; filename=test.pdf");
    servletResponse.setContentType("application/x-www-form-urlencoded");
    OutputStream responseOutputStream = servletResponse.getOutputStream();
    // write file to responseOutputStream
    responseOutputStream.flush();
    responseOutputStream.close();
}