How to download all files in the file directory when clicking the export or download at the same time？
At present, all the files in the file directory have been obtained, then all the files are placed in the list, and then the stream is written after traversing all the files. However, when importing the second file, it will report cannot reset buffer after response has been committed
The source of the problem is in this code： // response.reset();
Code：
String filePath = "/code/data/";
// Get all file addresses of the directory
List<String> filePathList = getFilePath(filePath);
//Create thread pool
for (String str : filePathList){
download(request, response, str);
}
private void download(HttpServletRequest request,
HttpServletResponse response,String filePath) {
File file = new File(filePath);
//Gets the file name.
String fileName = file.getName();
InputStream fis = null;
try {
fis = new FileInputStream(file);
request.setCharacterEncoding("UTF-8");
String agent = request.getHeader("User-Agent").toUpperCase();
if ((agent.indexOf("MSIE") > 0) || ((agent.indexOf("RV") != - 1) &&
(agent.indexOf("FIREFOX") == -1))) {
fileName = URLEncoder.encode(fileName, "UTF-8");
} else {
fileName = new String(fileName.getBytes("UTF-8"), "ISO8859-1");
}
// response.reset();
response.setCharacterEncoding("UTF-8");
response.setContentType("application/force-download");
// Set forced download not to open
response.addHeader("Content-Disposition",
"attachment; filename=" + fileName);
response.setHeader("Content-Length", String.valueOf(file.length()));
byte[] b = new byte[1024];
int len;
while ((len = fis.read(b)) != - 1) {
response.getOutputStream().write(b, 0, len);
}
response.flushBuffer();
fis.close();
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
What are the good solutions Thanks
I have not read your code in detail because the bad formatting makes my head hurt.
However, from a superficial reading, it looks like this server-side code is trying to deliver multiple files in response to a single HTTP request.
AFAIK, that is not possible. The HTTP request / response model does not support this. It certainly does not allow a servlet to:
change response headers after the response output stream has been opened
do anything after the response output stream has been closed.
(Your code appears to be trying to do both of those things!)
So, you have to do it differently. Here are some possibilities:
On the server side, assemble all of the files to be downloaded into (say) a temporary ZIP file and then send that. Leave it to the user to unpack the ZIP file ... or not ... as they want.
This is often the best approach. Imagine how annoyed you would be if a few thousand separate files unexpectedly landed in your web browser's Downloads folder.
As 1. and also do something on the client side to transparently unpack the files from the ZIP and put them in the right place in the client's file system.
The "something" could be custom javascript embedded in the web page, or a custom client implemented in Java ... or any other language. (But in the former case, there may be a security issue in allowing sandboxed javascript to write files in arbitrary places without the user confirming each file ... tedious.)
You might be able to send a "multipart" document as the response. However from what I have read, most browsers don't support multipart for downloads; e.g. some browsers will discard all but the last part. (Note: multipart is not designed for this purpose ...)
Change things so that an HTTP request only downloads one file at a time from the directory, and add some client-side stuff to 1) fetch a list of files from the server and iterate the list, fetching each file.
See also: Download multiple files with a single action
Related
I have a problem with saving files and then downloading them after generating a .war file.
I need to handle the generation of many files after pressing the button by admin in the application. The files are generated using part of the code that was sent using the POST method and second part is from the database.
The files are hundreds / thousands and it is impossible to do it manually. Admin generates files from time to time. The user should be able to download these files from the application.
When I run the application in IntelliJ, app has access to the folders on the disk, so the following code works:
(part of backend class, responfible for saving files in path)
private void saveTextToFile(String text, String fileName) {
String filePathAndName = "/static/myFiles/" + fileName+ ".txt";
ClassLoader classLoader = getClass().getClassLoader();
File file = new File(classLoader.getResource(".").getFile() + filePathAndName );
FileWriter fileWriter = null;
try {
fileWriter = new FileWriter(file);
PrintWriter printWriter = new PrintWriter(fileWriter);
printWriter.print(text);
printWriter.close();
} catch (IOException e) {
e.printStackTrace();
}
}
The file was saved in folder:
C:\Users...\myProject\target\classes\static.
