I have a Struts2 action in the server side for file downloading.
<action name="download" class="com.xxx.DownAction">
<result name="success" type="stream">
<param name="contentType">text/plain</param>
<param name="inputName">imageStream</param>
<param name="contentDisposition">attachment;filename={fileName}</param>
<param name="bufferSize">1024</param>
</result>
</action>
However when I call the action using the jQuery:
$.post(
"/download.action",{
para1:value1,
para2:value2
....
},function(data){
console.info(data);
}
);
in Firebug I see the data is retrieved with the Binary stream. I wonder how to open the file downloading window with which the user can save the file locally?
2019 modern browsers update
This is the approach I'd now recommend with a few caveats:
A relatively modern browser is required
If the file is expected to be very large you should likely do something similar to the original approach (iframe and cookie) because some of the below operations could likely consume system memory at least as large as the file being downloaded and/or other interesting CPU side effects.
fetch('https://jsonplaceholder.typicode.com/todos/1')
.then(resp => resp.blob())
.then(blob => {
const url = window.URL.createObjectURL(blob);
const a = document.createElement('a');
a.style.display = 'none';
a.href = url;
// the filename you want
a.download = 'todo-1.json';
document.body.appendChild(a);
a.click();
window.URL.revokeObjectURL(url);
alert('your file has downloaded!'); // or you know, something with better UX...
})
.catch(() => alert('oh no!'));
2012 Original jQuery/iframe/Cookie based approach
Bluish is completely right about this, you can't do it through Ajax because JavaScript cannot save files directly to a user's computer (out of security concerns). Unfortunately pointing the main window's URL at your file download means you have little control over what the user experience is when a file download occurs.
I created jQuery File Download which allows for an "Ajax like" experience with file downloads complete with OnSuccess and OnFailure callbacks to provide for a better user experience. Take a look at my blog post on the common problem that the plugin solves and some ways to use it and also a demo of jQuery File Download in action. Here is the source
Here is a simple use case demo using the plugin source with promises. The demo page includes many other, 'better UX' examples as well.
$.fileDownload('some/file.pdf')
.done(function () { alert('File download a success!'); })
.fail(function () { alert('File download failed!'); });
Depending on what browsers you need to support you may be able to use https://github.com/eligrey/FileSaver.js/ which allows more explicit control than the IFRAME method jQuery File Download uses.
Noone posted this #Pekka's solution... so I'll post it. It can help someone.
You don't need to do this through Ajax. Just use
window.location="download.action?para1=value1...."
You can with HTML5
NB: The file data returned MUST be base64 encoded because you cannot JSON encode binary data
In my AJAX response I have a data structure that looks like this:
{
result: 'OK',
download: {
mimetype: string(mimetype in the form 'major/minor'),
filename: string(the name of the file to download),
data: base64(the binary data as base64 to download)
}
}
That means that I can do the following to save a file via AJAX
var a = document.createElement('a');
if (window.URL && window.Blob && ('download' in a) && window.atob) {
// Do it the HTML5 compliant way
var blob = base64ToBlob(result.download.data, result.download.mimetype);
var url = window.URL.createObjectURL(blob);
a.href = url;
a.download = result.download.filename;
a.click();
window.URL.revokeObjectURL(url);
}
The function base64ToBlob was taken from here and must be used in compliance with this function
function base64ToBlob(base64, mimetype, slicesize) {
if (!window.atob || !window.Uint8Array) {
// The current browser doesn't have the atob function. Cannot continue
return null;
}
mimetype = mimetype || '';
slicesize = slicesize || 512;
var bytechars = atob(base64);
var bytearrays = [];
for (var offset = 0; offset < bytechars.length; offset += slicesize) {
var slice = bytechars.slice(offset, offset + slicesize);
var bytenums = new Array(slice.length);
for (var i = 0; i < slice.length; i++) {
bytenums[i] = slice.charCodeAt(i);
}
var bytearray = new Uint8Array(bytenums);
bytearrays[bytearrays.length] = bytearray;
}
return new Blob(bytearrays, {type: mimetype});
};
This is good if your server is dumping filedata to be saved. However, I've not quite worked out how one would implement a HTML4 fallback
The simple way to make the browser downloads a file is to make the request like that:
function downloadFile(urlToSend) {
var req = new XMLHttpRequest();
req.open("GET", urlToSend, true);
req.responseType = "blob";
req.onload = function (event) {
var blob = req.response;
var fileName = req.getResponseHeader("fileName") //if you have the fileName header available
var link=document.createElement('a');
link.href=window.URL.createObjectURL(blob);
link.download=fileName;
link.click();
};
req.send();
}
This opens the browser download pop up.
