Does anybody actually have any examples of using the OSGi Weaving Hook Service?
I'm doing some test on it .But meet some problem. what I want to do is to modify the bytecode of the class in Bundle. ex: The Bundle A registers the Weaving Hook Service and using the ASM to modify the class in Bundle B.
Bundle A :
import org.apache.felix.ipojo.annotations.Component;
import org.apache.felix.ipojo.annotations.Instantiate;
import org.apache.felix.ipojo.annotations.Provides;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.Opcodes;
import org.osgi.framework.hooks.weaving.WeavingHook;
import org.osgi.framework.hooks.weaving.WovenClass;
@Component
@Provides
@Instantiate
public class TWMethodCallsHook implements WeavingHook {
public void weave(WovenClass wovenClass) {
// TODO Auto-generated method stub
if(inInstrumented(wovenClass.getClassName())){
System.out.println("Instrumenting{}");
System.out.println(wovenClass.getBundleWiring().getBundle().getBundleId());
final ClassReader cr=new ClassReader(wovenClass.getBytes());
final ClassWriter cw=new ClassWriter(cr,ClassWriter.COMPUTE_MAXS);
final ClassVisitor v=new TClassVisitor(cw);
System.out.println(wovenClass.getBytes());
cr.accept(v,Opcodes.ASM5);
byte[]code= cw.toByteArray();
System.out.println(code.toString());
wovenClass.setBytes(cw.toByteArray());
}
}
private boolean inInstrumented(String className) {
return className.contains("people");
}
}
======================
package per.osgi.weavingHookText.Adapter;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
public class TClassVisitor extends ClassVisitor {
private final ClassVisitor cw;
public TClassVisitor(final ClassVisitor cw) {
super(Opcodes.ASM5, cw);
this.cw = cw;
// TODO Auto-generated constructor stub
}
@Override
public void visit(int version, int access, String name, String signature, String superName, String[] interfaces) {
super.visit(version, access, name, signature, name, interfaces);
}
@Override
public MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions) {
if("say".equals(name)){
MethodVisitor mv=cw.visitMethod(access, name, desc, signature, exceptions);
return new TMethodVisitor(mv);
}
return null;
}
}
===================================
package per.osgi.weavingHookText.Adapter;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
public class TMethodVisitor extends MethodVisitor {
public TMethodVisitor(MethodVisitor mv){
super(Opcodes.ASM5,mv);
}
@Override
public void visitCode(){
mv.visitFieldInsn(Opcodes.GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;");
mv.visitLdcInsn("========start=========");
mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V", false);
super.visitCode();
}
}
============================ BUNDLE b
package per.osgi.weavingHookTest.Target;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
public class Target implements BundleActivator {
//public people a=new people();
public void start(BundleContext context) throws Exception {
// TODO Auto-generated method stub
//a.say();
}
public void stop(BundleContext context) throws Exception {
// TODO Auto-generated method stub
}
}
==========================
package per.osgi.weavingHookTest.Target;
public class people {
public void say(){
}
}
================================= I want to insert some code to the Class people.
But Some Error happens. The Bundle B can not start ... I want to know actually what happens...
Actually I don't whether it is possible to insert the code to the another BUNDLE
[The console][1]
[The Error][2]
Instrumenting{}
16
[B@2269ab25
[B@6192f5fb
gogo: BundleException: Error starting module.
Thank you for your help.
When I start the budnle B .SOMEING HAPPENS. [1]: https://i.stack.imgur.com/SRPvH.png [2]: https://i.stack.imgur.com/EnrrD.png