(and this is link to generated file in thymeleaf)
<html xmlns:th="http://www.thymeleaf.org">
<a th:href="#{|/myFiles/${thisIsMyFileName}|}">Download file</a>
</html>
Unfortunately, when I generate the .war file and run it, the files are not saved in the application's "resources" folder. As a result, the user cannot download this file via the link generated by thymeleaf.
In general, you do not want to upload anything into your application's files - it opens you to many security problems if someone figures out how to overwrite parts of the application, and in most application servers, it is simply not writable.
A much better approach is to have a designated server folder where you can write things. For example, you could have the following in your configuration:
myapp.base-folder = /any/server/folder/you/want
And then, in the code, you would find that folder as follows:
// env is an #AutoWired private Environment
File baseFolder = new File(env.getProperty("myapp.base-folder"));
I find this better than using a database (as #Stultuske suggested in comments), because databases are great for relations, but mostly overkill for actual files. Files can be accessed externally without firing up the database with minimal hassle, and having them separate keeps your database much easier to backup.
To generate links to the file, simply create a link as you would to any other type of request
<a th:href="#{/file/${fileId}|}">Download file</a>
-- and to handle it in the server, but returning the contents of the file:
#GetMapping(value="/file/{id}")
public StreamingResponseBody getFile(#PathVariable long id) throws IOException {
File f = new File(baseFolder, ""+id); // numerical id prevents filesytem traversal
InputStream in;
if (f.exists()) {
in = new BufferedInputStream(new FileInputStream(f));
} else {
// you could also signal error by returning a 404
in = new BufferedInputStream(getClass().getClassLoader()
.getResourceAsStream("static/img/unknown-id.jpg"));
}
return new StreamingResponseBody() {
#Override
public void writeTo(OutputStream os) throws IOException {
FileCopyUtils.copy(in, os);
}
};
}
I prefer numerical IDs to avoid hassles with path traversal - but you can easily use string filenames instead, and deal with security issues by carefully checking that the canonical path of the requested file starts with the canonical path of your baseFolder
I'm interested in having a button which takes a pic from the user's computer and uploads it on my server.
I managed to solve the server uploading part, but I'm having difficulties in handling the path from the user computer. Vaadin Upload does not provide me full path, but I want it to be dynamic. Looking at the documentation, they use some temp location, but I don't know how to implement that.
public OutputStream receiveUpload(String filename,
String mimeType) {
// Create upload stream
FileOutputStream fos = null; // Stream to write to
try {
// Open the file for writing.
file = new File("/tmp/uploads/" + filename);
fos = new FileOutputStream(file);
} catch (final java.io.FileNotFoundException e) {
new Notification("Could not open file<br/>",
e.getMessage(),
Notification.Type.ERROR_MESSAGE)
.show(Page.getCurrent());
return null;
}
return fos; // Return the output stream to write to
}
I'm expecting that when the File Chooser closes, I get some kind of file path or handler so I can put it on my server.
In the filename argument you will have the name of uploaded file.
The path of the file however is not sent to the server, this is one of the restrictions of web applications / web browsers.
With the code you use, you will have a copy of the uploaded file on your server in the tmp folder.
There is no way to directly access files on client computers through the web browser.
I have a database where the user doesn't has access to.
