springmvc拦截器

用一个例子来说明，一个小网站，只有用户登录后才可访问，否则被拦截。

要定义拦截器，需要实现Spring的HandleIntercetor接口或者继承抽象类HanlerInterceptorAdater

中间有三个方法，通过例子说明：

public class AuthorizationInterceptor implements HandlerInterceptor {
    private static final String[] IGNGRE_URI={"/loginForm","/login"};

    /**
     * 该方法在Controller处理之前执行。当返回值为true才执行controller，否则不执行。
     * @param httpServletRequest
     * @param httpServletResponse
     * @param o
     * @return
     * @throws Exception
     */
    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
        System.out.println("AuthorizationInterceptor preHandle --> ");
        boolean flag=false;
        String servletPath=httpServletRequest.getServletPath();
        for(String s:IGNGRE_URI){
            if(servletPath.contains(s)){
                flag=true;
                break;
            }
        }
        if(!flag){
            User user=(User)httpServletRequest.getSession().getAttribute("user");
            if(user==null){
                System.out.println("AuthorizationInterceptor 拦截请求：");
                httpServletRequest.setAttribute("message","请先登录再访问网站");
                httpServletRequest.getRequestDispatcher("loginForm").forward(httpServletRequest,httpServletResponse);
            }else {
                System.out.println("AuthorizationInterceptor 放行请求：");
                flag=true;
            }
        }
        return flag;
    }

    /**
     * 在controller的方法调用之后执行，方法中可以多modelAndview进行操作
     * @param httpServletRequest
     * @param httpServletResponse
     * @param o
     * @param modelAndView
     * @throws Exception
     */
    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
        System.out.println("AuthorizationInterceptor postHandle -->");
    }

    /**
     * 该方法在整个请求完成之后执行，主要作用是用于清理资源
     * @param httpServletRequest
     * @param httpServletResponse
     * @param o
     * @param e
     * @throws Exception
     */
    public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
        System.out.println("AuthorizationInterceptor afterCompletion --> ");
    }
}

<mvc:interceptors>
    <mvc:interceptor>
        <mvc:mapping path="/*"/>
        <bean class="org.fkit.domain.AuthorizationInterceptor"/>
    </mvc:interceptor>
</mvc:interceptors>

设置拦截所有请求。