Invoking javac within an application

Question

I'm trying to track down a JDK 1.0 technology, and am wondering if Sun still supports it.
I'm creating an editor in Java2, and would like to provide the users with the ability to write 'scripts' within the editor. The idea would be that the user could use a edit box to write in pure java, as if they were writing the body of a member function. Then, my editor would take the user's 'script' and generate a secondary .java file that splices the 'script' into the body of a member function. The .class file this .java file generates would then be available to a secondary Java2 program that takes as input the various files that were created by my editor.
I would like to provide some sort of interactive debugging for my user. One way to do this is to have my editor generate the .java file, call javac to compile it, and then report any bugs to the user (after adjusting the line number of the bugs to reflect what the user sees in their script window). One way to do this is to call javac externally and parse it's output, but I'd like a pure java solution.
In the Sun's JDK 1.0, there was a sun.tools.javac.* library, but these seem to have been removed from subsequent distributions. I understand that they're still available, but throw depreciation messages whenever they are called. There is also no mention of it in the JDK 1.4 documentation.
My question is: how do I invoke the javac compiler within Java2, and where can I find the supporting documentation?
A few people on comp.lang.java suggested I use BeanShell, and while it looks like a neat tool, I'm looking for something that will fit into my scheme of dynamically creating new .java files.
Mark McKay
http://www.kitfox.com

Answer 1

I don't have a definitive answer, but a good place to look might be the Ant source code. Ant uses sun.tools.javac.Main extensively.
I have the source on my desktop and took the liberty of copying a portion of the Ant taskdef for compiling with JDK 1.3. The source I've copied from is the org.apache.tools.ant.taskdefs.compiler.Javac13 class. If you look in that class, you'll see the use of other compilers for other versions of Java as well.
sun.tools.javac.Main is in the tools.jar file in your Java distribution.
Hope this helps:
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        // Use reflection to be able to build on all JDKs >= 1.1:
        try {
            Class c = Class.forName ("com.sun.tools.javac.Main");
            Object compiler = c.newInstance ();
            Method compile = c.getMethod ("compile",
                new Class [] {(new String [] {}).getClass ()});
            int result = ((Integer) compile.invoke
                          (compiler, new Object[] {cmd.getArguments()}))
                .intValue ();
            return (result == MODERN_COMPILER_SUCCESS);
        } catch (Exception ex) {
            if (ex instanceof BuildException) {
                throw (BuildException) ex;
            } else {
                throw new BuildException("Error starting modern compiler",
                                         ex, location);
        }