1. Framework agnostic: Servlet downloading file as attachment
<!-- with JS -->
<a href="javascript:window.location='downloadServlet?param1=value1'">
download
</a>
<!-- without JS -->
<a href="downloadServlet?param1=value1" >download</a>
2. Struts2 Framework: Action downloading file as attachment
<!-- with JS -->
<a href="javascript:window.location='downloadAction.action?param1=value1'">
download
</a>
<!-- without JS -->
<a href="downloadAction.action?param1=value1" >download</a>
It would be better to use <s:a> tag pointing with OGNL to an URL created with <s:url> tag:
<!-- without JS, with Struts tags: THE RIGHT WAY -->
<s:url action="downloadAction.action" var="url">
<s:param name="param1">value1</s:param>
</s:ulr>
<s:a href="%{url}" >download</s:a>
In the above cases, you need to write the Content-Disposition header to the response, specifying that the file needs to be downloaded (attachment) and not opened by the browser (inline). You need to specify the Content Type too, and you may want to add the file name and length (to help the browser drawing a realistic progressbar).
For example, when downloading a ZIP:
response.setContentType("application/zip");
response.addHeader("Content-Disposition",
"attachment; filename=\"name of my file.zip\"");
response.setHeader("Content-Length", myFile.length()); // or myByte[].length...
With Struts2 (unless you are using the Action as a Servlet, an hack for direct streaming, for example), you don't need to directly write anything to the response; simply using the Stream result type and configuring it in struts.xml will work: EXAMPLE
<result name="success" type="stream">
<param name="contentType">application/zip</param>
<param name="contentDisposition">attachment;filename="${fileName}"</param>
<param name="contentLength">${fileLength}</param>
</result>
3. Framework agnostic (/ Struts2 framework): Servlet(/Action) opening file inside the browser
If you want to open the file inside the browser, instead of downloading it, the Content-disposition must be set to inline, but the target can't be the current window location; you must target a new window created by javascript, an <iframe> in the page, or a new window created on-the-fly with the "discussed" target="_blank":
<!-- From a parent page into an IFrame without javascript -->
<a href="downloadServlet?param1=value1" target="iFrameName">
download
</a>
<!-- In a new window without javascript -->
<a href="downloadServlet?param1=value1" target="_blank">
download
</a>
<!-- In a new window with javascript -->
<a href="javascript:window.open('downloadServlet?param1=value1');" >
download
</a>
I have created little function as workaround solution (inspired by #JohnCulviner plugin):
// creates iframe and form in it with hidden field,
// then submit form with provided data
// url - form url
// data - data to form field
// input_name - form hidden input name
function ajax_download(url, data, input_name) {
var $iframe,
iframe_doc,
iframe_html;
if (($iframe = $('#download_iframe')).length === 0) {
$iframe = $("<iframe id='download_iframe'" +
" style='display: none' src='about:blank'></iframe>"
).appendTo("body");
}
iframe_doc = $iframe[0].contentWindow || $iframe[0].contentDocument;
if (iframe_doc.document) {
iframe_doc = iframe_doc.document;
}
iframe_html = "<html><head></head><body><form method='POST' action='" +
url +"'>" +
"<input type=hidden name='" + input_name + "' value='" +
JSON.stringify(data) +"'/></form>" +
"</body></html>";
iframe_doc.open();
iframe_doc.write(iframe_html);
$(iframe_doc).find('form').submit();
}
Demo with click event:
$('#someid').on('click', function() {
ajax_download('/download.action', {'para1': 1, 'para2': 2}, 'dataname');
});
I faced the same issue and successfully solved it. My use-case is this.
"Post JSON data to the server and receive an excel file.
That excel file is created by the server and returned as a response to the client. Download that response as a file with custom name in browser"
$("#my-button").on("click", function(){
// Data to post
data = {
ids: [1, 2, 3, 4, 5]
};
// Use XMLHttpRequest instead of Jquery $ajax
xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
var a;
if (xhttp.readyState === 4 && xhttp.status === 200) {
// Trick for making downloadable link
a = document.createElement('a');
a.href = window.URL.createObjectURL(xhttp.response);
// Give filename you wish to download
a.download = "test-file.xls";
a.style.display = 'none';
document.body.appendChild(a);
a.click();
}
};
// Post data to URL which handles post request
xhttp.open("POST", excelDownloadUrl);
xhttp.setRequestHeader("Content-Type", "application/json");
// You should set responseType as blob for binary responses
xhttp.responseType = 'blob';
xhttp.send(JSON.stringify(data));
});
The above snippet is just doing following
Posting an array as JSON to the server using XMLHttpRequest.
After fetching content as a blob(binary), we are creating a downloadable URL and attaching it to invisible "a" link then clicking it. I did a POST request here. Instead, you can go for a simple GET too. We cannot download the file through Ajax, must use XMLHttpRequest.
Here we need to carefully set few things on the server side. I set few headers in Python Django HttpResponse. You need to set them accordingly if you use other programming languages.
# In python django code
response = HttpResponse(file_content, content_type="application/vnd.openxmlformats-officedocument.spreadsheetml.sheet")
Since I download xls(excel) here, I adjusted contentType to above one. You need to set it according to your file type. You can use this technique to download any kind of files.
