In a servlet I'm running on GAE, I'm trying to get the screen width in pixels of the device being used so that I can dynamically redirect the user to either the desktop or mobile jsp page. I first tried using the java.awt.Toolkit.getDefaultToolkit().getScreenSize() but receieved the error message: java.awt.Toolkit is not supported by Google App Engine's Java runtime environment. For now, I'm running the screen check in a jsp page using javascript but I'd like to move it to the servlets.
You can't move it to the servlets. The server is not aware of the user's screen or any details besides user-agent and what Javascript provides. You'll need to use Javascript and pass around the screen size in a cookie or in the requests.
java.awt.Toolkit.getDefaultToolkit().getScreenSize()
being run on GAE is not applicable as we don't care about GAE's screen which is nonexistent anyway.
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I am developing an Android application for a facebook page. More specifically I want to display post images as part of a feed. The way I have achieved this thus far is by using restfb along with Graph API, making requests to Graph API, receiving the images and displaying them to the feed.
My concerns are the following:
I heavily rely on the access token facebook gives me for accessing those images and other page data.
Whether, if theoretically the traffic of the application increases, can it be supported by Graph API, both performance-wise and logic-wise(extension of the access token troubles me for multiple devices).
Considering the above I have decided to go with a server-based approach. That means storing just images to the server instead of posting them on facebook. Is there an Android specific approach when building a server? Any specific documentation I should read?
UPDATE:
I decided to go with a Firebase Storage approach where I will upload images to the Storage and download them into my application.
I'm developing an app in which i need to fetch the URL's that are accessed by the user. I've successfully fetched the URL's from android's default browser. I know that some browsers are protective towards this act. But i need to know whether there's any work around that could succeed this objective. Mainly from opera and dolphin browser
I am currently learning JSP and Java Servlets. I was wondering if there is any way to call a java GUI from a JSP, not necessarily to load into the page, but to load onto the screen for database input. I am struggling trying to find some reference on how to do this on the net, but no luck so far.
You could use Java Webstart to start up the application on the client side. Or, ask the user to install a local client differently (like a daemon service).
The "GUI application" must have some kind of RPC (=remote procedure call) service running in background.
Once the client has your gui application installed, the JSP can invoke urls on http://localhost:port (ajax would help sending messages to the GUI application). The GUI application must have some rpc system (rest, webservice) that receives the requests from your web application (your jsp app) and start the GUI requested by the URL.
The problem here is to make sure the client has the port of choice available.
Another possibility is to register some URL to your application in the client side, so that when the user clicks a url like myapp://form/123 the OS automatically invokes your application to handle that URL. This kind of thing must be done differently per operating system. It's the way it works when you click on a magnet link or a skype://link. The procedure to register urls in the operating system is different per OS, you need to do some research (I never did that, but I am sure it is possible). You can also register a file extension to your app, and make sure that the specified extension is registered to your app. When the browser downloads the file and opens it, your app is invoked with the file downloaded as parameter (which will contain the instruction for your GUI). But most browser will not start automatically the app associated to the file after the download: again, you need to do some tricks on the client's operating system to make the "download and open" the default behavior for the browser.
I'm remote controlling a Java application on a PC through an Android phone, and I needed my application to open a browser at the phones command, chrome in this case. I created a "Process" for chrome, opening a certain address. However, I need to be able to give tools on the Android phone for controlling the web page, such as scrolling. Can I programmatically send a command for chrome to scroll from my PC application containing the Process?
Sorry, it may have been unclear, but the only connection the android phone has to the program is through a socket. It is only used as a remote control for another Java application on a PC, which has its own screen.
I do not think that clean solution exists.
But I can suggest the following directions:
(1) try to investigate the native chrome API. If it has such ability call it with JNI.
(2) Try to use class java.awt.Robot. It allows to simulate user's activity, e.g. mouse clicks. Unfortunately it does not allow you to find any window outside your application, so it is a problem to decide where to perform the click.
(3) You can create proxy server and make browser you open to go to the target URL through the proxy. The proxy server will insert into the page your javascript that will communicate with server. The application that opens browser will send commands to server. The javascript that you inserted will receive these commands using AJAX and perform them. JavaScript can scroll browser window, so theoretically you can implement this.
