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How to overwrite existing file during file download rather than create a new file

I am using GWT to do file upload, question, how to just overwrite existing file if exists rather create a new file, ex, file(1).doc. Here is my server side code.
protected void service(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
try {
String modelPath = AutoConstants.PREFIX + "/var/models/";
File file = new File(modelPath + "/" + MODEL_NAME);
if (file.exists()) {
ServletOutputStream out = response.getOutputStream();
DataInputStream in = new DataInputStream(new FileInputStream(
file));
response.setHeader("Pragma", "public");
response.setHeader("Cache-Control",
"must-revalidate, post-check=0, pre-check=0");
response.setHeader("Content-Length",
String.valueOf(file.length()));
response.setHeader("Content-Disposition",
"attachment; fileName=\"" + MODEL_NAME + "\"");
int i = 0;
int BUFSIZE = 8192;
byte[] bbuf = new byte[BUFSIZE];
while ((in != null) && ((i = in.read(bbuf)) != -1)) {
out.write(bbuf, 0, i);
}
in.close();
out.flush();
}
} catch (Exception e) {
logger.error("Exception.getModel", e);
throw new ServletException(e.getMessage());
}
}

Spring OutputStream - download pptx with IE

I use this Java code to download files from a web application:
#RequestMapping(value = "/filedownloads/filedownload/{userid}/{projectid}/{documentfileid}/{version}/", method = RequestMethod.GET)
public void filesDownload(final #PathVariable("userid") String userId, final #PathVariable("projectid") String projectId,
final #PathVariable("documentfileid") String documentFileId, final #PathVariable("version") String version,
final HttpServletResponse response) throws IOException, BusinessException {
...
final String fileName = "filename=" + documentFile.getFileName();
final InputStream is = new FileInputStream(filePath);
response.setHeader("Content-Disposition", "inline; " + fileName);
IOUtils.copy(is, response.getOutputStream());
response.flushBuffer();
}
if I will download a pptx- file I get the following IE- page:
What I want to do is to open the downloaded file in Powerpoint.
My question now would be if there is a header setting in order to open this file with the right application (in this case Powerpoint)

Simply try to set the Content Type header properly which is application/vnd.openxmlformats-officedocument.presentationml.presentation in case a pptx, as next:
response.setContentType(
"application/vnd.openxmlformats-officedocument.presentationml.presentation"
);
response.setHeader(
"Content-Disposition",
String.format("inline; filename=\"%s\"", documentFile.getFileName())
);
response.setContentLength((int) new File(filePath).length());
Here is the list of mime types corresponding to Office 2007 documents.

Here is a little sample code from a Spring MVC Controller:
#RequestMapping("/ppt")
public void downloadPpt(HttpServletRequest request, HttpServletResponse response) throws IOException {
Resource resource = new ClassPathResource("Presentation1.pptx");
InputStream resourceInputStream = resource.getInputStream();
response.setHeader("Content-Disposition", "attachment; filename=\"Presentation1.pptx\"");
response.setContentLengthLong(resource.contentLength());
byte[] buffer = new byte[1024];
int len;
while ((len = resourceInputStream.read(buffer)) != -1) {
response.getOutputStream().write(buffer, 0, len);
}
}
By setting the Content-Disposition to attachment, you're telling the browser to download this file as an attachment and by supplying the correct file name with extension, you're telling the Operating System to use whatever application the user normally uses to open a file of this type. In this case it will be MS Power Point.
This way you can get away with not knowing exactly what version of Power Point the file was created with.

I have tested code in IE-11 its work fine. See below code i.e
#RequestMapping(value = "/downloadfile", method = RequestMethod.GET)
#ResponseBody
public void downloadfile(HttpServletRequest request, HttpServletResponse response) throws Exception {
ServletOutputStream servletOutputStream = null;
try {
response.setContentType("application/octet-stream");
response.setHeader("Content-Disposition", "attachment; filename=downloadppt.pptx");
byte[] ppt = downloadFile();
servletOutputStream = response.getOutputStream();
servletOutputStream.write(ppt);
} catch (Exception e) {
throw e;
} finally {
servletOutputStream.flush();
servletOutputStream.close();
}
}
Generate bytes from saved pptx file.
public byte[] downloadFile() throws IOException {
InputStream inputStream = new FileInputStream(new File("e:/testppt.pptx"));
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
// Transfer bytes from source to destination
byte[] buf = new byte[1024];
int len;
while ((len = inputStream.read(buf)) > 0) {
byteArrayOutputStream.write(buf, 0, len);
}
inputStream.close();
byteArrayOutputStream.close();
return byteArrayOutputStream.toByteArray();
}
That's it, you are able to download pptx file. Hope code help you, if you have any query or doubt then we can discuss or if any suggestions. Thank you

How to download file in browser using spring mvc?

