I need some ideas on how I can best solve this problem.
I have a JBoss Seam application running on JBoss 4.3.3
What a small portion of this application does is generate an html and a pdf document based on an Open Office template.
The files that are generated I put inside /tmp/ on the filesystem.
I have tried with System.getProperties("tmp.dir") and some other options, and they always return $JBOSS_HOME/bin
I would like to choose the path $JBOSS_HOME/$DEPLOY/myEAR.ear/myWAR.war/WhateverLocationHere/
However, I don't know how I can programatically choose path without giving an absolute path, or setting $JBOSS_HOME and $DEPLOY.
Anybody know how I can do this?
The second question;
I want to easily preview these generated files. Either through JavaScript, or whatever is the easiest way. However, JavaScript cannot access the filesystem on the server, so I cannot open the file through JavaScript.
Any easy solutions out there?
Not sure how you are generating your PDFs, but if possible, skip the disk IO all together, stash the PDF content in a byte[] and flush it out to the user in a servlet setting the mime type to application/pdf* that responds to a URL which is specified by a link in your client or dynamically set in a <div> by javascript. You're probably taking the memory hit anyways, and in addition to skipping the IO, you don't have to worry about deleting the tmp files when you're done with the preview.
*****I think this is right. Need to look it up.
Not sure I have a complete grasp of what you are trying to achieve, but I'll give it a try anyway:
My assumption is that your final goal is to make some files (PDF, HTML) available to end users via a web application.
In that case, why not have Apache serve those file to the end users, so you only need your JBOSS application to know the path of a directory that is mapped to an Apache virtual host.
So basically, create a file and save it as /var/www/html/myappfiles/tempfile.pdf (the folder your application knows), and then provide http://mydomain.com/myappfiles (an Apache virtual host) to your users. The rest will be done by the web server.
You will have to set an environment variable or system property to let your application know where your folder resides (/var/www/html/myappfiles/ in this example).
Hopefully I was not way off :)
I agree with Peter (yo Pete!). Put the directory outside of your WAR and setup an environment variable pointing to this. Have a read of this post by Jacob Orshalick about how to configure environment variables in Seam :
As for previewing PDFs, have a look at how Google Docs handles previewing PDFs - it displays them as an image. To do this with Java check out the Sun PDF Renderer.
I'm not sure if this works in JBoss, given that you want a path inside a WAR archive, but you could try using ServletContext.getRealPath(String).
However, I personally would not want generated files to be inside my deployed application; instead I would configure an external data directory somewhere like $JBOSS_HOME/server/default/data/myapp
First, most platforms use java.io.tmpdir to set a temporary directory. Some servlet containers redefine this property to be something underneath their tree. Why do you care where the file gets written?
Second, I agree with Nicholas: After generating the PDF on the server side, you can generate a URL that, when clicked, sends the file to the browser. If you use MIME type application/pdf, the browser should do the right thing with it.
Related
I need to write a little Grails (or Java) app that will handle authentication (from our proprietary Single Sign On system) and then once authenticated allow a user to download files. This is very straight forward if I simply include the files in the WAR file of the application, however, I'd like to avoid that since there will be multiple files and I'd rather not have to upload a new WAR file every time we add a new file. Is it possible to accomplish this by having the application be in a WAR file but the files outside the WAR file, if so, how do I configure this kind of setup? We'll be running this on Tomcat.
Yes this is possible. Without knowing all your requirements or what you have tried and why it didn't work work for you the best I can do is give you a general idea of how to accomplish this.
Have a controller that takes an ID of the file that you want the user to download. Based on this key find the associated Domain instance. The domain should store the file name of the file. Then use this file name to resolve the file from the local file system (path configured in your application configuration). Open the file and stream the contents to the browser. Be sure to set he headers correctly to indicate the file name and size.
There are a lot of moving parts involved here but it can be done. Now, if you get stuck on something I suggest you post what you have tried and what's not working about it. Otherwise, the best we/I can do is give you general guidance/advice.
Hope this helps!
Edit
The real key is going to be in the controller for downloading the files. Here is a quick snippet of what that may look like:
String fileName = "something.zip" // should come from your domain instance
String filePathAndName = "/downloads/${fileName}" // should come from your configuration
response.setContentType("application/octet-stream")
response.setHeader("Content-disposition", "attachment;filename=${fileName")
// this will actually buffer/stream the file in 8k chunks instead of reading the entire file into memory.
org.apache.commons.io.IOUtils.copy((new File(filePathAndName)).openStream(), response.outputStream)
response.outputStream.flush()
response.outputStream.close()
So I'm writing a Spring web application that runs some scripts on the local server using ProcessBuilder. That part seems to be running fine. The scripts generate output files and then zip them up into a single .zip file. I'd like to provide the user with a way to download these files but I'm not sure of the best way to do this, or even how to implement any way to do it.
I tried putting the path to the directory into the URL, but I believe since Spring intercepts all URLs and it doesn't know how to process the one pointing at either the directory the Zip is in or the Zip itself, I just get an error. What would the proper way to do this be? Either to display a list of files or just link to the files themselves? Any help would be really appreciated, thank you.
The way you do any file download from a web-app is to write a servlet that writes the content of the file to the http response's output stream. There's an example of this here that's downloading an Excel file.
