Develop Reference

Accessing internals of a running applet

This might sound like a ridiculous question, but I have to ask it because I have a working product which is doing this.
I have an applet running inside a browser. This applet is just not just any applet, but a fairly complex package application for CRM/ERP. I was told by a vendor company that they are able to monitor what a user does inside the applet, by replacing applet's main class at runtime before launch with their own. The term used was "endorsing".
I am a bit clueless now. How can you look inside an applet and listen on user clicks and keyboard events, even if you could somehow hack into it? I can tell you that this is a true story, because I have seen this vendor company's applicaiton and it just sits in the background and records all the contextual information (for instance, user filled which textbox in the applet, the name of the textbox and etc).
Are they any hacks at classloading level (I feel stupid asking this), or something else that I have not come across in java that would let you do something 'urban legendary' like this?

Java Applets are loaded using a HTML tags like this:
<applet archive="ApplicationSP1.jar,Application.jar" code="Main.class" name="myApp" width="800" height="600"></applet>
As you can see, the "archive" attribute supports several .jar files.
You could use this technique to load your own versions of the Java Classes of the application by putting them in the ApplicationSP1.jar file. They will be loaded before those classes stored in the second Application.jar.
Obviously, you would need to do some reverse engineering to understand which classes from the original application to override or wrap. Then you have to create new ones named exactly (same package and class name) as those you want to override.
Other option would be developing Aspects to capture events in the application and load these aspects using same technique of multiple .jar in the archive attribute of the HTML applet tag.

The solution for capturing Swing/AWT event can be found in
Want javax.swing hook that tells me WHICH component in the hierarchy is executing an action
It is difficult for overwriting Swing/AWT class used by applet which launching from browser.
They have to breaking the protection of Java security manager and get writing permission of JRE endorsed library folder.
For this case, Java Endorsed Standards Override Mechanism is hard to implement without manually operation of end user.

How to open all files extensions in java? [duplicate]

I am displaying a list of files; i.e. xls, doc, pdf, odt etc., in my Java application (Eclipse RCP). When the user clicks on the file, I want to launch the appropriate (according to what the OS thinks) native application, just like it happens in Windows Explorer or the Finder.
And while I am here: It would be nice to also display the same icons that Finder or Explorer use for the different file types.
Is there a library or Eclipse plugin for this?

What you want is java.awt.Desktop:
Desktop.getDesktop().open( file );

I have found an API in Eclipse's SWT now that seems to do the trick:
org.eclipse.swt.program.Program "provides access to facilities for discovering operating system specific aspects of external program launching."
It has methods to find the program for a given file extension, get the program's icon, and even launch the program.

Sounds like you're after the Java Activation Framework ("JAF"). This API lets you determine what files are and what actions you can do on them. Or alternatively the Java Desktop Integration Component ("JDIC"). JDIC allows you to create and no doubt query file associations.
Both projects seem to be in a semi-abandoned state howeer (sigh). But that's par for the course for Sun these days. Only other thing I know of is some Windows specific third party library that's based on JNI called Winpack. It does a bunch of other things too.
You can get the associated icon using the FileSystemView class (Java 1.4+).

JSP Limit the directories of a File Open dialog

I am currently coding a program using the language JSP. I was wondering if/how you would restrict the directories a File Open dialogue box can browse, for instance:
The default directory is in C:/userFiles/username/ I want the user to be able to browse files in that /username/ directory, or directories within that directory, but not any directories above like C:/, or C:/userFiles. I have done some research, and I could not come across an answer. Is this possible with JSP, HTML, or Java and if so, how would I do it? I would prefer JSP or HTML.
Additional Info:
The dialogue box would browse files on a remote server, not on the user's computer.

The File Open dialog is on the client machine and is part of the operating system. You cannot change its behaviour.
In order to list files on a SERVER you would not use a File Open dialog, you'd be turning the list of files into HTML and serving that to the browser. Since you're the one writing the server-side code, you are ALREADY the one in control over which files make it into that list in the first place.
Saying you'd prefer "JSP or HTML" is a pretty good indicator that you don't fully understand the client-server relationship of the web.

How to associate a file with a program in java

Take notepad for example. You can open a file with notepad (right click and open with, or double clicking on the file if it is already associated with notepad) and it will display the contents of a file. I want to be able to open an xml file with the program that I am writing so that it can do some parsing and give a desired output. What sort of ways are there to do this in java? Do I have to ask for an argument to be passed into the program when it is opened? Would this be easier in C++ or some other language? If you need any further information please let me know -- this was the best way I could come up with to discribe my situation, which may be why my google searches have come up empty. Thank you in advance for your help!

You can associate an extension with a java jar and the file name will be passed as args[0] It doesn't get much simpler than that. I suggest you try it with a "hello world" program. ;)

display the contents of a file ..What sort of ways are there to do this in java?
Install/launch the app. using Java Web Start.
Java Web Start (JWS) is the Oracle Corporation technology used to launch rich client (Swing, AWT, SWT) desktop applications directly from a network or internet link. It offers 'one click' installation for platforms that support Java.
JWS provides many appealing features including, but not limited to, splash screens, desktop integration, file associations, automatic update (including lazy downloads and programmatic control of updates), partitioning of natives & other resource downloads by platform, architecture or Java version, configuration of run-time environment (minimum J2SE version, run-time options, RAM etc.), easy management of common resources using extensions..
Here is a demo. of the JNLP API file services (an API available to JWS apps.) that registers an interest (claims an association with) in the .zzz file-type in the launch file. Associations can also be done programmatically using the IntegrationService of the JNLP API.

Manage State in Desktop Application?

i wonder session between Web Application and Desktop Application.
In web applications we can use Session or cookies(or HTTP Session - Stateful if use EJB), but in Desktop Application how can i manage state of object? (if not use Stateful ), i usually use managed state in text file or xml file, it mean when user login , user information will save in text or xml file for managed state and when user logout, system will delete text or xml file. I need some suggest.

I think that you mix the concepts. You should not need to hold user information for desktop application, because your application has only one user instead of many users of a web application. Your application already knows who is its user..
But if you need to save user preferences about your application, as expressed at previous post , you can use The Preferences api, or just you can save to a text file.

The Preferences API is probably what you're after (I think): java.util.prefs

The java.util.pref.Preferences class, which was added in Java 1.4 is used to store and get persistent (remains on disk between program executions) hierarchical name/values pairs.These preferences are stored in an operating system dependent manner, e.g in the Windows registry or a Mac preferences file.
So by using Preferences API, same thing is going to happen file I/O etc which you are doing already but will be in a better-manageable way.
Instead, if possible you can try using Map, accessed by respective methods for insertion/retrieval of user state through a singleton class.