import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
public class ASMProxyExample {
public static void main(String[] args) {
cw.visit(Opcodes.V11, Opcodes.ACC_PUBLIC, "com/example/MyProxy", null, "java/lang/Object", new String[]{"my/package/MyInterface"});
MethodVisitor mv = cw.visitMethod(Opcodes.ACC_PUBLIC, "<init>", "()V", null, null);
mv.visitVarInsn(Opcodes.ALOAD, 0);
mv.visitMethodInsn(Opcodes.INVOKESPECIAL, "java/lang/Object", "<init>", "()V", false);
mv.visitInsn(Opcodes.RETURN);
mv.visitMaxs(0, 0);
mv.visitEnd();
mv = cw.visitMethod(Opcodes.ACC_PUBLIC, "myMethod", "()V", null, null);
mv.visitFieldInsn(Opcodes.GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;");
mv.visitLdcInsn("Before method invocation");
mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V", false);
mv.visitFieldInsn(Opcodes.GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;");
mv.visitLdcInsn("After method invocation");
mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V", false);
mv.visitInsn(Opcodes.RETURN);
mv.visitMaxs(0, 0);
mv.visitEnd();
cw.visitEnd();
byte[] bytecode = cw.toByteArray();
MyInterface proxy = (MyInterface) Proxy.newProxyInstance(
ASMProxyExample.class.getClassLoader(),
new Class[]{MyInterface.class},
new InvocationHandler() {
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
return null;
}
}
);
proxy.myMethod();
}
}
interface MyInterface {
void myMethod();
}