If you can target the tab you want to control and edit the address bar you could send the command 'javascript:scrollTo(x, y)'. I just tested it on this page and it seems to work fine, replacing what I typed with the original address of the page.
Can I programmatically send a command for chrome to scroll from my PC
application containing the Process?
Not directly. What you could do is make some sort of web service that sits between the Android client and page that the Android client can send commands to and the page can periodically poll via AJAX calls to see what the client wants. That would be a clean DIY way that would work on other browsers besides Chrome.
You can use vnc viewer applications for that.
http://code.google.com/p/android-vnc-viewer/
I have a java application that will take the image as an input and output another image. I have a website with a popular host (PHP+MYSQL Hosting). I want to create a page on the website with PHP with a form where a user can upload an image which will then pass the image onto the Java application.
What I am planning on doing is when then user uploads the image, it gets stored in a folder on the web server. I will then call the java app on the server passing the url of the image as an argument and then the java app will output another image, let’s say, to a result folder. The PHP page after the execution will then display the result image on the browser.
Now my questions are:
Is it possible to execute java apps on popular webhosts (for example mine is WebHostingBuzz.com)?
The java app is fairly heavy as it does a lot of image processing. Should I offload the java app to another web server? If yes, are there any services that will run my java app?
(Optional) It’s a demo of my java app and I don’t want to store the images people upload. Is there a way where I can directly pass the uploaded image to the java app and output the image generated directly instead of storing it on the web server? I would prefer this because, if the image is big, I can make PHP stop the execution after a timeout.
How do I communicate with the java app from PHP for info on its execution, for example When PHP calls the java app, the page has to wait till the app finishes processing? I want the java app to send a response to the PHP page saying that the processing is completed and the page is redirected or refreshed accordingly.
I hope you get the idea, please suggest the technologies that I can use to implement this and also if you have a better idea, post it!
Thanks!
Now my questions are: Is it possible to execute java apps on popular webhosts (for example mine is WebHostingBuzz.com)?
It's technically possible. But the hosting has to install JRE at the host and give the PHP user sufficient OS-level and filesystem-level permissions. So you're really dependent on the hosting whether they provide this opportunity. Best is to just contact their support team and ask it.
If it is supported, you could just use shell_exec().
$result = shell_exec("java -jar /path/to/imageprocessor.jar " + $imagepath);
if ($result) {
// Shell execution succeed.
} else {
// Shell execution failed.
}
For asynchronous communication / background processing, the client has to fire an ajaxical request.
If it is not supported, consider porting Java to PHP. The GD image library has pretty a lot of functions which may be of use.
Google App Engine allows to host Java (and Python) web applications. The SDK and the basic account is free of charges. With the SDK, you could develop and test the application locally and then simply deploy to App Engine (NetBeans and Eclipse plugins are available).
Then the PHP app could send the data in a HTTP POST to the Google App Engine application and get the result in the response data.
Or the data is stored first in a database blob and a processing job is put in a task queue (a 'message queue'). This has the advantage that the PHP client request will return immediately after the data has been POSTed. Then, the PHP application could poll for the result data while Google App Engine processes the image. The PHP side would be more responsive this way.
Wouldn't it be easier to make your java app a web app, that PHP could call via an url in wich he would put the url of the image so java can download it?
like http://yourjavaserver/imageprocessing?imgurl=IMAGE_URL
and the java servlet would reply with the image file itlsef.
You can look for "java hosting" on google, to find a host for this, but it's more expensive than PHP hosting. Maybe the best choice would be to get a dedicated server which could host both PHP and java applications...
I think your best bet here is with your java app running as cron(or a deamon) that can load the file details from the database. This will require a (one or more) page-refresh on the users part after the generation is complete, at which point your script can recall the image from the database/filesystem.
I do not think you will be able to do this in real-time due to timeout restrictions on the PHP webpage. However, you could write a java applet that can take the file and process it before sending it to the server (or depending on how you intend to use it, perhaps you do not need to upload it after the transformation?).