sprng mvc注解 service注入的问题 求救。。。
最近在学spring mvc ，为新项目做技术储备
折腾了一个星期，总算有点眉目了，今天下午写了个例子，用了三层结构 controller service 还有DAO，但是运行后发现service没有注入，导致项目的功能运行不正常，调了半天还是没有结果。。。各位大神帮忙看看
好了，废话不多说，上代码。。。。

先是controller

package com.itsum.springmvcpt.bg.test.controller;





import java.util.Iterator;

import java.util.LinkedList;

import java.util.List;



import javax.validation.Valid;



import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Controller;

import org.springframework.validation.BindingResult;

import org.springframework.validation.FieldError;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestParam;

import org.springframework.web.servlet.ModelAndView;

import org.springframework.web.servlet.view.RedirectView;



import com.itsum.springmvcpt.bg.test.benas.dtos.User;

import com.itsum.springmvcpt.bg.test.services.Iservices.Iuserservice;

import com.itsum.springmvcpt.bg.test.services.serviceImpl.UserService;





@Controller

public class UserController {

	

	

	private Iuserservice service;

	

	

	public Iuserservice getService() {

		return service;

	}



	public void setService(Iuserservice service) {

		this.service = service;

	}



	@RequestMapping("/welcome")

	public ModelAndView welcome(){

		ModelAndView mv=new ModelAndView();

		System.out.println("service:  "+service);

		List<User> list=service.findByLimit(10);

		mv.addObject("list", list);

		mv.setViewName("welcome");

		return mv;

	}

}

然后是service接口:

package com.itsum.springmvcpt.bg.test.services.Iservices;



import java.util.List;



import com.itsum.springmvcpt.bg.test.benas.dtos.User;



public interface Iuserservice {

	

	public List<User> findByLimit(int limit);

	

}

service实现:

package com.itsum.springmvcpt.bg.test.services.serviceImpl;



import java.util.List;



import javax.annotation.Resource;



import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Service;

import org.springframework.transaction.annotation.Transactional;



import com.itsum.springmvcpt.bg.test.benas.dtos.User;

import com.itsum.springmvcpt.bg.test.dao.Idaos.UserDao;

import com.itsum.springmvcpt.bg.test.services.Iservices.Iuserservice;





@Service("service")

public class UserService implements Iuserservice{

	

	

	private UserDao dao;

	

	public UserDao getDao() {

		return dao;

	}

	public void setDao(UserDao dao) {

		this.dao = dao;