I have file on the server & that I want to download on my machine using browser. But I am not getting an option from browser to download the file.
My code is
JSP
<div id="jqgrid">
<table id="grid"></table>
<div id="pager"></div>
</div>
JS
jq("#grid").jqGrid({
....
onCellSelect: function(rowid, index, contents, event) {
...
var fileName = jQuery("#grid").jqGrid('getCell',rowid,'fileName');
$scope.downloadFile(fileName);
}
});
$scope.downloadFile = function(fileName) {
$http({
url: "logreport/downLoadFile",
method: "GET",
params: {"fileName": fileName}
});
};
Controller
#RequestMapping(value = "/downLoadFile", method = RequestMethod.GET)
public void downLoadFile(HttpServletRequest request, HttpServletResponse response) {
try {
String fileName = request.getParameter("fileName");
File file = new File(filePath +"//"+fileName);
InputStream in = new BufferedInputStream(new FileInputStream(file));
response.setContentType("application/xlsx");
response.setHeader("Content-Disposition", "attachment; filename="+fileName+".xlsx");
ServletOutputStream out = response.getOutputStream();
IOUtils.copy(in, out);
response.flushBuffer();
} catch (Exception e) {
e.printStackTrace();
}
}
I am not getting any exception but not sure why browser dialog is not opening to download the file. Also where is it exactly downloading the file?

#SotiriosDelimanolis was right. File download is not possible using ajax request.
Simply use 'window.location'.
$scope.downloadFile = function(fileName) {
window.location.href = 'logreport/downLoadFile?fileName=asdad1';
};

I didn't have enough credit to give a comment so wiritting here.. Thanks user1298426. I was strugling like anything for this. I was trying with AJAX. With window.location.href, I can download file in browser...
MY javascript code is as follows:
jQuery('#exportToZip').click(function() {
window.location.href = '*****';
});
*****: is the url mapping that I have in controller.
#RequestMapping(value = "/****")
#ResponseBody
public void downloadRequesthandler(HttpServletRequest request,HttpServletResponse response) {
String status;
try {
filedownloader.doGet(request, response);
} catch (ServletException e) {
status="servlet Exception occured";
e.printStackTrace();
} catch (IOException e) {
status="IO Exception occured";
e.printStackTrace();
}
//return status;
}
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
ServletContext context = request.getServletContext();
// construct the complete absolute path of the file
File downloadFile = new File(filePath);
System.out.println("downloadFile path: "+ filePath);
FileInputStream inputStream = new FileInputStream(downloadFile);
// get MIME type of the file
String mimeType = context.getMimeType(fullPath);
if (mimeType == null) {
// set to binary type if MIME mapping not found
mimeType = "application/octet-stream";
}
System.out.println("MIME type: " + mimeType);
response.setContentLength((int) downloadFile.length());
// set headers for the response
String headerKey = "Content-Disposition";
String headerValue = String.format("attachment; filename=\"%s\"",downloadFile.getName());
response.setHeader(headerKey, headerValue);
OutputStream outStream = response.getOutputStream();
byte[] buffer = new byte[BUFFER_SIZE];
System.out.println("buffer: "+ buffer.length);
int bytesRead = -1;
// write bytes read from the input stream into the output stream
//be carefull in this step. "writebeyondcontentlength" and "response already committed" error is very common here
while ((bytesRead = inputStream.read(buffer))!=-1 ) {
outStream.write(buffer, 0, bytesRead);
}
inputStream.close();
outStream.close();
}
Trying to download file with ajax is a blunder....
cheers......

