//json
	@RequestMapping(value = "/json.action" )
	public @ResponseBody Items jsonAction(@RequestBody Items items) {
		return items;
	}

public class HandlerInterceptor1 implements HandlerInterceptor {
	// controller执行后且视图返回后调用此方法
	// 这里可得到执行controller时的异常信息
	// 这里可记录操作日志
	@Override
	public void afterCompletion(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, Exception arg3)
			throws Exception {
		System.out.println("HandlerInterceptor1....afterCompletion");
	}

	// controller执行后但未返回视图前调用此方法
	// 这里可在返回用户前对模型数据进行加工处理，比如这里加入公用信息以便页面显示
	@Override
	public void postHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, ModelAndView arg3)
			throws Exception {
		System.out.println("HandlerInterceptor1....postHandle");
	}

	// Controller执行前调用此方法
	// 返回true表示继续执行，返回false中止执行
	// 这里可以加入登录校验、权限拦截等
	@Override
	public boolean preHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2) throws Exception {
		System.out.println("HandlerInterceptor1....preHandle");
		// 设置为true，测试使用
		return true;
	}
}

package my.study.springmvc.controller;


import javax.servlet.http.HttpSession;

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

@Controller
@RequestMapping(value = "/user")
public class UserController {

	/**
	 * 跳转到登录页面
	 * 
	 * @return
	 */
	@RequestMapping("toLogin")
	public String toLogin() {
		return "login";
	}
	/**
	 * 用户登录
	 * 
	 * @param username
	 * @param password
	 * @param session
	 * @return
	 */
	@RequestMapping("login")
	public String login(String username, String password, HttpSession session) {
		// 校验用户登录
		System.out.println(username);
		System.out.println(password);

		// 把用户名放到session中
		session.setAttribute("username", username);

		return "redirect:/item/itemList.action";
	}
}

package my.study.springmvc.Interceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

public class LoginHandlerInterceptor implements HandlerInterceptor {

  //...省略部分代码

	@Override
	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object arg2) throws Exception {
		// 从request中获取session
		HttpSession session = request.getSession();
		// 从session中获取username
		Object username = session.getAttribute("username");
		// 判断username是否为null
		if (username != null) {
			// 如果不为空则放行
			return true;
		} else {
			// 如果为空则跳转到登录页面
			response.sendRedirect(request.getContextPath() + "/user/toLogin.action");
		}

		return false;
	}
}