Ok, based on ndpu's code heres an improved (I think) version of ajax_download;-
function ajax_download(url, data) {
var $iframe,
iframe_doc,
iframe_html;
if (($iframe = $('#download_iframe')).length === 0) {
$iframe = $("<iframe id='download_iframe'" +
" style='display: none' src='about:blank'></iframe>"
).appendTo("body");
}
iframe_doc = $iframe[0].contentWindow || $iframe[0].contentDocument;
if (iframe_doc.document) {
iframe_doc = iframe_doc.document;
}
iframe_html = "<html><head></head><body><form method='POST' action='" +
url +"'>"
Object.keys(data).forEach(function(key){
iframe_html += "<input type='hidden' name='"+key+"' value='"+data[key]+"'>";
});
iframe_html +="</form></body></html>";
iframe_doc.open();
iframe_doc.write(iframe_html);
$(iframe_doc).find('form').submit();
}
Use this like this;-
$('#someid').on('click', function() {
ajax_download('/download.action', {'para1': 1, 'para2': 2});
});
The params are sent as proper post params as if coming from an input rather than as a json encoded string as per the previous example.
CAVEAT: Be wary about the potential for variable injection on those forms. There might be a safer way to encode those variables. Alternatively contemplate escaping them.
My approach is completly based on jQuery. The problem for me was that it has to be a POST-HTTP call. And I wanted it to be done by jQuery alone.
The solution:
$.ajax({
type: "POST",
url: "/some/webpage",
headers: {'X-CSRF-TOKEN': csrfToken},
data: additionalDataToSend,
dataType: "text",
success: function(result) {
let blob = new Blob([result], { type: "application/octetstream" });
let a = document.createElement('a');
a.href = window.URL.createObjectURL(blob);
a.download = "test.xml";;
document.body.appendChild(a);
a.click();
document.body.removeChild(a);
window.URL.revokeObjectURL(a.href);
...
},
error: errorDialog
});
Explanation:
What I and many others do is to create a link on the webpage, indicating that the target should be downloaded and putting the result of the http-request as the target. After that I append the link to the document than simply clicking the link and removing the link afterwards. You don't need an iframe anymore.
The magic lies in the lines
let blob = new Blob([result], { type: "application/octetstream" });
a.href = window.URL.createObjectURL(blob);
The interesting point is that this solution is only working with a "blob". As you can see in other answers, some are simply using a blob but not explaining why and how to create it.
As you can read e.g. in the Mozilla developer documentation you need a file, media ressource or blob for the function "createObjectURL()" to work. The problem is that your http-response might not be any of those.
Therefore the first thing you must do is to convert your response to a blob. This is what the first line does. Then you can use the "createObjectURL" with your newly created blob.
If you than click the link your browser will open a file-save dialog and you can save your data. Obviously it s possible that you cannot define a fixed filename for your file to download. Then you must make your response more complex like in the answer from Luke.
And don't forget to free up the memory especially when you are working with large files. For more examples and information you can look at the details of the JS blob object
Here is what I did, pure javascript and html. Did not test it but this should work in all browsers.
Javascript Function
var iframe = document.createElement('iframe');
iframe.id = "IFRAMEID";
iframe.style.display = 'none';
document.body.appendChild(iframe);
iframe.src = 'SERVERURL'+'?' + $.param($scope.filtro);
iframe.addEventListener("load", function () {
console.log("FILE LOAD DONE.. Download should start now");
});
Using just components that is supported in all browsers no additional
libraries.
Here is my server side JAVA Spring controller code.
#RequestMapping(value = "/rootto/my/xlsx", method = RequestMethod.GET)
public void downloadExcelFile(#RequestParam(value = "param1", required = false) String param1,
HttpServletRequest request, HttpServletResponse response)
throws ParseException {
Workbook wb = service.getWorkbook(param1);
if (wb != null) {
try {
String fileName = "myfile_" + sdf.format(new Date());
response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
response.setHeader("Content-disposition", "attachment; filename=\"" + fileName + ".xlsx\"");
wb.write(response.getOutputStream());
response.getOutputStream().close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
How to DOWNLOAD a file after receiving it by AJAX
It’s convenient when the file is created for a long time and you need to show PRELOADER
Example when submitting a web form:
<script>
$(function () {
$('form').submit(function () {
$('#loader').show();
$.ajax({
url: $(this).attr('action'),
data: $(this).serialize(),
dataType: 'binary',
xhrFields: {
'responseType': 'blob'
},
success: function(data, status, xhr) {
$('#loader').hide();
// if(data.type.indexOf('text/html') != -1){//If instead of a file you get an error page
// var reader = new FileReader();
// reader.readAsText(data);
// reader.onload = function() {alert(reader.result);};
// return;
// }
var link = document.createElement('a'),
filename = 'file.xlsx';
// if(xhr.getResponseHeader('Content-Disposition')){//filename
// filename = xhr.getResponseHeader('Content-Disposition');
// filename=filename.match(/filename="(.*?)"/)[1];
// filename=decodeURIComponent(escape(filename));
// }
link.href = URL.createObjectURL(data);
link.download = filename;
link.click();
}
});
return false;
});
});
</script>
Optional functional is commented out to simplify the example.
No need to create temporary files on the server.
On jQuery v2.2.4 OK. There will be an error on the old version:
Uncaught DOMException: Failed to read the 'responseText' property from 'XMLHttpRequest': The value is only accessible if the object's 'responseType' is '' or 'text' (was 'blob').
function downloadURI(uri, name)
{
var link = document.createElement("a");
link.download = name;
link.href = uri;
link.click();
}
I try to download a CSV file and then do something after download has finished. So I need to implement an appropriate callback function.
