【SSM - SpringMVC篇】拦截器 拦截器interceptor与过滤器filter的区别

拦截器与过滤器的区别

filter:filter，是javaEE 提供的用来拦截请求的，所有请求都能拦截
interceptor:只能拦截控制器DispatcherServlet的方法,让处理器Handler接收不到方法

interceptor拦截器的使用方法

实现HandlerInterceptor接口
覆盖重写方法
prehandle方法的返回值true为放行,false为拦截
配置拦截器

Demo01Interceptor实现一个接口HandlerInterceptor

//1:实现一个接口HandlerInterceptor
public class Demo01Interceptor  implements HandlerInterceptor {
    
    
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
    
    
        System.out.println("preHandle");
        return true;
    }

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

    }

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

    }
}

接口的三个方法的执行顺序

多个拦截器的执行顺序(了解)

springmvc.xml

按照配置的顺序来进行拦截

<!--拦截器使用第二步:配置拦截器-->
    <mvc:interceptors>
        <!--用于测试的拦截器-->
        <mvc:interceptor>
            <!--拦截路径的配置-->
            <mvc:mapping path="/demo05.action"/>
            <bean id="interceptor1" class="com.wzx.interceptor.Demo01Interceptor"/>
        </mvc:interceptor>
        <mvc:interceptor>
            <!--拦截路径的配置-->
            <mvc:mapping path="/demo05.action"/>
            <bean id="interceptor2" class="com.wzx.interceptor.Demo02Interceptor"/>
        </mvc:interceptor>
        <mvc:interceptor>
            <!--拦截路径的配置-->
            <mvc:mapping path="/demo05.action"/>
            <bean id="interceptor3" class="com.wzx.interceptor.Demo03Interceptor"/>
        </mvc:interceptor>
    </mvc:interceptors>

通配符 *

/** 任意目录，任意地址

案例练习

像有些网站必须登录才能看到里面的内容,没有登录的强制跳转到登录页面

springmvc.xml

<!--拦截器使用第二步:配置拦截器-->
    <mvc:interceptors>
        <!--用于测试的拦截器-->
        <mvc:interceptor>
            <!--拦截路径的配置-->
            <mvc:mapping path="/**"/>
            <bean id="interceptor1" class="com.wzx.interceptor.LoginInterceptor"/>
        </mvc:interceptor>

    </mvc:interceptors>

LoginInterceptor

//1:判断一下路径，如果访问的是order address..判断是否登录 未登录强制到登入页面
public class LoginInterceptor implements HandlerInterceptor {
    
    
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
    
    
        System.out.println("LoginInterceptor preHandle------------------------");
        User user = (User) request.getSession().getAttribute("user");
        if(user == null){
    
    
            String address = request.getRequestURI();
            System.out.println("address = "+address);
            if(address.contains("order")||address.contains("address")){
    
    
                String contextPath=request.getContextPath();
                response.sendRedirect(contextPath+"/login.jsp");
                //强制到登录页面
                return false;
            }
        }
        return true;
    }

    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
    
    
        System.out.println("LoginInterceptor postHandle------------------------");
    }

    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
    
    
        System.out.println("LoginInterceptor afterCompletion------------------------");
    }
}

OrderController

@Controller
@RequestMapping("/order")
public class OrderController {
    
    
    @RequestMapping(path = "/query.action",method = {
    
    RequestMethod.GET,RequestMethod.POST})
    public String query(Integer id){
    
    
        System.out.println("你访问了我的订单功能 ");
        return "order";
    }
}