web工程中web.xml元素加载顺序以及配置实例

web工程中web.xml元素加载顺序以及配置实例

简介

web.xml是web工程的配置文件，容器加载web工程时，会首先从WEB-INF中查询web.xml，并加载其中的配置信息，可以将web.xml认为是web工程的入口。

web.xml中包含有welcome欢迎页面、servlet、servlet-mapping、filter、listener和启动加载级别等。

web.xml加载顺序

容器读取工程的配置文件web.xml，读取<listener>和<context-param>两个节点。

容器创建ServletContext，所有的web项目都将共享该ServletContext。

容器将<context-param>转换为键值对，并交给ServletContext。

容器创建<listener>中的类的实例，创建监听器

web.xml内容详解

<?xml version="1.0" encoding="UTF-8"?>

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

xmlns:web="http://java.sun.com/xml/ns/javaee" xmlns="http://java.sun.com/xml/ns/javaee"

xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" 
id="WebApp_ID" version="3.0">

<display-name>console</display-name>

<!--servletContext加载的属性信息 -->

<context-param>

<param-name>contextConfigLocation</param-name>

<param-value>classpath:spring.xml,classpath:spring-mybatis.xml,classpath:spring-shiro.xml</param-value>

</context-param>

<!-- 定义过滤器的名称，以及其初始化参数-->

<filter>

<filter-name>shiroFilter</filter-name>

<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>

<init-param>

<param-name>targetFilterLifecycle</param-name>

<param-value>true</param-value>

</init-param>

</filter>

<!-- 定义url被哪个filter过滤，下面的配置表示所有的请求都必须经过shiroFilter  -->

<filter-mapping>

<filter-name>shiroFilter</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

<filter>

<filter-name>ResponseCrossFilter</filter-name>

<filter-class>com.emcc.changedig.filter.ResponseCrossFilter</filter-class>

</filter>

<filter-mapping>

<filter-name>ResponseCrossFilter</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

<!--  定义监听器，控制容器在启动和停止时的行为 -->

<listener>

<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>

</listener>

<filter>

<filter-name>encodingFilter</filter-name>

<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>

<init-param>

<description>字符集编码</description>

<param-name>encoding</param-name>

<param-value>UTF-8</param-value>

</init-param>

</filter>

<filter-mapping>

<filter-name>encodingFilter</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

<!--  清理监听器，当应用停止时，使用该listener释放资源 -->

<listener>

<listener-class>org.springframework.web.util.IntrospectorCleanupListener</listener-class>

</listener>

<! – 定义servlet，初始化参数以及启动顺序 -->

<servlet>

<description>spring mvc servlet</description>

<servlet-name>springMvc</servlet-name>

<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>

<init-param>

<description>spring mvc 配置文件</description>

<param-name>contextConfigLocation</param-name>

<param-value>classpath:spring-mvc.xml</param-value>

</init-param>

<load-on-startup>1</load-on-startup>

</servlet>

<servlet>

<servlet-name>DruidStatView</servlet-name>

<servlet-class>com.alibaba.druid.support.http.StatViewServlet</servlet-class>

<init-param>

<!-- 允许清空统计数据 -->

<param-name>resetEnable</param-name>

<param-value>true</param-value>

</init-param>

<init-param>

<!-- 用户名 -->

<param-name>loginUsername</param-name>

<param-value>druid</param-value>

</init-param>

<init-param>

<!-- 密码 -->

<param-name>loginPassword</param-name>

<param-value>druid</param-value>

</init-param>

</servlet>

<!-- 定义servlet 映射规则 -->

<servlet-mapping>

<servlet-name>DruidStatView</servlet-name>

<url-pattern>/druid/*</url-pattern>

</servlet-mapping>

<servlet-mapping>

<servlet-name>springMvc</servlet-name>

<url-pattern>/</url-pattern>

</servlet-mapping>

<session-config>

<!-- 时间单位是分钟 -->

<session-timeout>360</session-timeout>

</session-config>

<!-- default表示，对客户端请求的静态资源，交由默认的servlet来处理 -->

<servlet-mapping>

<servlet-name>default</servlet-name>

<url-pattern>*.css</url-pattern>

</servlet-mapping>

<servlet-mapping>

<servlet-name>default</servlet-name>

<url-pattern>*.js</url-pattern>

</servlet-mapping>

<servlet-mapping>

<servlet-name>default</servlet-name>

<url-pattern>*.ico</url-pattern>

</servlet-mapping>

<servlet-mapping>

<servlet-name>default</servlet-name>

<url-pattern>*.gif</url-pattern>

</servlet-mapping>

<servlet-mapping>

<servlet-name>default</servlet-name>

<url-pattern>*.jpg</url-pattern>

</servlet-mapping>

<servlet-mapping>

<servlet-name>default</servlet-name>

<url-pattern>*.png</url-pattern>

</servlet-mapping>

<servlet-mapping>

<servlet-name>default</servlet-name>

<url-pattern>*.bmp</url-pattern>

</servlet-mapping>

<servlet-mapping>

<servlet-name>default</servlet-name>

<url-pattern>*.jpeg</url-pattern>

</servlet-mapping>

<servlet-mapping>

<servlet-name>default</servlet-name>

<url-pattern>*.swf</url-pattern>

</servlet-mapping>

<servlet-mapping>

<servlet-name>default</servlet-name>

<url-pattern>*.flv</url-pattern>

</servlet-mapping>

<servlet-mapping>

<servlet-name>default</servlet-name>

<url-pattern>*.xml</url-pattern>

</servlet-mapping>

<servlet-mapping>

<servlet-name>default</servlet-name>

<url-pattern>*.txt</url-pattern>

</servlet-mappi
4000
ng>

<servlet-mapping>

<servlet-name>default</servlet-name>

<url-pattern>*.htm</url-pattern>

</servlet-mapping>

<servlet-mapping>

<servlet-name>default</servlet-name>

<url-pattern>*.html</url-pattern>

</servlet-mapping>

<!--  定义错误返回页面  -->

<error-page>

<error-code>404</error-code>

<location>/web/error/404.html</location>

</error-page>

</web-app>