Still I can go to the database and "read" the documents with for example
var db:NotesDatabase = sessionAsSigner.getDatabase("","somedir/some.nsf");
In this database there's a pdf file I would like to open or download. I have the filename and the unid . If the user had acces to the database I could do it with
http(s)://[yourserver]/[application.nsf] /xsp/.ibmmodres/domino/OpenAttachment/ [application.nsf]/[UNID|/$File/[AttachmentName]?Open
How can I do it with sessionAsSigner without putting a $PublicAccess=1 field on the form ?
edit:
the pdf file is stored as attachment in a richtextfield
second edit
I'm trying to use the XSnippet from Naveen and made some changes
The error message I get is : 'OutStream' not found
The code I tried is :
response.reset();
response.setContentType("application/pdf");
response.setHeader("Content-Disposition", "inline; filename=" + zipFileName);
var embeddedObj:NotesEmbeddedObject = null;
var bufferInStream:java.io.BufferedInputStream = null;
var outStream:java.io.OutputStream = response.getOutputStream();
embeddedObj = downloadDocument.getAttachment(fileName);
if (embeddedObj != null) {
bufferInStream = new java.io.BufferedInputStream(embeddedObj.getInputStream());
var bufferLength = bufferInStream.available();
var data = new byte[bufferLength];
bufferInStream.read(data, 0, bufferLength); // Read the attachment data
ON THE NEXT LINE IS THE PROBLEM
OutStream.write(data); // Write attachment into pdf
bufferInStream.close();
embeddedObj.recycle();
}
downloadDocument.recycle();
outStream.flush();
outStream.close();
facesContext.responseComplete();
Create an XAgent (= XPage without rendering) which takes datebase + documentid + filename as URL parameters and delivers the file as response OutputStream.
The URL would be
http(s)://[yourserver]/download.nsf/download.xsp?db=[application.nsf]&unid=[UNID]&attname=[AttachmentName]
for an XAgent download.xsp in a database download.nsf.
The code behind the XAgent runs as sessionAsSigner and is able to read the file even the user itself has no right to access file's database.
Use Eric's blog (+ Java code) as a starting point. Replace "application/json" with "application/pdf" and stream pdf file instead of json data.
As an alternative you can adapt this XSnippet code from Thomas Adrian. Use download() together with grabFile() to write your pdf-File to OutputStream.
Instead of extracting attachment file to path and reading it from there you can stream the attachment right from document to response's OutputStream. Here is an XSnippet from Naveen Maurya as a good example.
If you can get the PDF file as a stream, you should be able to use the OutputStream of the external context's response.
Stephan Wissel has a blog posting about writing out an ODF file so you should be able to cut that up as a starting point.
http://www.wissel.net/blog/d6plinks/SHWL-8248MT
You already have the db so, you will just need to know the UNID of the document.
var doc = db.getDocumentByUNID(unid) 'unid is a supplied param
var itm:RichTextItem = doc.getFirstItem("Body") 'assuming file is in body field
Once you have the itm, you can loop round all of the embeddedObjects and get the pdf file. At this point, I don't know if you can stream it directly or if you have to detach it, but assuming you detach it, you will then use something like this.
File file = new File("path to file");
FileInputStream fileIn = new FileInputStream(file);
Don't forget to clean up the temporarily detached file
I'm trying to zip files from server into a folder using ZipOutputStream.
After archive download it can't be opened after double click. Error "The compressed (zipped) folder is invalid" occures. But if I open it from context menu - > 7zip -> open file it works normal. What can be reason of the problem?
sourceFileName="./file.txt"'
sourceFile = new File(sourceFileName);
try {
// set the content type and the filename
responce.setContentType("application/zip");
response.addHeader("Content-Disposition", "attachment; filename=" + sourceFileName + ".zip");
responce.setContentLength((int) sourceFile.length());
// get a ZipOutputStream, so we can zip our files together
ZipOutputStream outZip = new ZipOutputStream((responce.getOutputStream());
// Add ZIP entry to output stream.
outZip.putNextEntry(new ZipEntry(sourceFile.getName()));
int length = 0;
byte[] bbuf = new byte[(int) sourceFile.length()];
DataInputStream in = new DataInputStream(new FileInputStream(sourceFile));
while ((in != null) && ((length = in.read(bbuf)) != -1)) {
outZip.write(bbuf, 0, length);
}
outZip.closeEntry();
in.close();
outZip.flush();
outZip.close();
7Zip can open a wide variety of zip formats, and is relatively tolerant of oddities. Windows double-click requires a relatively specific format and is far less tolerant.
