Dynamic Class Loading in GCJ

Dynamic Class Loading in GCJ

[Tushar kant]

Hi! I'm writing an application in Java  using GCJ and would like to
add a plug-in feature to it. I have searched the internet a lot but
couldn't find a way to dynamically load .class\.so files dynamically.
I would really appreciate it if someone could help me on this.

Re: Dynamic Class Loading in GCJ

[BGB]

----- Original Message ----- 
From: "Tushar kant" <tusharkant15@gmail.com>
To: <java@gcc.gnu.org>
Sent: Thursday, December 25, 2008 11:18 AM
Subject: Dynamic Class Loading in GCJ


> Hi! I'm writing an application in Java  using GCJ and would like to
> add a plug-in feature to it. I have searched the internet a lot but
> couldn't find a way to dynamically load .class\.so files dynamically.
> I would really appreciate it if someone could help me on this.
>

I don't know the details (not being a Java developer), but I think there is 
something for this in the class library somewhere (I don't know if in 
general, or VM specific).

Re: Dynamic Class Loading in GCJ

[Andrew Haley]

Tushar kant wrote:
> Hi! I'm writing an application in Java  using GCJ and would like to
> add a plug-in feature to it. I have searched the internet a lot but
> couldn't find a way to dynamically load .class\.so files dynamically.
> I would really appreciate it if someone could help me on this.

Here's a really simple example:

foo.java:

import java.net.*;

public class foo
{
  public static void main(String[] argv)
    throws Exception
  {
    ClassLoader l
      = (new URLClassLoader
	 (new URL[] {new URL("gcjlib://"
			     + System.getProperty("user.dir")
			     + "/libpop.so")}));
    Class<?> C = l.loadClass("pop");
    C.newInstance();
  }
}

pop.java:

public class pop
{
  pop()
  {
    System.out.println("Cooee!");
  }
}

 $ gcj foo.java  -o foo --main=foo
 $ gcj -findirect-dispatch -Wl,-Bsymbolic -shared pop.java -o libpop.so -fpic

 $ ./foo
Cooee!

Gcj has lots of other class loading mechanisms that you might find useful.
All this, and more, is explained in the gcj documentation.

Re: Dynamic Class Loading in GCJ

[David Daney]

Tushar kant wrote:
> Hi! I have searched the Internet a lot but I just don't seem to find a
> way to dynamically load .so files in gcj. I am writing an application in
> java and I want it to be able to load external plugins during execution
> time. I would appreciate it if some one could help me out on this
> problem.

Ask over on java@ (CCed here).

It should work for many things.  If you have specific problems, we may 
be able to help.

David Daney