I have a doubt. I am using javawebstar in a swing project. In my app i have some images that I use to improve the design and a file .xls to show a report. I am using the method getClass().getResource("") to locate the images and I realized that my app try to find the resource in the web server using something like this: jar:http://www... . I thought that all resource would be sought in the local computer where the app was installed. Am I doing something wrong?
The app. will download the resources when needed and cache them on the local disks.
For security reasons the URL shown in the console will always point to the server, even for a trusted app. for which all the resources are cached.
Related
I'm working on a Java web application. As part of this web app, I have a database containing objects with image file paths associated with them. By simply dragging and dropping, I was able to put these images in an images folder in my web server. Their path in Eclipse appears to be src/main/webapp/images.
When I want to access these images in a JSP page, I simply make an img tag with src="/images/fileName.png" and it works perfectly fine.
Here's the issue. I want users to be able to upload their own images to the web server, storing the filenames in the database. I've been looking around for a way to do this, but I'm having trouble finding a detailed answer. What can I use to write the images to that specific folder, images, in my web server? Thanks in advance.
For reference, here is an example of a fileName: /images/propane.png
And here is an example of me calling it in JSP: <img src="/images/propane.png">
I realize this may be a kind of basic question, but I'm really having trouble with getting the image to be stored in that specific directory.
You need to be aware that anything uploaded to src/main/webapp/images will be deleted when you deploy a new version of your application to OpenShift. You can save and serve the images from the OPENSHIFT_DATA_DIR, which is the only directory you can write to that won't be deleted when you redeploy your application. You also need to be aware that the files in OPENSHIFT_DATA_DIR are not shared across gears in a scaled OpenShift application. So if your application is scaled, you need to store user uploaded images somewhere like Dropbox or Amazon S3.
For details on how to serve images from OPENSHIFT_DATA_DIR via your Java application, look at the answer to this question and this OpenShift tutorial.
I created a web application using Java Spring, Hibernate, with JSP's. It's basically a blog I made from scratch, so there's an interface where I can add a new blog post with pictures.
I use Heroku to host and deploy the app.
When I want to post images in a blog post, I do:
And that image is currently stored in a resource folder right outside of 'WEB-INF'. Except, as I add more blog posts, I will have a lot of large sized pictures. I don't know where I should store these images and how I should access it. I thought of storing it in the file system, but wouldn't I have to re-deploy the app on heroku each time I add more images? Another option was having a public dropbox folder and linking the images there, but that would open up my entire dropbox directory to the public. Is there a better way to do all of this, especially managing so many large pictures?
Saving files in file system is not a scalable solution. If you add new servers for your web app the images won't be displayed correctly for any request.
You have to save your images in a distributed environment. It can be a LOB column on the database (Postgres for example) or an Amazon S3 storage system.
The access type is very different but both systems are a good option for your images. If they are big in size, S3 is the best option.
Background
I am developing an android application that will only be used on Nexus 7 tablets (my team is also providing and has access to the hardware).
Problem
The app needs to be flexible to allow content to be added (by non-tech savvy users) to the app and accessed without an internet connection.
Our Idea
Android devices have a file system. We want to design a file system layout such that the people adding content to the application can drag and drop into the correct folder.
e.g.
AppName
Images
Videos
If the user adds a video to the videos folder of the device under our app, it will show up in the app.
We understand that this could easily go wrong (accidentally delete a folder, etc.) but this is out best attempt to solve this without having to update the app ourselves whenever new content comes up (and remember, no internet connection!).
The Question
Is it possible to access the android file system contents and insert them into an app as described in the "Our Idea" section? If so, how?
Yes. This is possible if you don't bother about content security. You can copy the content to any of the file system path in sdcard and your app can look for the folder and read the files .
Example , you can create a folder in sdcard as
sdcard/appname/media/
and create a layout to access the files in the device, and when user selects the files provide option to copy it to your sdcard/appname path.
Check this link
http://developer.android.com/training/basics/data-storage/files.html
Note : the sdcard path can be accessed if you connect to any external system ( PC).
I'm working on a FLEX which enables the user navigate through a list of images at the server (BalzeDS tomcat 4.0.0.14931). The images stored under the "WebContent/Images", and the already available/ saved images are displayed as desired.
From this app user would be able to select a file from their local directory and upload it. I have done the necessary coding related with uploading the image and it successfully creates a copy at the desired folder at the server. Once the image file is uploaded I'm trying to display the it at the FLEX end, but the image is not displayed. When check at the target folder at the server end, the file has been created successfully.
In order to make the uploaded image visible, the BlazeDS Tomcat server has to be restarted. Since this is not desired way to go ahead, I am seeking some help from you experts out there to resolved this.
I tried searching the net get this issue sorted out, but unable to come cross any solution. An identical issue was posted on another forum (Tomcat restart problem), that also still not resolved.
I this is best approach to achieve this JAVA/ BlazeDS/ TomCat/ FLEX environment or is there a better alternative. The other alternative I could achieve this is through persisting the file into the database as byte[], but I did not want accomplish in that manner since size of the database tend to shoot up.
I would really appreciate if you could help me out on this.
Thanks in advance.
If you have to restart Tomcat, that means you are storing user data in your web-apps directory. You should not be storing any user data in the webapps folder. These are considered "system files" and should not be publicly editable under any circumstance.
Store any user data in a publicly accessible folder with the correct permissions and serve them over HTTP (you should be able to view it in a web browser).
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.