public interface UserService {
  public void addUser();
  public void removeUser();
  public void searchUser();
}

public class UserServiceImpl implements UserService {
  public void addUser() {
    System.out.println("add user");
  }
  public void removeUser() {
    System.out.println("remove user");
  }
  public void searchUser() {
    System.out.println("search user");
  }
}

public class TransactionInterceptor implements InvocationHandler {

  private Object target;

  public void setTarget(Object target) {
    this.target = target;
  }
  
  @Override
  public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
    System.out.println("start Transaction");
    method.invoke(target, args);
    System.out.println("end Transaction");
    return null;
  }

}

public class TestDynamicProxy {

  @Test
  public void testJDK() {
    TransactionInterceptor transactionInterceptor = new TransactionInterceptor();
    UserService userService = new UserServiceImpl();
    transactionInterceptor.setTarget(userService);
    UserService userServiceProxy =
        (UserService) Proxy.newProxyInstance(
            userService.getClass().getClassLoader(),
            userService.getClass().getInterfaces(),
            transactionInterceptor);
    userServiceProxy.addUser();
  }

}

start Transaction
add user
end Transaction

public class UserServiceCallBack implements MethodInterceptor {

  @Override
  public Object intercept(Object o, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {
    System.out.println("start Transaction by cglib");
    methodProxy.invokeSuper(o, args);
    System.out.println("end Transaction by cglib");
    return null;
  }

}

public class TestDynamicProxy {

  @Test
  public void testCGLIB() {
    Enhancer enhancer = new Enhancer();
    enhancer.setSuperclass(UserServiceImpl.class);
    enhancer.setCallback(new UserServiceCallBack());
    UserServiceImpl proxy = (UserServiceImpl)enhancer.create();
    proxy.addUser();
  }

}

start Transaction by cglib
add user
end Transaction by cglib