Options for dynamic compilation in Java 5

Question

Are there any options other than Janino for on-the-fly compiliation and execution of Java code in v5? I know v6 has the Compiler API, but I need to work with the v5 VM.

I essentially need to take a string containing a complete Java class, compile it and load it into memory.

Answer 1

All app servers do this for JSP for ever, so obviously it is possible. Checkout tomcat source code maybe?

Answer 2

Invoking javac programatically:

http://www.juixe.com/techknow/index.php/2006/12/12/invoke-javac-at-runtime/

   com.sun.tools.javac.Main javac = new com.sun.tools.javac.Main();  

   String[] options = new String[] 
   {  
      "-classpath", classpath, "-d", outputDir, filename  
   };

   javac.compile(options);

Answer 3

What you want is something like Janino. We've used it for years. You give it (near standard) code and it gives you the classes so you can use them. It actually has quite a few different modes and supports the 1.5 syntactic sugar and auto-boxing and such.

If you call javac, not only will you have to be ready for anything it does, you'll then have to handle putting the class in the right place or making an additional classloader.

Janino is very easy. It should be exactly what you are looking for.