【Java】SpringMVC攔截器

1.定義攔截器

• 實現HandlerInterceptor接口
• 繼承HandlerInterceptorAdaptor類

2.攔截器方法

• preHandle：攔截於請求剛進入時，進行判斷，需要boolean返回值，如果返回true將繼續執行，如果返回false，將不進行執行。
• postHandle：攔截於方法成功返回後，視圖渲染前，可以對modelAndView進行操作。
• afterCompletion：攔截於方法成功返回後，視圖渲染前，可以進行成功返回的日誌記錄。

3.攔截器配置

    <mvc:interceptors>
        <mvc:interceptor>
            <!-- 配置攔截URL -->
            <mvc:mapping path="/*"/>
            <!-- 配置攔截器實現類 -->
            <bean class="Interceptor"></bean>
        </mvc:interceptor>
    </mvc:interceptors>

4.登錄校驗的實現

//AuthcInterceptor.java - 攔截器實現
public class AuthcInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        String uri = request.getRequestURI();
        System.out.println("已進入攔截器,攔截URL: " + uri);
        //如果匹配上URI中存在login,即不攔截該請求
        if (uri.matches(".+login$")) {
            return true;
        }
        User c_user = (User) request.getSession().getAttribute("USER_SESSION");
        if (null != c_user) {
            return true;
        }
        response.sendRedirect("../");
        return false;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }

}

// UserController.java - 實現用戶登錄的controller
@Controller
@RequestMapping("/user")
public class UserController {

    @Autowired
    IUserService userService;

    @RequestMapping(value = "/login", method = RequestMethod.POST)
    @ResponseBody
    public Result login(@Valid User user, BindingResult bindingResult, @ApiIgnore HttpSession session) {
        if (bindingResult.hasFieldErrors()) {
            for (FieldError error : bindingResult.getFieldErrors()) {
                return ResultGenerator.genFailResult(error.getDefaultMessage());
            }
        }
        User c_user = userService.login(user);
        if(null == c_user) {
            return ResultGenerator.genFailResult("該用戶不存在");
        }
        session.setAttribute("USER_SESSION", c_user);
        return ResultGenerator.genSuccessResult();
    }

    @RequestMapping(value = "/logout", method = RequestMethod.GET)
    public String logout(HttpSession session) {
        //用戶正常退出，銷燬session對象
        session.invalidate();
        return "redirect:login";
    }
}

<!-- spring-mvc.xml - 攔截器的配置 -->
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/mvc
       http://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <mvc:interceptors>
        <mvc:interceptor>
            <!-- 攔截對象是方法 -->
            <mvc:mapping path="/user/**"/>
            <bean class="cn.edu.yau.interceptors.AuthcInterceptor"></bean>
        </mvc:interceptor>
    </mvc:interceptors>

</beans>