import static org.objectweb.asm.Opcodes.ACC_PUBLIC;
import static org.objectweb.asm.Opcodes.ACC_STATIC;
import static org.objectweb.asm.Opcodes.ACC_SUPER;
import static org.objectweb.asm.Opcodes.ALOAD;
import static org.objectweb.asm.Opcodes.ILOAD;
import static org.objectweb.asm.Opcodes.INVOKESPECIAL;
import static org.objectweb.asm.Opcodes.IRETURN;
import static org.objectweb.asm.Opcodes.MH_INVOKESTATIC;
import static org.objectweb.asm.Opcodes.RETURN;
import static org.objectweb.asm.Opcodes.V1_7;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;
/**
* Modified from the code published by Remi Forax, as attachment to this blog
* post:
* <http://weblogs.java.net/blog/forax/archive/2011/01/07/call-invokedynamic
* -java>
*
* @author Attila Szegedi
*/
public class DynamicIndy extends ClassLoader {
private int ID_GENERATOR = 0;
public MethodHandle invokeDynamic(String name, MethodType desc, Class<?> bsmClass, String bsmName, MethodType bsmType, Object... bsmArgs) {
ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES);
cw.visit(V1_7, ACC_PUBLIC | ACC_SUPER, "Gen"+(ID_GENERATOR++), null, "java/lang/Object", null);
MethodVisitor init = cw.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null);
init.visitCode();
init.visitVarInsn(ALOAD, 0);
init.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "<init>", "()V");
init.visitInsn(RETURN);
init.visitMaxs(-1, -1);
init.visitEnd();
String descriptor = desc.toMethodDescriptorString();
MethodVisitor mv = cw.visitMethod(ACC_PUBLIC|ACC_STATIC, "invokedynamic", descriptor, null, null);
int slot = 0;
for(Type parameterType: Type.getArgumentTypes(descriptor)) {
mv.visitVarInsn(parameterType.getOpcode(ILOAD), slot);
slot += parameterType.getSize();
}
mv.visitInvokeDynamicInsn(name, descriptor,
new org.objectweb.asm.MethodHandle(MH_INVOKESTATIC,
bsmClass.getName().replace('.', '/'),
bsmName,
bsmType.toMethodDescriptorString()),
bsmArgs);
Type returnType = Type.getReturnType(descriptor);
mv.visitInsn(returnType.getOpcode(IRETURN));
mv.visitMaxs(-1, -1);
mv.visitEnd();
cw.visitEnd();
byte[] array = cw.toByteArray();
Class<?> clazz = defineClass(null, array, 0, array.length);
try {
return MethodHandles.lookup().findStatic(clazz, "invokedynamic", desc);
}catch (IllegalAccessException|NoSuchMethodException e) {
throw (AssertionError)new AssertionError().initCause(e);
}
}
}