Using window.location="..." is not a good idea because I cannot operate the program after finishing download. Something like this, change header so it is not a good idea.
fetch is a good alternative however it cannot support IE 11. And window.URL.createObjectURL cannot support IE 11.You can refer this.
This is my code, it is similar to the code of Shahrukh Alam. But you should take care that window.URL.createObjectURL maybe create memory leaks. You can refer this. When response has arrived, data will be stored into memory of browser. So before you click a link, the file has been downloaded. It means that you can do anything after download.
$.ajax({
url: 'your download url',
type: 'GET',
}).done(function (data, textStatus, request) {
// csv => Blob
var blob = new Blob([data]);
// the file name from server.
var fileName = request.getResponseHeader('fileName');
if (window.navigator && window.navigator.msSaveOrOpenBlob) { // for IE
window.navigator.msSaveOrOpenBlob(blob, fileName);
} else { // for others
var url = window.URL.createObjectURL(blob);
const a = document.createElement('a');
a.style.display = 'none';
a.href = url;
a.download = fileName;
document.body.appendChild(a);
a.click();
window.URL.revokeObjectURL(url);
//Do something after download
...
}
}).then(after_download)
}
Adding some more things to above answer for downloading a file
Below is some java spring code which generates byte Array
#RequestMapping(value = "/downloadReport", method = { RequestMethod.POST })
public ResponseEntity<byte[]> downloadReport(
#RequestBody final SomeObejct obj, HttpServletResponse response) throws Exception {
OutputStream out = new ByteArrayOutputStream();
// write something to output stream
HttpHeaders respHeaders = new HttpHeaders();
respHeaders.setContentType(MediaType.APPLICATION_OCTET_STREAM);
respHeaders.add("X-File-Name", name);
ByteArrayOutputStream bos = (ByteArrayOutputStream) out;
return new ResponseEntity<byte[]>(bos.toByteArray(), respHeaders, HttpStatus.CREATED);
}
Now in javascript code using FileSaver.js ,can download a file with below code
var json=angular.toJson("somejsobject");
var url=apiEndPoint+'some url';
var xhr = new XMLHttpRequest();
//headers('X-File-Name')
xhr.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 201) {
var res = this.response;
var fileName=this.getResponseHeader('X-File-Name');
var data = new Blob([res]);
saveAs(data, fileName); //this from FileSaver.js
}
}
xhr.open('POST', url);
xhr.setRequestHeader('Authorization','Bearer ' + token);
xhr.setRequestHeader('Content-Type', 'application/json');
xhr.responseType = 'arraybuffer';
xhr.send(json);
The above will download file
In Rails, I do it this way:
function download_file(file_id) {
let url = '/files/' + file_id + '/download_file';
$.ajax({
type: 'GET',
url: url,
processData: false,
success: function (data) {
window.location = url;
},
error: function (xhr) {
console.log(' Error: >>>> ' + JSON.stringify(xhr));
}
});
}
The trick is the window.location part. The controller's method looks like:
# GET /files/{:id}/download_file/
def download_file
send_file(#file.file,
:disposition => 'attachment',
:url_based_filename => false)
end
Use window.open https://developer.mozilla.org/en-US/docs/Web/API/Window/open
For example, you can put this line of code in a click handler:
window.open('/file.txt', '_blank');
It will open a new tab (because of the '_blank' window-name) and that tab will open the URL.
Your server-side code should also have something like this:
res.set('Content-Disposition', 'attachment; filename=file.txt');
And that way, the browser should prompt the user to save the file to disk, instead of just showing them the file. It will also automatically close the tab that it just opened.
The HTML Code :
<button type="button" id="GetFile">Get File!</button>
The jQuery Code :
$('#GetFile').on('click', function () {
$.ajax({
url: 'https://s3-us-west-2.amazonaws.com/s.cdpn.io/172905/test.pdf',
method: 'GET',
xhrFields: {
responseType: 'blob'
},
success: function (data) {
var a = document.createElement('a');
var url = window.URL.createObjectURL(data);
a.href = url;
a.download = 'myfile.pdf';
document.body.append(a);
a.click();
a.remove();
window.URL.revokeObjectURL(url);
}
});
});
Ok so here is the working code when Using MVC and you are getting your file from a controller
lets say you have your byte array declare and populate, the only thing you need to do is to use the File function (using System.Web.Mvc)
byte[] bytes = .... insert your bytes in the array
return File(bytes, System.Net.Mime.MediaTypeNames.Application.Octet, "nameoffile.exe");
and then, in the same controller, add thoses 2 functions
protected override void OnResultExecuting(ResultExecutingContext context)
{
CheckAndHandleFileResult(context);
base.OnResultExecuting(context);
}
private const string FILE_DOWNLOAD_COOKIE_NAME = "fileDownload";
/// <summary>
/// If the current response is a FileResult (an MVC base class for files) then write a
/// cookie to inform jquery.fileDownload that a successful file download has occured
/// </summary>
/// <param name="context"></param>
private void CheckAndHandleFileResult(ResultExecutingContext context)
{
if (context.Result is FileResult)
//jquery.fileDownload uses this cookie to determine that a file download has completed successfully
Response.SetCookie(new HttpCookie(FILE_DOWNLOAD_COOKIE_NAME, "true") { Path = "/" });
else
//ensure that the cookie is removed in case someone did a file download without using jquery.fileDownload
if (Request.Cookies[FILE_DOWNLOAD_COOKIE_NAME] != null)
Response.Cookies[FILE_DOWNLOAD_COOKIE_NAME].Expires = DateTime.Now.AddYears(-1);
}
and then you will be able to call your controller to download and get the "success" or "failure" callback
$.fileDownload(mvcUrl('name of the controller'), {
httpMethod: 'POST',
successCallback: function (url) {
//insert success code
},
failCallback: function (html, url) {
//insert fail code
}
});
I found a fix that while it's not actually using ajax it does allow you to use a javascript call to request the download and then get a callback when the download actually starts. I found this helpful if the link runs a server side script that takes a little bit to compose the file before sending it. so you can alert them that it's processing, and then when it does finally send the file remove that processing notification. which is why I wanted to try to load the file via ajax to begin with so that I could have an event happen when the file is requested and another when it actually starts downloading.
