springMVC配置拦截器

﹏ヽ暗。殇╰゛Y 2023-08-17 17:08 108阅读 0赞

1，拦截器的概念  
    java里的拦截器是动态拦截Action调用的对象，它提供了一种机制可以使开发者在一个Action执行的前后执行一段代码，也可以在一个Action执行前阻止其执行，同时也提供了一种可以提取Action中可重用部分代码的方式。在AOP中，拦截器用于在某个方法或者字段被访问之前，进行拦截然后再之前或者之后加入某些操作。目前，我们需要掌握的主要是Spring的拦截器，Struts2的拦截器不用深究，知道即可。  
  
2，实现方法

我们如果在项目中使用了Spring框架，那么，我们可以直接继承HandlerInterceptorAdapter.java这个接口，来实现我们自己的拦截器。

先看看HandlerInterceptorAdapter.java这个抽象类

//
    // Source code recreated from a .class file by IntelliJ IDEA
    // (powered by Fernflower decompiler)
    //
    
    package org.springframework.web.servlet;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public interface HandlerInterceptor {
        //在业务处理器处理请求之前执行
        boolean preHandle(HttpServletRequest var1, HttpServletResponse var2, Object var3) throws Exception;
        //业务处理器处理请求之后，生成视图之前执行
        void postHandle(HttpServletRequest var1, HttpServletResponse var2, Object var3, ModelAndView var4) throws Exception;
        // 在DispatcherServlet完全处理完请求之后被调用，可用于清理资源
        void afterCompletion(HttpServletRequest var1, HttpServletResponse var2, Object var3, Exception var4) throws Exception;
    }

4：自定义拦截器类继承HandlerInterceptorAdapter.java这个接口

package com.yc.interceptor;
    
    import org.springframework.web.servlet.HandlerInterceptor;
    import org.springframework.web.servlet.ModelAndView;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import javax.servlet.http.HttpSession;
    
    /**
     * @author wk
     * @date 2019/9/17  15:29
     */
    public class BackForwardInterceptor implements HandlerInterceptor {
        @Override
        public boolean preHandle(HttpServletRequest httpServletRequest,
                                 HttpServletResponse httpServletResponse, Object o) throws Exception {
            //获取请求的可用地址
            String path = httpServletRequest.getServletPath();
            path = path.substring(path.lastIndexOf("ded")+1);
            HttpSession session = httpServletRequest.getSession();
            //判断用户是否登录
            session.setAttribute("path",path);
            Integer uid =  (Integer)session.getAttribute("user");
            //内部转发
            if (uid != null ) {
                return true;
            }
            // 跳转到登录页面  
                request.getRequestDispatcher("/WEB-INF/login.jsp").forward(request, response); 
            return false;
        }
    
        @Override
        public void postHandle(HttpServletRequest httpServletRequest,
                               HttpServletResponse httpServletResponse, Object o,
                               ModelAndView modelAndView) throws Exception {
    
        }
    
        @Override
        public void afterCompletion(HttpServletRequest httpServletRequest,
                                    HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
    
        }
    }

5，配置springmvc.xml文件即可

<mvc:interceptors>
            <mvc:interceptor>
                
                <mvc:mapping path="/order/findAll"/>
                <mvc:mapping path="/order/add"/>
                <bean class="com.yc.interceptor.BackForwardInterceptor"/>
            </mvc:interceptor>
        </mvc:interceptors>