【SpringMVC】(九)拦截器

拦截器

1.环境配置

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">

    <!--1. 注册DispatcherServlet-->
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <!--关联一个springmvc的配置文件：【servlet-name】-servlet.xml -->
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springmvc-servlet.xml</param-value>
        </init-param>
        <!--启动级别-1-->
        <load-on-startup>1</load-on-startup>
    </servlet>

    <!-- / 和/* 的区别-->
    <!-- / 匹配所有的请求:(不包括.jsp)-->
    <!-- /* 匹配所有的请求：(包括.jsp)-->
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>


    <!--SpringMVC提供的乱码过滤器-->
    <filter>
        <filter-name>encoding</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>utf-8</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>encoding</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
</web-app>

springmvc-servlet.xml

<?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: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
       https://www.springframework.org/schema/context/spring-context.xsd
       http://www.springframework.org/schema/mvc
       https://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <!--自动扫描包，让指定包下的注解生效，由IOC容器统一管理-->
    <context:component-scan base-package="com.musecho.controller"/>

    <!--视图解析器ViewResolver：解析DispatcherServlet传递来的ModelAndView-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="InternalResourceViewResolver">
        <!--前缀-->
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <!--后缀-->
        <property name="suffix" value=".jsp"/>
    </bean>


    <!--JSON乱码问题配置-->
    <mvc:annotation-driven>
        <mvc:message-converters register-defaults="true">
            <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                <constructor-arg value="UTF-8"/>
            </bean>
            <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
                <property name="objectMapper">
                    <bean class="org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean">
                        <property name="failOnEmptyBeans" value="false"/>
                    </bean>
                </property>
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>

   

</beans>

2. 拦截器

springmvc-servlet.xml增加配置

 	<!--拦截器配置-->
    <mvc:interceptors>
        <mvc:interceptor>
            <!-- /**指的是包括这个请求下面的所有请求-->
            <mvc:mapping path="/**"/>
            <bean class="com.musecho.interceptor.MyInterceptor"/>
        </mvc:interceptor>
    </mvc:interceptors>

测试用控制器

//测试拦截器的控制器
@Controller
public class InterceptorController {

    @ResponseBody
    @RequestMapping("/test")
    public String test() {
        System.out.println("正在执行控制器的test方法");
        return "hello";
    }
}

拦截器需要实现接口HandlerIntercptor

//拦截器
public class MyInterceptor implements HandlerInterceptor {

    //返回true：执行下一个拦截器，且放行
    //返回false：不执行下一个拦截器，且不放行
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("=============处理前=============");

        return true;
    }

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

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

输出

3. 实现功能：登录拦截

有main主页和login页面。只有用户登陆后才可以访问main主页，并显示用户名字段。否则拦截，并跳转至login页面。

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>$Title$</title>
</head>
<body>
<a href="${pageContext.request.contextPath}/user/goLogin">登录</a>
<a href="${pageContext.request.contextPath}/user/goMain">首页</a>
</body>
</html>

LoginController

@Controller
@RequestMapping("/user")
public class LoginController {

    @RequestMapping("/goMain")
    public String goMain() {
        return "main";
    }

    @RequestMapping("/goLogin")
    public String goLogin() {
        return "login";
    }

    @RequestMapping("/login")
    public String login(HttpSession session, String name, String pwd) {
        System.out.println("进入方法login");
        if ("admin".equals(name) && "123".equals(pwd)) {
            session.setAttribute("userName", name);
            return "main";
        }
        return "login";
    }

    @RequestMapping("/logOut")
    public String logout(HttpSession session){
        session.removeAttribute("userName");

        return "login";
    }

}

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>登录</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/user/login" method="post">
    用户：<input type="text" name="name">
    密码：<input type="password" name="pwd">
    <input type="submit" value="提交"/>
</form>
</body>
</html>

main.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>首页</title>
</head>
<body>
<h3>欢迎用户，${userName}</h3>

<a href="${pageContext.request.contextPath}/user/logOut">登出用户</a>
</body>
</html>

拦截器配置，在springmvc-servlet.xml

<mvc:interceptor>
       <mvc:mapping path="/user/**"/>
       <bean class="com.musecho.interceptor.LoginInterceptor" />
</mvc:interceptor>

拦截器LoginInterceptor

//登录拦截器
public class LoginInterceptor implements HandlerInterceptor {
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //1.请求登录时不拦截
        if (request.getRequestURI().contains("login")) {
            return true;
        }

        //2.用户已登录不拦截
        if (request.getSession().getAttribute("userName") != null) {
            return true;
        }

        //3.首次登录不拦截


        //其他时候拦截，并转发
        request.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request, response);
        return false;
    }
}

posted @ 2021-02-24 15:59 musecho 阅读(69) 评论(0) 收藏举报

刷新页面返回顶部

musecho

【SpringMVC】(九)拦截器

拦截器

1.环境配置

2. 拦截器

3. 实现功能：登录拦截

公告