Spring MVC 拦截器的实现

2.拦截器的实现？

  1）首先定义一个类，该类需要继承自HandlerInterceptor接口。

public class UserInterceptor implements HandlerInterceptor {

 

@Override

public void afterCompletion(HttpServletRequest arg0,

HttpServletResponse arg1, Object arg2, Exception arg3)

throws Exception {

// TODO Auto-generated method stub

}

 

@Override

public void postHandle(HttpServletRequest arg0, HttpServletResponse arg1,

Object arg2, ModelAndView arg3) throws Exception {

// TODO Auto-generated method stub

}

 

@Override

public boolean preHandle(HttpServletRequest arg0, HttpServletResponse arg1,

Object arg2) throws Exception {

// TODO Auto-generated method stub

HttpSession session = arg0.getSession();

if(session.getAttribute("user")==null){

return false;

}else{

    return true;

}

}

2）配置拦截器：在springmvc.xml中配置：特别需要注意在springmvc的声明里需要更改，更改之后的配置信息如下：

<beans xmlns="http://www.springframework.org/schema/beans"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xmlns:context="http://www.springframework.org/schema/context"

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/context

        http://www.springframework.org/schema/context/spring-context.xsd

        http://www.springframework.org/schema/mvc

        http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd"

        default-autowire="byName"

        >

3）编写相应的拦截器的拦截路径，在springmvc.xml中配置如下：

<mvc:interceptors>

 <!--使用bean定义一个Interceptor，直接定义在mvc:interceptors根下面的Interceptor将拦截所有的请求  -->

<mvc:interceptor>

    <mvc:mapping path="/admin/*.action"/>  

    <bean class="com.gxa.bj.interceptor.UserInterceptor">

    </bean>

</mvc:interceptor>

</mvc:interceptors>

注意：黄色的这部分的路径配置，表示的是拦截器拦截的是这个路径下的。*表示任意的。

4）示例，比如现在做一个AdminUser的控制器，需要由拦截器来拦截该控制器。

@Controller

@RequestMapping(value="/admin")

public class AdminUserAction {

   @RequestMapping(value="/user.action")

   public void user(){

   System.out.println("请求过来了");

   }

   @RequestMapping(value="/delete.action")

   public void delete(){

   System.out.println("删除的请求");

   }

}

5）如果做的是必须登录之后才能访问的拦截器：

在拦截器里的preHandle方法里：

@Override

public boolean preHandle(HttpServletRequest arg0, HttpServletResponse arg1,

Object arg2) throws Exception {

// TODO Auto-generated method stub

HttpSession session = arg0.getSession();

if(session.getAttribute("user")==null){

arg0.getRequestDispatcher("../login.jsp").forward(arg0,arg1);

return false;

}else{

    return true;

}

}