The directory listings that you get in a web-page don't just happen automatically, you'll have to write a JSP that displays the directory listing with hyperlinks on each file that link to file download servlet.
I looked around and could not find a complete directory listing example for spring. Though it is relatively simple to implement I put together a blog post to explain this, so that it could be quickly reused when needed http://krishna-passionatelycurious.blogspot.com/2013/04/file-download-page-using-spring.html.
But, the overall approach is to loop through the contents of a directory and generate appropriate links, such that the links point back to the same spring handler, where we could make a decision based on whether the accessed link actually points to a directory or a file and generate directory listing again or stream the content for download.
The blog has a sample implementation of this.
As i know it returns the application path? But what exactly the use of it.
In many environments the application user is not allowed to read any files outside of the deployment directory. This is mostly done for security purposes - for example if someone hacks your application they won't be able to read a passwords file.
And in professionally managed environments developers often don't have a say in which directory the application will be placed.
So if you need to read a file like properties, images, certificates, etc. you can place it in the application directory (or .war file) and use getRealPath("") to get the path you need to load.
As an alternative you can place the external files on the classpath but there are sometimes issues with this. For large files most app servers will try to load the entire file into memory and cache it if it is on the classpath.
The getRealPath() gives the absolute path (on the file system) leading to a file specified in the parameters of the call. It returns the path in the format specific to the OS.
The getContextPath() on the other hand returns the URI or the relative path to the resource.
As far as I remember, I've used it to save images or other data files, since it allows you to see where your application is deployed at the moment. For example, Eclipse and Tomcat will create a temporary folder that's buried deep somewhere within your Eclipse profile and deploy the app there.
This is a real path in file system.
From javadoc:
The real path returned will be in a form appropriate to the computer and operating system on which the servlet container is running, including the proper path separators. This method returns null if the servlet container cannot translate the virtual path to a real path for any reason (such as when the content is being made available from a .war archive).
I think it is very clear. Why do we need this? Sometimes web applications perform some manipulation in file system. For example read stuff from files, write files etc. This API allows you to access the place where your JSPs and other stuff is really stored.
I'm using the Netbeans IDE, and I'm currently using a GlassFish server.
What I want to do is write to a file.
I looked at some pages, and the code I have now (that is not working as far as I know) looks like:
File outputFile = new File(getServletContext().getRealPath("/")
+ "TheFile.txt");
FileWriter fout = new FileWriter(outputFile);
fout.write("The Content");
fout.close();
This is my project's structure:
Also where will the file get placed?
Edit:
I forgot to mention there are some other folders below the ones in the picture: Test Packages, Libraries, Test Libraries and Configuration Files. However I don't think the file would get placed there.
Edit (newest):
I found out the file is stored in the /build/web folder, but this is not appearing in Netbeans. Even after I restarted it.
As you've coded, the file will be placed in public web root. That's where getRealPath("/") will point to. To be precise, it's the folder named Web Pages as in your screenshot. As an exercise, do the following to figure the absolute path, so that you can find it by OS disk explorer.
System.out.println(file.getAbsolutePath());
I don't do Netbeans, but likely you need to refresh the folder in your IDE after the write of the file so that it appears in the listing in the IDE. Click the folder and press F5. This is at least true for Eclipse.
That said, this approach is not recommended. This won't work when the servletcontainer isn't configured to expand the WAR on disk. Even when it did, you will lose all new files and changes in existing files when the WAR is been redeployed. It should not be used as a permanent storage. Rather store it on a fixed path outside the webapp or in a database (which is preferred since you seem want to reinvent a CMS).
Note that this is in no way guaranteed to work in all web containers or through restarts and will most likely be overwritten by a redeployment.
If you want to be able to allow your user to update content, you need to store the new content somewhere and have a servlet or a JSP-page or a facelet retrieve the new content from the backing storage and send it to the browser.
See the documentation for getRealPath. It returns you the location on the disk for something specified with a URL.
I'm guessing your file is in the root of your web application on the disk within Glassfish (where the WAR file is extracted). I don't know enough about Glassfish to say where that will be.
Also, note you are using string concatenation to create the file name, so if the getRealPath call doesn't return a String with a "/" on the end, then you might be creating a file in the parent directory of your web app. Perhaps best to use a File object for the parent directory when creating the File object for the actual file. Check out the File API.
I'd recommend creating the file outside of your web app. If you redeploy your WAR file then you might delete your file, which probably isn't what you want.
Being in a servlet makes little difference to the fact that you want to output a file. Just follow the standard file APIs as a starting point. Here's a tutorial.
I have been using tomcat for sometime and still can't find a good way to do file upload. Just wonder how you guys handle file upload.
You know how you can create a symlink in the application to another fs. but then by default tomcat removes your symlink and everything within the symlink. so this add extra steps to auto deployment. I know there are patch that you can change the behavior. but that will make add extra steps to tomcat upgrade, and patch might not be available always.
I use fckeditor(with it's servlet connectors), spring, struts 1/2 and sometime just plain servlet for the fileupload.
What is the best way to do this?
Another requirement is, uploaded file should be viewable and in a nice location so that backup script can backup easily, ideally not within the apps (or just a symlink within the apps)
Any comment is welcome!
=)
Personally, I place the files in a location relative to $CATALINA_BASE:
File dir = new File(System.getProperty("catalina.base"), "uploads");