the js on the front page
function expdone()
{
document.getElementById('exportdiv').style.display='none';
}
function expgo()
{
document.getElementById('exportdiv').style.display='block';
document.getElementById('exportif').src='test2.php?arguments=data';
}
the iframe
<div id="exportdiv" style="display:none;">
<img src="loader.gif"><br><h1>Generating Report</h1>
<iframe id="exportif" src="" style="width: 1px;height: 1px; border:0px;"></iframe>
</div>
then the other file:
<!DOCTYPE html>
<html>
<head>
<script>
function expdone()
{
window.parent.expdone();
}
</script>
</head>
<body>
<iframe id="exportif" src="<?php echo "http://10.192.37.211/npdtracker/exportthismonth.php?arguments=".$_GET["arguments"]; ?>"></iframe>
<script>document.getElementById('exportif').onload= expdone;</script>
</body></html>
I think there's a way to read get data using js so then no php would be needed. but I don't know it off hand and the server I'm using supports php so this works for me. thought I'd share it in case it helps anyone.
If the server is writing the file back in the response (including cookies if
you use them to determine whether the file download started), Simply create a form with the values and submit it:
function ajaxPostDownload(url, data) {
var $form;
if (($form = $('#download_form')).length === 0) {
$form = $("<form id='download_form'" + " style='display: none; width: 1px; height: 1px; position: absolute; top: -10000px' method='POST' action='" + url + "'></form>");
$form.appendTo("body");
}
//Clear the form fields
$form.html("");
//Create new form fields
Object.keys(data).forEach(function (key) {
$form.append("<input type='hidden' name='" + key + "' value='" + data[key] + "'>");
});
//Submit the form post
$form.submit();
}
Usage:
ajaxPostDownload('/fileController/ExportFile', {
DownloadToken: 'newDownloadToken',
Name: $txtName.val(),
Type: $txtType.val()
});
Controller Method:
[HttpPost]
public FileResult ExportFile(string DownloadToken, string Name, string Type)
{
//Set DownloadToken Cookie.
Response.SetCookie(new HttpCookie("downloadToken", DownloadToken)
{
Expires = DateTime.UtcNow.AddDays(1),
Secure = false
});
using (var output = new MemoryStream())
{
//get File
return File(output.ToArray(), "application/vnd.ms-excel", "NewFile.xls");
}
}
I have tried Ajax and HttpRequest ways to get my result download file but I've failed, finally I've solved my problem using these steps:
implemented a simple hidden form in my html code:
<form method="post" id="post_form" style="display:none" action="amin.php" >
<input type="hidden" name="action" value="export_xlsx" />
<input type="hidden" name="post_form_data" value="" />
</form>
input with 'action' name is for calling function in my php code,
input with 'post_form_data' name for sending long data of a table which were not possible to send with GET. this data was encoded to json, and put json in input:
var list = new Array();
$('#table_name tr').each(function() {
var row = new Array();
$(this).find('td').each(function() {
row.push($(this).text());
});
list.push(row);
});
list = JSON.stringify(list);
$("input[name=post_form_data]").val(list);
now, the form is ready with my desire values in inputs, just need to trigger the submit.
document.getElementById('post_form').submit();
and done!
while my result is a file (xlsx file for me) the page wouldn't be redirected and instantly the file starts to download in last page, so no need to useiframe or window.open etc.
if you are trying to do something like this, this should be an easy trick 😉.
If you want to use jQuery File Download , please note this for IE.
You need to reset the response or it will not download
//The IE will only work if you reset response
getServletResponse().reset();
//The jquery.fileDownload needs a cookie be set
getServletResponse().setHeader("Set-Cookie", "fileDownload=true; path=/");
//Do the reset of your action create InputStream and return
Your action can implement ServletResponseAware to access getServletResponse()
It is certain that you can not do it through Ajax call.
However, there is a workaround.
Steps :
If you are using form.submit() for downloading the file, what you can do is :
Create an ajax call from client to server and store the file stream inside the session.
