Spring MVC 拦截器 （十）

完整的项目案例： springmvc.zip

目录

实例

除了依赖spring-webmvc还需要依赖jackson-databind（用于转换json数据格式)

<!--json-->
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.9.6</version>
</dependency>


项目结构：

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">

    <!-- 请求总控器 -->
    <servlet>
        <servlet-name>dispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:dispatcher-servlet.xml</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>dispatcher</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

</web-app>

配置dispatcher-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:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

    <context:component-scan base-package="edu.nf.ch10"/>

    <mvc:annotation-driven/>

    <mvc:default-servlet-handler/>

    <!-- 配置拦截器栈 -->
    <mvc:interceptors>
        <!-- 可以配置多个<mvc:interceptor>表示多个拦截器 -->
        <mvc:interceptor>
            <!-- 哪些请求映射到拦截器中 -->
            <mvc:mapping path="/**"/>
            <!-- 排除那些请求不经过拦截器-->
            <mvc:exclude-mapping path="/login.html"/>
            <mvc:exclude-mapping path="/userLogin"/>
            <mvc:exclude-mapping path="/js/**"/>
            <!-- 配置拦截器的bean-->
            <bean class="edu.nf.ch10.interceptors.LoginInterceptor"/>
        </mvc:interceptor>
    </mvc:interceptors>

    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>

</beans>

请求控制器UserController：

package edu.nf.ch10.controller;

import edu.nf.ch10.controller.vo.ResponseVO;
import edu.nf.ch10.entity.Users;
import edu.nf.ch10.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import javax.servlet.http.HttpSession;

/**
 * @author wangl
 * @date 2018/11/5
 */
@Controller
public class UserController {

    @Autowired
    private UserService userService;

    @PostMapping("/userLogin")
    public @ResponseBody ResponseVO login(Users user, HttpSession session){
        user = userService.login(user);
        //只有当会话作用域存在用户信息才表示正常登陆
        session.setAttribute("user", user);
        ResponseVO vo = new ResponseVO();
        vo.setValue("index.html");
        return vo;
    }
}

异常处理类ControllerAdviceHandler：

package edu.nf.ch10.controller.advice;

import edu.nf.ch10.controller.vo.ResponseVO;
import edu.nf.ch10.service.exception.UserException;
import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;

/**
 * @author wangl
 * @date 2018/11/5
 * 定义一个全局的异常处理类（类似一个切面）
 * 这个类中定义的所有方法都是异常处理方法，
 * 也可以理解为是全局的异常通知
 * value属性指定对哪些控制器进行切入拦截
 */
@ControllerAdvice("edu.nf.ch10.controller")
public class ControllerAdviceHandler {

    @ExceptionHandler(UserException.class)
    public @ResponseBody ResponseVO loginExceptionHandle(UserException e){
        ResponseVO vo = new ResponseVO();
        vo.setCode(HttpStatus.UNAUTHORIZED.value());
        vo.setMessage(e.getMessage());
        return vo;
    }
}

登录拦截器 LoginInterceptor

package edu.nf.ch10.interceptors;

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 wangl
 * @date 2018/11/5
 * 登陆拦截器
 * 拦截器必须实现Spring提供的一个HandlerInterceptor接口
 */
public class LoginInterceptor implements HandlerInterceptor {

    /**
     * 在调用Controller的请求方法之前执行
     * @param request
     * @param response
     * @param handler
     * @return
     * @throws Exception
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        HttpSession session = request.getSession();
        //如果session获取的用户信息为null，表示没有登陆
        //那么将重定向到登陆页面
        if(session.getAttribute("user") == null){
            response.sendRedirect("login.html");
            return false;
        }
        return true;
    }

    /**
     * 在调用Controller方法之后执行(注意：只有在preHandle方法返回true的情况下才会执行)
     * @param request
     * @param response
     * @param handler
     * @param modelAndView
     * @throws Exception
     */
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("请求到达方法之后...");
    }

    /**
     * 在视图响应之后执行(注意：只有在preHandle方法返回true的情况下才会执行)
     * @param request
     * @param response
     * @param handler
     * @param ex
     * @throws Exception
     */
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("响应视图之后...");
    }
}