Download file from Liferay custom portlet

downloadFileLiferay.java

	private void downloadFile(ResourceRequest resourceRequest, ResourceResponse resourceResponse, String siteName) {
		try {
			File file = new File("${filePath}");
			
			InputStream in = new FileInputStream(file);
			
			HttpServletResponse httpRes = PortalUtil.getHttpServletResponse(resourceResponse);
			HttpServletRequest httpReq = PortalUtil.getHttpServletRequest(resourceRequest);
			ServletResponseUtil.sendFile(httpReq, httpRes, file.getName(), in, "application/download");
			
			in.close();
			
			FileUtil.delete(file);
		} catch (IOException e) {
			e.printStackTrace();
		}
	}