Upon "success" being returned from server, call your form.submit() to just stream the file stream stored in the session.
This is helpful in case when you want to decide whether or not file needs to be downloaded after making form.submit(), eg: there can be a case where on form.submit(), an exception occurs on the server side and instead of crashing, you might need to show a custom message on the client side, in such case this implementation might help.
there is another solution to download a web page in ajax. But I am referring to a page that must first be processed and then downloaded.
First you need to separate the page processing from the results download.
1) Only the page calculations are made in the ajax call.
$.post("CalculusPage.php", { calculusFunction: true, ID: 29, data1: "a", data2: "b" },
function(data, status)
{
if (status == "success")
{
/* 2) In the answer the page that uses the previous calculations is downloaded. For example, this can be a page that prints the results of a table calculated in the ajax call. */
window.location.href = DownloadPage.php+"?ID="+29;
}
}
);
// For example: in the CalculusPage.php
if ( !empty($_POST["calculusFunction"]) )
{
$ID = $_POST["ID"];
$query = "INSERT INTO ExamplePage (data1, data2) VALUES ('".$_POST["data1"]."', '".$_POST["data2"]."') WHERE id = ".$ID;
...
}
// For example: in the DownloadPage.php
$ID = $_GET["ID"];
$sede = "SELECT * FROM ExamplePage WHERE id = ".$ID;
...
$filename="Export_Data.xls";
header("Content-Type: application/vnd.ms-excel");
header("Content-Disposition: inline; filename=$filename");
...
I hope this solution can be useful for many, as it was for me.
That's it works so fine in any browser (I'm using asp.net core)
function onDownload() {
const api = '#Url.Action("myaction", "mycontroller")';
var form = new FormData(document.getElementById('form1'));
fetch(api, { body: form, method: "POST"})
.then(resp => resp.blob())
.then(blob => {
const url = window.URL.createObjectURL(blob);
$('#linkdownload').attr('download', 'Attachement.zip');
$('#linkdownload').attr("href", url);
$('#linkdownload')
.fadeIn(3000,
function() { });
})
.catch(() => alert('An error occurred'));
}
<button type="button" onclick="onDownload()" class="btn btn-primary btn-sm">Click to Process Files</button>
<a role="button" href="#" style="display: none" class="btn btn-sm btn-secondary" id="linkdownload">Click to download Attachments</a>
<form asp-controller="mycontroller" asp-action="myaction" id="form1"></form>
function onDownload() {
const api = '#Url.Action("myaction", "mycontroller")';
//form1 is your id form, and to get data content of form
var form = new FormData(document.getElementById('form1'));
fetch(api, { body: form, method: "POST"})
.then(resp => resp.blob())
.then(blob => {
const url = window.URL.createObjectURL(blob);
$('#linkdownload').attr('download', 'Attachments.zip');
$('#linkdownload').attr("href", url);
$('#linkdownload')
.fadeIn(3000,
function() {
});
})
.catch(() => alert('An error occurred'));
}
I struggled with this issue for a long time. Finally an elegant external library suggested here helped me out.
I'm evaluating Node.js for possible replacement of my current push functionality on a Java Web App. I wrote a simple long polling server that works like an intermediary between the client and the Java back-end. The client makes a request to subscribe, and then the Java server can notify subscribed clients by calling Node.js. It seems to be working fine so far, but I got the following message which points to a memory leak:
(node) warning: possible EventEmitter memory leak detected. 11 listeners added.
Use emitter.setMaxListeners() to increase limit.
Trace
at EventEmitter.addListener (events.js:168:15)
at EventEmitter.once (events.js:189:8)
at route (C:\Users\Juan Pablo\pushserver.js:42:12)
at Server.onRequest (C:\Users\Juan Pablo\pushserver.js:32:3)
at Server.EventEmitter.emit (events.js:91:17)
at HTTPParser.parser.onIncoming (http.js:1793:12)
at HTTPParser.parserOnHeadersComplete [as onHeadersComplete] (http.js:111:23
)
at Socket.socket.ondata (http.js:1690:22)
at TCP.onread (net.js:402:27)
I have a line of code that logs the existing listeners whenever a notify event is emitted. I've had it running for a while and it shows that there is only one listener per subscribed client (as should be), but this line wasn't on the code when I got the warning message. The code was exactly the same except for that line tough.
