java web开发入门十二（idea创建maven SSM项目需要解决的问题）基于intellig idea（2019-11-09 11:23）

    <!-- 注册string和json解析适配器 -->
    <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
        <property name="messageConverters">
            <list>

                <bean class="org.springframework.http.converter.StringHttpMessageConverter"/>
                <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"/>
            </list>
        </property>
    </bean>

 <!-- 注册springmvc核心控制器-->
    <servlet>
        <!--servlet-name的值对应一个文件：/WEB-INF/DispatcherServlet-servlet.xml   -->
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <!-- 指定application.xml文件 -->
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springmvc.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <!--  <url-pattern>*.action</url-pattern>-->
        <!--默认匹配所有请求-->
        <!--Spring MVC将捕获Web容器所有的请求，包括静态资源的请求，Spring MVC会将它们当成一个普通请求处理-->
        <url-pattern>/</url-pattern>
    </servlet-mapping>

<!-- 配置SpringMVC -->
    <!-- 1.开启SpringMVC注解模式 -->
    <!-- 简化配置：
        (1)自动注册DefaultAnootationHandlerMapping,AnotationMethodHandlerAdapter
        (2)提供一些列：数据绑定，数字和日期的format @NumberFormat, @DateTimeFormat, xml,json默认读写支持
    -->
    <mvc:annotation-driven/>

    <!--
    静态资源交给servlet处理，
    在springMVC-servlet.xml中配置<mvc:default-servlet-handler />后，
    会在Spring MVC上下文中定义一个org.springframework.web.servlet.resource.DefaultServletHttpRequestHandler，
    它会像一个检查员，对进入DispatcherServlet的URL进行筛查，
    如果发现是静态资源的请求，就将该请求转由Web应用服务器默认的Servlet处理，
    如果不是静态资源的请求，才由DispatcherServlet继续处理。
    -->
    <mvc:default-servlet-handler/>

package com.eggtwo.euq.interceptor;

import com.eggtwo.euq.dto.CurrentSysUser;
import com.eggtwo.euq.utils.CacheUtil;
import com.eggtwo.euq.utils.ConfigUtil;
import com.eggtwo.euq.utils.CookieUtil;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

public class LoginInterceptor implements HandlerInterceptor {
    private boolean isAjaxRequest(HttpServletRequest request) {
        if (request.getHeader("x-requested-with") != null && request.getHeader("x-requested-with").equalsIgnoreCase("XMLHttpRequest")) {
            //如果是ajax请求响应头会有，x-requested-with
            System.out.print("发生ajax请求...");
            return true;

        }
        return false;
    }


    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {

        String requestUri = request.getRequestURI(); //请求完整路径，可用于登陆后跳转
        String contextPath = request.getContextPath();  //项目下完整路径
        String url = requestUri.substring(contextPath.length()); //请求页面
        System.out.print("发生拦截...");
        System.out.println("来自：" + requestUri + "的请求");

        //拿到cookie
        //也就是获取session里的登录状态值
        String cookieKey = ConfigUtil.getBossCookieKey();
        String cookieValue = CookieUtil.getByName(request, cookieKey);
        CurrentSysUser currentSysUser =null;
        String errorMsg=null;
        if (cookieValue == null) {
            errorMsg="no login,please login";
        }else{
            currentSysUser = CacheUtil.getT(cookieValue);
            if (currentSysUser == null) {
                errorMsg="no login,please login";
            }
        }
        if (errorMsg!=null){
            if (isAjaxRequest(request)) {
                response.setContentType("application/json; charset=utf-8");
                PrintWriter writer = response.getWriter();
                writer.print("{type:0,msg:‘"+errorMsg+"‘}");
                writer.close();
                response.flushBuffer();
            } else {
                String basePath= request.getContextPath();
                response.sendRedirect(basePath+"/account/login?error="+errorMsg);
            }
            return false;//返回false不走下面的方法
        }
        //更新缓存过期时间
        CacheUtil.remove(cookieValue);
        CacheUtil.set(cookieValue, currentSysUser, ConfigUtil.getBossCookieTimeoutSecond());
        //更新cookie过期时间--覆盖原有的cookie
        CookieUtil.deleteCookie(response, cookieKey);
        //写入cookie
        CookieUtil.addCookie(response, cookieKey, cookieValue, ConfigUtil.getBossCookieTimeoutSecond());



        return true;
    }

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

    }

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

    }
}

 <!--配置拦截器, 多个拦截器,顺序执行 -->
    <mvc:interceptors>
        <mvc:interceptor>
            <!-- 先匹配所有路径，然后排除不需要检查的路径 -->
            <mvc:mapping path="/**"/>


            <!--不拦截的action-->
            <mvc:exclude-mapping path="/account/login"/>
            <mvc:exclude-mapping path="/account/logout"/>

            <!-- 网站的登录路径是 "http://localhost:8080/cultivate-job/"
                路径path="/"表示的路径就是网站入口路径,
                也就是说拦截器只方向两种请求:
                1. 错误页面,直接访问jsp页面,这些页面不在WEB-INF目录下,可以直接访问
                2. 网站入口请求,检查到没有登录,会重定向到网站入口路径,再被定向到登录页面
            -->
            <mvc:exclude-mapping path="/"/>
            <!-- 以下是静态资源 -->
            <mvc:exclude-mapping path="/content/**" />
            <mvc:exclude-mapping path="/images/**" />
            <mvc:exclude-mapping path="/js/**" />
            <mvc:exclude-mapping path="/css/**" />
            <mvc:exclude-mapping path="/upload/**" />
            <mvc:exclude-mapping path="/download/**" />

            <!-- 自定义拦截器路径 -->
            <bean class="com.eggtwo.euq.interceptor.LoginInterceptor"></bean>
        </mvc:interceptor>
        <!-- 当设置多个拦截器时，先按顺序调用preHandle方法，然后逆序调用每个拦截器的postHandle和afterCompletion方法 -->
    </mvc:interceptors>