download.java

response.setContentType("multipart/form-data");
response.setHeader("Content-Disposition", "attachment;fileName=" + attachId);

//<form id="sampleForm" name="sampleForm" enctype="multipart/form-data" action="" method="post">

if("jpg".equals(dataObject.getString("FILEFORMAT").toLowerCase())){
  response.setContentType("image/jpeg");
} else if("jpeg".equals(dataObject.getString("FILEFORMAT").toLowerCase())){
  response.setContentType("image/jpeg");
} else if("gif".equals(dataObject.getString("FILEFORMAT").toLowerCase())){
  response.setContentType("image/gif");
} else if("png".equals(dataObject.getString("FILEFORMAT").toLowerCase())){
  response.setContentType("image/png");
} else if("pdf".equals(dataObject.getString("FILEFORMAT").toLowerCase())){
  response.setContentType("application/pdf");
} else if("doc".equals(dataObject.getString("FILEFORMAT").toLowerCase())){
  response.setContentType("application/msword");
} else if("docx".equals(dataObject.getString("FILEFORMAT").toLowerCase())){
  response.setContentType("application/vnd.openxmlformats-officedocument.wordprocessingml.document");
} else if("xls".equals(dataObject.getString("FILEFORMAT").toLowerCase())){
  response.setContentType("application/vnd.ms-excel");
} else if("xlsx".equals(dataObject.getString("FILEFORMAT").toLowerCase())){
  response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
} else if("odt".equals(dataObject.getString("FILEFORMAT").toLowerCase())){
  response.setContentType("application/vnd.oasis.opendocument.text");
} else if("ods".equals(dataObject.getString("FILEFORMAT").toLowerCase())){
  response.setContentType("application/vnd.oasis.opendocument.spreadsheet");
}