This is the push server's code (it's a bit rudimentary since I'm still learning Node.js):
var http = require('http');
var url = require("url");
var qs = require("querystring");
var events = require('events');
var util = require('util');
var emitter = new events.EventEmitter;
function onRequest(request, response)
{
var pathname = url.parse(request.url).pathname;
console.log("Request for " + pathname + " received.");
request.setEncoding("utf8");
if (request.method == 'POST')
{
var postData = "";
request.addListener("data", function(postDataChunk)
{
postData += postDataChunk;
console.log("Received POST data chunk '"+ postDataChunk + "'.");
});
request.addListener("end", function()
{
route(pathname, response, postData);
});
}
else if (request.method=='GET')
{
var urlParts = url.parse(request.url, true);
route(pathname, response, urlParts.query);
}
}
function route(pathname, response, data)
{
switch (pathname)
{
case "/subscription":
emitter.once("event:notify", function(ids)
{
response.writeHead(200, {"Content-Type": "text/html", "Access-Control-Allow-Origin": "*"});
response.write(JSON.stringify(ids));
response.end();
});
break;
case "/notification":
//show how many listeners exist
console.log(util.inspect(emitter.listeners('event:notify'));
emitter.emit("event:notify", data.ids);
response.writeHead(200, {"Content-Type": "text/html", "Access-Control-Allow-Origin": "*"});
response.write(JSON.stringify(true));
response.end();
break;
default:
console.log("No request handler found for " + pathname);
response.writeHead(404, {"Content-Type": "text/plain", "Access-Control-Allow-Origin": "*"});
response.write("404 - Not found");
response.end();
break;
}
}
http.createServer(onRequest).listen(8888);
console.log('Server running at http://127.0.0.1:8888/');
I was under the impression that using emitter.once would automatically remove the event listener once it was used, so I don't know how 11 listeners could've been added if there was only one client connected. I'm thinking that perhaps if the client disconnects while waiting for a notification then the associated connection resources are not disposed.
I'm wondering whether I have to manually handle disconnections and if there is actually a leak in there somewhere. Any advice is welcome. Thanks.
If anyone is interested, the above code does leak. The leak occurs when a client disconnects before a notification is sent. To fix this, it is necessary to remove the event listener when a client disconnects abruptly, such as:
case "/subscription":
var notify = function(ids)
{
response.writeHead(200, {"Content-Type": "text/html", "Access-Control-Allow-Origin": "*"});
response.write(JSON.stringify(ids));
response.end();
}
emitter.once("event:notify", notify);
//event will be removed when connection is closed
request.on("close", function()
{
emitter.removeListener("event:notify", notify);
});
break;
This is solved at last with "timeout" attribute of jQuery AJAX (and JSONP). See my own answer !
Please see the updated part, I have tried with applet too. And will not hesitate to accept your answer if you can give a solution with applet implementation.
I am working with a Java based web application. My requirement is to check whether a particular port (say 1935) is open or blocked at client's end. I have implemented a "jsonp" (why 'jsonp' ? i found that 'http' request through AJAX cannot work for corssdomain for browsers 'same origin policy') AJAX call to one of my server containing particular port. And if the server returns xhr.status == 200 the port is open. Here is a drawback that I can't make the execution-flow wait (synchronous) until the call completes. Here is the JavaScript function I am using.
Any alternative solution (must be a client-sided thing must be parallel with my application, please dont suggest python/php/other languages) is also welcome. Thanks for your time.
function checkURL() {
var url = "http://10.0.5.255:1935/contextname" ;
var isAccessible = false;
$.ajax({
url: url,
type: "get",
cache: false,
dataType: 'jsonp',
crossDomain : true,
asynchronous : false,
jsonpCallback: 'deadCode',
complete : function(xhr, responseText, thrownError) {
if(xhr.status == "200") {
isAccessible = true;
alert("Request complete, isAccessible==> " + isAccessible); // this alert does not come when port is blocked
}
}
});
alert("returning isAccessible=> "+ isAccessible); //this alert comes 2 times before and after the AJAX call when port is open
return isAccessible;
}
function deadCode() {
alert("Inside Deadcode"); // this does not execute in any cases
}
---------------------------------------------------------UPDATE----------------------------------------------------------------
I have tried with Java Applet (thanks to Y Martin's suggestion). This is working fine in appletviewer. But when I add the applet in HTML page, it is giving vulnerable results. Vulnerable in the sense, when I change the tab or resize the browser, the value of portAvailable is being altered in the printed message.
Applet Code :
import java.applet.Applet;
import java.awt.Graphics;
import java.net.InetSocketAddress;
import java.net.Socket;
public class ConnectionTestApplet extends Applet {
private static boolean portAvailable;
public void start() {
int delay = 1000; // 1 s
try {
Socket socket = new Socket();
/*****This is my tomcat5.5 which running on port 1935*************/
/***I can view it with url--> http://101.220.25.76:1935/**********/
socket.connect(new InetSocketAddress("101.220.25.76", 1935), delay);
portAvailable = socket.isConnected();
socket.close();
System.out.println("init() giving---> " + portAvailable);
}
catch (Exception e) {
portAvailable = false;
System.out.println("init() giving---> " + portAvailable);
System.out.println("Threw error---> " + e.getMessage());
}
}
public void paint(Graphics g) {
System.out.println("Connection possible---> " + portAvailable);
String msg = "Connection possible---> " + portAvailable;
g.drawString(msg, 10, 30);
}
}
And this is my HTML page (I am hosting it on same computer with a different Tomcat 6 which runs on port 9090. I can view this page with url ---> http://101.220.25.76:9090/test/):
<html>
<body>
<applet code="ConnectionTestApplet" width=300 height=50>
</applet>
</body>
</html>
And how I am doing the port 1935 blocking and openning ?
I have created firewall rule for both inbound and outbound for port 1935.
I check the port 1935 open/blocked scenario by disabling/enabling both rules.
