Use custom class loader at compile time

Question

Is it possible to specify a custom classloader for javac (or some alternative java compiler)?

I would love such a feat because it would allow me to compile classes that use classes that are only found by my special class loader.

For the curious: I would write a classloder that connects to the database and creates classes based on the found tables.

Answer 1

When starting javac, you can specify the class loader as follows:

javac -J-Djava.system.class.loader=org.awesome.classloader sourcefile.java 

Answer 2

It may be possible to initialize a custom classloader and then use it when calling the new Java 6 compiler API in javax.tools .

Answer 3

The only thing I know about connecting directly to javac (as executed on the command line) is the annotation handler or through a compiler-specific hack .

Answer 4

Just to expand Michael's answer, if you cannot use Java6, look at the sun. packages - they were always available for java applications and always contained a compiler there, it’s just not standard Java, so you don’t hear too much about it, and the API can change (for example, move it to the javax.tools package!)

Answer 5

Take a look at ClassLoader.defineClass . I myself used it to load plugins into a program I created in which I uploaded a byte file to a new class.

Answer 6

If all classes correspond to the same interface, you can simply specify that at compile time.

If not, then I don’t see what you get without outputting .java database-based files and compiling it.