I was wondering if it was possible to send information from a java applet to a PHP page (and in the long run, a mysql database) on the click of a button (within the java applet).
Of course, if it's easier to just incorporate the jar file instead of an applet, that's also a possibility, but I just don't know how to do that...
Any ideas?
Yes, you can do that. You'll need to grant the Applet permissions to access the network though. Here's an example.
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First I would like to thank this excellent site for all the help for the developers.
I am facing a problem that I need the user to browse to a specific folder on his/her machine then click the submit button.
I like to get all the filenames and types from this folder and read it in a servlet.
Idon't need upload functionality, I need to read the filenames and types in the selected folder.
Is this possible?
Thanks in advance.
The problem with reading the local file system from a web-page within the browser is the sandbox the browser runs in. Normally, you are not able to get out of that sandbox to read the local file system in such a way.
There are a few way around that, for Java you could use a signed applet, or you could use an signed ActiveX control.
Both shouldn't be that difficult, but the Java applet will have a better support all round, since the ActiveX only works on windows.
It's the signing that will become the real problem though. Is this something in a contained environment, or for the actual internet for everyone there to be able to use?
If it's a contained environment, you might be able to pull it off using a self signed certificate. Else you will need a certificate from an actual certificate authority. These can get pretty expensive.
I have a Java applet embedded into a web page which generates a file that the user must download. I understand there is a way to do this by communicating with a Javascript API.
Could somebody please explain to me how to do it this particular way?
Javascript doesn't allow file saving just yet, and the hacks that "work" need modern browser that understands data URI:s. In that case you would simply send the binary data as base64 and make the browser navigate to the data URI by setting document.location.href = 'data:application/octet-stream...' The download prompt would look like this in firefox:
http://img824.imageshack.us/img824/5080/octetstream.png
Flash allows for real download/save dialogs though so you could also look into that... or find out if java applets have that too.
If the user can be expected to have (or be willing to upgrade to) a Plug-In 2 architecture JRE (e.g. Sun's 1.6.0_10+)1, it is possible to launch the applet using Java Web Start. When an app. is launched using JWS, it can access the JNLP API, that offers file services that allow even sand-boxed code to save information to the local file-system.
Here is a demo of the JNLP files services.
That is if the applet needs to be embedded. JWS could launch applets free-floating since it was introduced in 1.2.
I have exported some Processing code (outputs sensor data to a textbox) to an
applet that includes the .jar and .html files. I have tried to insert this html on a
simple website that I created and the java applet doesn't work. Do I have to somehow
modify the html? I know that the .jar files are already in the same directory and
are referenced appropriately in the exported html code. Is there a better approach
to posting to a website? Thank you
I don't think that it is possible, due to security restrictions on applet communication.
More than likely you will have to write a small client/server program using sockets.
The idea would be to transmit the the output from your locally running client application to your applet(server) which would receive and display the data.
You could use any language with socket support obviously(Flash, PHP, etc.), but I assume you will want to stick with Java.
I am looking for a way to save a couple of files created with JavaScript on the clients computer. I want him to be able to choose a folder (similar to open/save folder dialog), and then write the files there. This obviously requires three things:
Ability to popup such a dialog.
Ability to write on the client's computer (signed applets?)
Some way to interact with JavaScript because it knows the filenames and contents to write.
Is this possible or should I just stop dreaming?
It sure is possible.
One way is to use a signed applet, but if your users are willing to upgrade to Java 1.6.0_10+, a signed applet is not needed. Since 1.6.0_10 (the Next Generation Java Plug-In), JNLP API services are available to embedded applets. Here is a demo. of the JNLP file services.
I see the other reply has already covered the applet/JS interaction.
It is possible with a signed applet.
I'd probably do it the other way around, let the javascript code pass all the data to the applet and the applet should open a FileDialog and write the file.
Calling javascript from java can be achieved via `JSObject, calling Java from Javascript is explained here
If your applet is signed you can do everything that you can do in regular application. You can open "File dialog" but it will be the Java's dialog, not the same that is opened when user pushes "browse" button of tag <intput type"file"/>. Obviously signed applet can perform read and write operations with user's disk.
All applets (either signed or unsigned) may call javascript using JSObject. You just have to say MAYSCRIPT="true" into applet tag.
I think that you cannot open the browser's "file open" dialog applet. Actually you even cannot open it using regular javascript. (I'd be happy to know that I am wrong at this point but I spent some time trying to do this and failed).
Wondering if anyone knows if there is a way to "return" something from a java web start application into the code on the website. For example say the user needed to select a location in the java application. This would then pass the location value back to the code on the webpage (which is php and javascript). I have figured out how to pass arguments into a program, but so far cannot figure out any way to get them out after much googling. Any help would be much appreciated, thanks.
In principle no, since the Webstart application can be running without any Website open at all.
But if your clients use the Java-plugin from 1.6.0_10 or later (and not Safari and some other browsers with special Java-handling), you can use a JNLP-enabled applet, which is able to do the same things as a Webstart application (i.e. loading files and such), and is always bound to a webpage. It then can use the Javascript-bridge, or simply a loadDocument with the right parameters to feed back information.
You can use URL or sockets to connect back to the "same-origin" host. You can also use BasicService to open a web page, possibly from a different server, in a browser (although this shouldn't be used to send information back, as it'll be a GET not a POST).