Subj : Re: creating JS objects in Java...?
To   : netscape.public.mozilla.jseng
From : Igor Bukanov
Date : Fri Feb 18 2005 02:02 am

user@domain.invalid wrote:
> getting there.
> i think i compiled the class, now I have to do something with the bytes 
> I just got back.  Do i need to define my own ClassLoader subclass?

No, you can piggyback on the implementation that Rhino uses internally 
and add something like the following to your code fragment:

ClassLoader parentLoader = ThisClass.class.getClassLoader();
GeneratedClassLoader loader = mJsContext.createClassLoader(parentLoader);
Class mainClass = null;
for (int i = 0; i != objs.length; i += 2) {
     Class cl = loader.defineClass((String)objs[i], (byte[])objs[i + 1]);
     if (mainClass == null) mainClass = cl;
}

The above uses the fact that it is the first class in objs that 
extends/implements superclass/interfaces. It is also important to make 
sure that parentLoader in the above code can be used to access both 
Rhino classes and superclass/interfaces. In your case it would happen 
automatically, but in general this is a thing to watch.

Then you can instantiate MainClass like in:

Module module = (Module)mainClass.newInstance();

Regards, Igor


> 
> here's what i've got so far.  How's it look?
> 
> 
> CompilerEnvirons ce = new CompilerEnvirons();
> ce.initFromContext(mJsContext);
> ClassCompiler cc = new ClassCompiler(ce);
> cc.setMainMethodClass("MyCoolNewClass");
> cc.setTargetExtends(Module.class);
> 
> Class[] interfaces = {NamedObject.class};
> cc.setTargetImplements(interfaces);
> 
> String js = "function 
> Start(){Packages.java.lang.System.err.println(this);} function 
> GetName(){return this.toString();} function GetNamedChild(){return null;}";
> Object[] objs = cc.compileToClassFiles(js, "script", 1, "MyCoolNewClass");
> 
> 
> -denny-
> 
> 
> user@domain.invalid wrote:
> 
>> that's exactly perfect!
>> Thank you!
>>
>> I don't really need the class files as actual files, but maybe it's an 
>> interesting optimization to store them away and use the later...
>>
>> I've been looking at the javadocs and I can see roughly what's going 
>> on.  Are there any examples anywhere where someone is doing this?  I 
>> did a google search and didn't come up with much.
>>
>> thanks again - it's perfect.  now if I can just figure out how it 
>> works...
>>
>> =)
>> -denny-
>>
>>
>>
>>
>> Igor Bukanov wrote:
>>
>>> user@domain.invalid wrote:
>>>
>>>> So, if I use the JavaAdapter to make c new javascript class that 
>>>> inherits from another class an implements a few interfaces, if I use 
>>>> the Rhino API to get a hold of that object in Java, can I use it 
>>>> right then and there as an object of those interface types?  Or do I 
>>>> have to use it as such only in the JS context?
>>>>
>>>> Here's what I want to do:  I have an engine that takes Module 
>>>> objects. Many of these Module objects have been overwritten in Java 
>>>> - EmailModule, etc.  I would like to be able to have the user author 
>>>> his own Module using JavaScript, using, presumably, the JavaAdapter.
>>>>
>>>> This authoring is done in a little gui.  Say that I have an 
>>>> interface Foo which has an method Bar() that I want to overwrite.  
>>>> So, in this gui he writes "function Bar(){print("HelloWorld");}".  
>>>> Now, -in Java- how do I make this Module object with this code 
>>>> overloading the superclass method Bar() such that I then have a Java 
>>>> Module object that I can pass around my Java API?
>>>>
>>>> Basically, I want a Java function (not a JS function) like this:
>>>>
>>>> public Module BuildSubclass(String[] superclasses, String 
>>>> iBarJSCode, String iSomeOtherMethodJSCode,...)
>>>> {
>>>>     Module m = new JavaAdapter(superclasses, iBArJSCode, 
>>>> iSomeOtherMethodJSCode);
>>>>
>>>> return m;
>>>> }
>>>>
>>>> Now I have a Module object that extends or implements an arbitrary 
>>>> number of classes or interfaces and who has various overloaded methods.
>>>>
>>>>
>>>> How do I do this? I would be incredibly grateful for some help.
>>>
>>>
>>>
>>>
>>> Use class compiler,
>>> http://www.mozilla.org/rhino/apidocs/org/mozilla/javascript/optimizer/ClassCompiler.html 
>>>
>>> to compile you class to bytecode sublassing the desired class, load 
>>> the generated bytecode into a class loader and instantiate the 
>>> resulting class.
>>>
>>> Regards, Igor
>>
>>
>>
>

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