This is my S.S.C.C.E. Now please help me :)
Gotcha !!! I have solved my problem with JSONP and jQuery AJAX call. I discovered the timeout attribute of jQuery AJAX and my code executed fluently when the port was blocked or opened. Here is the solution for future visitors. Thanks to all answerers for contribution.
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<script type="text/javascript" src="jquery-1.7.2-min.js"></script>
</head>
<body>
<script type"text/javascript">
var isAccessible = null;
function checkConnection() {
var url = "http://101.212.33.60:1935/test/hello.html" ;
$.ajax({
url: url,
type: "get",
cache: false,
dataType: 'jsonp', // it is for supporting crossdomain
crossDomain : true,
asynchronous : false,
jsonpCallback: 'deadCode',
timeout : 1500, // set a timeout in milliseconds
complete : function(xhr, responseText, thrownError) {
if(xhr.status == "200") {
isAccessible = true;
success(); // yes response came, esecute success()
}
else {
isAccessible = false;
failure(); // this will be executed after the request gets timed out due to blockage of ports/connections/IPs
}
}
});
}
$(document).ready( function() {
checkConnection(); // here I invoke the checking function
});
</script>
</body>
</html>
I don't think you understand the use cases for JSONP and it's not possible to test open ports with it. http://en.wikipedia.org/wiki/JSONP
If you want a client side solution it could be possible with websockets, but this is only available on new browsers like chrome or ff. Otherwise request a server side script which does the ping. For example - with a curl script: curl and ping - how to check whether a website is either up or down?
Here is a Java code as an Applet to test server/port connectivity:
import java.io.*;
import java.net.*;
public class ConnectionTestApplet extends Applet {
public void start() {
boolean portAvailable = false;
int delay = 1000; // 1 s
try {
Socket socket = new Socket();
socket.connect(new InetSocketAddress("server.domain.com", 1935), delay);
portAvailable = socket.isConnected();
socket.close();
} catch (UnknownHostException uhe) {
uhe.printStackTrace();
} catch (IOException ioe) {
ioe.printStackTrace();
}
System.out.println("Connection possible: " + portAvailable);
}
}
You still have to get the information out of the applet to do something else with that result. The easiest way is to redirect the browser thanks to getAppletContext().showDocument(url)
Instead of an applet a flash component may be used. Using the Socket class available in ActionCcript one can open a tcp connection from flash to a port on a server to check if its open. But based on the flash player version a policy file needs to be placed on the server to which the socket is opened.
Check this out:
http://blog.andlabs.org/2010/12/port-scanning-with-html5-and-js-recon.html
With JS-Recon, you can do port scanning with javascript. You can simply point it to your local IP address. I believe it works by making a web sockets/cors connection to an arbitrary desintation ip/socket and measuring the timeouts. It is not a perfect approach, but this may be the limit of javascript ultimately.
If you can do it in a java applet/flash application, that may be better ultimately as they have lower-level access.
You cannot do this in JavaScript because it doesn't have true socket support, with JavaScript you can only test for the presence of HTTP socket. You could use Java (JavaScript is not Java) and write a proper Java Applet to do it.
You should also read this Q&A How to Ping in java
Try using isReachable
In JavaScript, you have to work-around the asynchronous issue. Here is a proposal:
The HTML page displays an animated image as a progress bar
You invoke the checkURL
After either receiving the callback or a defined timeout, you change display for an error message or do on with the job to do
Based on the following document with the use of XMLHttpRequest, here is a code example for checkURL:
var myrequest = new ajaxRequest();
var isAccessible = false;
myrequest._timeout = setTimeout(function() {
myrequest.abort();
displayErrorMessage();
},
1000
) //end setTimeout
myrequest.onreadystatechange = function() {
if (myrequest.readyState == 4) { //if request has completed
if (myrequest.status == 200) {
isAccessible = false;
goOnWithTheJob();
} else {
displayErrorMessage();
}
}
myrequest.open("GET", url, true);
myrequest.send(null); //send GET request
// do nothing - wait for either timeout or readystate callback
This code lets 1 second to get the 200 response from a HTTP GET on a basic resource.
In your local test, you get an immediate answer because the system answers connection reset if the port is closed but a firewall just does not answer.
Even if the open method may be used synchronously, I recommend the use of a timer because the code is likely to wait for TCP timeouts and retries (3 x 1 minute ?) as a firewall usually just drops packets on closed ports and may reject ICMP packets, preventing you to test availability thanks to ping. And I imagine such a long wait is not expected for such a check.
I am occasional frontend/javascript/jQuery guy, so this may not be 100% professional, but it is good enough and it solved my similar problem:
ping_desktop_app = $.get({
url: "http://127.0.0.1:#{desktop_app_port}",
dataType: 'jsonp',
})
$(#).parent().find(".click-me-to-use-desktop-app").click ->
if ping_desktop_app.status == 200
$.get({
url: "http://127.0.0.1:#{desktop_app_port}/some_command/123123",
dataType: 'jsonp',
})
else
alert("Please run your desktop app and refresh browser")
I could not check whether port is open (desktop app is running) on server side because views are cached, so I needed to check the localhost/port right before user click in browser
Edits translating to JS are welcome