Instead of using IOUtils copy method
ServletOutputStream out = response.getOutputStream();
IOUtils.copy(in, out);
You can use following :
ServletOutputStream out = response.getOutputStream();
byte[] bytes = IOUtils.toByteArray(in);
out.write(bytes);
out.close();
out.flush();
Hope this will work.

file download pop up is not coming

Wrote a simple code to download a file from file system but still not getting download pop up hence file is not downloading ,not even throwing any error .Please help me out.Following is my code written on controller side.
#RequestMapping(value = "download", method=RequestMethod.POST)
public #ResponseBody void download(HttpServletRequest request, HttpServletResponse response){
String fileName="/home/test/Testing.xlsx";
PrintWriter out=null;
try{
System.out.println(fileName.substring(fileName.lastIndexOf('/')+1)+"fileName");
response.setContentType("application/vnd.ms-excel");
response.setHeader("Cache-Control", "must-revalidate");
response.setHeader( "Pragma", "public" );
response.setHeader("Content-Disposition", "attachment; filename=" + fileName.substring(fileName.lastIndexOf('/')+1) );
out = response.getWriter();
int i;
FileInputStream inputStream = new FileInputStream(fileName);
while ((i = inputStream.read()) != -1) {
out.write(i);
}
inputStream.close();
out.close();
}
catch(Exception e){
System.out.println(e);
}
}

here mistake was POST method, we should not use post method instead we should always use GET method while writing program for download.
#RequestMapping(value = "download", method=RequestMethod.GET)
public #ResponseBody void download(HttpServletRequest request, HttpServletResponse response){
String fileName="/home/test/Testing.xlsx";
PrintWriter out=null;
try{
System.out.println(fileName.substring(fileName.lastIndexOf('/')+1)+"fileName");
response.setContentType("application/vnd.ms-excel");
response.setHeader("Cache-Control", "must-revalidate");
response.setHeader( "Pragma", "public" );
response.setHeader("Content-Disposition", "attachment; filename=" + fileName.substring(fileName.lastIndexOf('/')+1) );
out = response.getWriter();
int i;
FileInputStream inputStream = new FileInputStream(fileName);
while ((i = inputStream.read()) != -1) {
out.write(i);
}
inputStream.close();
out.close();
}
catch(Exception e){
System.out.println(e);
}
}

export content to a text file using java with save dialog

i have a result set which has got some values, i want to export the data which is there in result set as a text file with the save dialog.
how to do this in java?.
I have done the above requirement for excel and java like the following.
response.setContentType("application/vnd.ms-excel");
response.setHeader("Content-disposition", "attachment; filename=\"" + reportName + ".xls\"");
and
response.setHeader("Content-disposition", "attachment; filename=\"" + reportName + ".pdf\"");
response.setContentType("application/pdf");
UPDATE :
if(exportTo.equals("text")){
response.setContentType("text/plain");
response.setHeader("Content-disposition", "attachment; filename=\"" + reportName + ".txt\"");
try {
} catch (Exception e) {
// TODO: handle exception
}
}
in this
in try block how to set the contents which are avilable from resultset to a output stream and make it available.

the only difference is this :
response.setContentType("text/plain");
You can see a full example here ( http://www.mkyong.com/servlet/servlet-code-to-download-text-file-from-website-java/ )
UPDATE
This is a demo that I have developed and tested and works perfectly fine:
public class ServletDownloadDemo extends HttpServlet {
private static final int BYTES_DOWNLOAD = 1024;
public void init(ServletConfig config) throws ServletException {
super.init(config);
}
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException,
IOException {
response.setContentType("text/plain");
response.setHeader("Content-Disposition", "attachment;filename=downloadname.txt");
String s = "Test\n\nText file contects!!";
InputStream input = new ByteArrayInputStream(s.getBytes("UTF8"));
int read = 0;
byte[] bytes = new byte[BYTES_DOWNLOAD];
OutputStream os = response.getOutputStream();
while ((read = input.read(bytes)) != -1) {
os.write(bytes, 0, read);
}
os.flush();
os.close();
}
}
It downloads a text file named downloadname.txt with the contents of String s.
UPDATE 2
String s = "";
while (rs.next()) {
s += rs.getString("column_name");
}
if (exportTo.equals("text")) {
response.setContentType("text/plain");
response.setHeader("Content-Disposition", "attachment;filename=downloadname.txt");
try {
InputStream input = new ByteArrayInputStream(s.getBytes("UTF8"));
int read = 0;
byte[] bytes = new byte[BYTES_DOWNLOAD];
OutputStream os = response.getOutputStream();
//data form resultset
while ((read = input.read(bytes)) != -1) {
os.write(bytes, 0, read);
}
os.flush();
os.close();
} catch (Exception e) {
// TODO: handle exception
}
}
You have to populate your ResultSet and place what you need in String s. That's all.