You need to look up the zip format and then look at your file (and "good" ones) with a hex editor (such as Hex Editor Neo), to see what may be wrong.
(One possibility is that you're using the wrong compression algorithm. And there are several other variations to consider as well, particularly whether or not you generate a "directory".)
It could be that a close is missing. It could be that the path encoding in the zip cannot be handled by Windows. It might be that Windows has difficulty with the directory structure, or that a path name contains a (back)slash. So it is detective work, trying different files. If you immediately stream the zip to the HTTP response, then finish has to be called i.o. close.
After the code being posted:
The problem is the setContentLength giving the original file size. But when given, it should give the compressed size.
DataInputStream is not needed, and one should here do a readFully.
responce.setContentType("application/zip");
response.addHeader("Content-Disposition", "attachment; filename=file.zip");
//Path sourcePath = sourceFile.toPath();
Path sourcePath = Paths.get(sourceFileName);
ZipOutputStream outZip = new ZipOutputStream((responce.getOutputStream(),
StandardCharsets.UTF-8);
outZip.putNextEntry(new ZipEntry(sourcePath.getFileName().toString()));
Files.copy(sourcePath, outZip);
outZip.closeEntry();
Either finish or closethe zip at the end.
outZip.finish();
//outZip.close();
in.close();
I am not sure (about the best code style) whether to close the response output stream already oneself.
But when not closing finish() must be called, flush() will not suffice, as at the end data is written to the zip.
For file names with for instance Cyrillic letters, it would be best to add a Unicode charset like UTF-8. In fact let UTF-8 be the Esperanto standard world-wide.
A last note: if only one file one could use GZipOutputstream for file.txt.gz or query the browser's capabilities (request parameters) and deliver it compressed as file.txt.
I know this is a little broad, but here's the situation:
I am using JSP and Java. I have a file located on my server. I would like to add a link to the screen that, when clicked, would open the file for the user to view. The file can either appear in a window in the web browser, or pop up the program needed to open the file (similar to when you are outputting with iText to the screen, where Adobe opens to display the file). I know my output stream already, but how can I write the file to the output stream? Most of what I have read has only dealt with text files, but I might be dealing with image files, etc., as well.
Any help is appreciated!
Thanks!
You need to add certain fields to the response. For a text/csv, you'd do:
response.setContentType("text/csv"); // set MIME type
response.setHeader("Content-Disposition", "attachment; filename=\"" strExportFileName "\"");
Here's a forum on sun about it.
Here's a simple implementation on how to achieve it:
protected void doPost(final HttpServletRequest request,
final HttpServletResponse response) throws ServletException,
IOException {
// extract filename from request
// TODO use a whitelist to avoid [path-traversing][1]
File file = new File(getFileName(request));
InputStream input = new FileInputStream(file);
response.setContentLength((int) file.length());
// TODO map your file to the appropriate MIME
response.setContentType(getMimeType(file));
OutputStream output = response.getOutputStream();
byte[] bytes = new byte[BUFFER_LENGTH];
int read = 0;
while (read != -1) {
read = input.read(bytes, 0, BUFFER_LENGTH);
if (read != -1) {
output.write(bytes, 0, read);
output.flush();
}
}
input.close();
output.close();
}
You need to create a 'download' servlet which writes the file to the response output stream with correct mime types. You can not reliably do this from within a .jsp file.
We usually do it with a 'download servlet' which we set the servletmapping to /downloads, then append path info to identify the asset to serve. The servlet verifies the request is valid, sets the mime header then delivers the file to the output stream. It's straightforward, but keep the J2EE javadocs handy while doing it.