Spring 配置DispatcherServlet
本文描述了web.xml最基本配置方式。
Spring MVC的核心是DispatcherServlet,作为Spring MVC的前端控制器;
和任何Servlet一样,我们需要在web.xml文件中配置DispatcherServlet;
下面的描述以这个web.xml为例:
<?xml version="1.0" encoding="UTF-8"?> <web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> <!-- The definition of the Root Spring Container shared by all Servlets and Filters --> <context-param> <param-name>contextConfigLocation</param-name> <param-value> /WEB-INF/iSystem-beans.xml, </param-value> </context-param> <!-- Creates the Spring Container shared by all Servlets and Filters --> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> <!-- Processes application requests --> <servlet> <servlet-name>iSystem</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <init-param> <param-name>contextConfigLocation</param-name> <param-value>/WEB-INF/iSystem-servlet.xml</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>iSystem</servlet-name> <url-pattern>/</url-pattern> <url-pattern>*.htm</url-pattern> </servlet-mapping> </web-app>
在其中的<servlet>标签下,定义了DispatcherServlet。
重要:在DispatcherServlet载入后,它将从XML文件中载入Spring的应用上下文,这个XML文件的名字取决于Servlet的名字,或者由init-param来指定。
如果我们不设置init-param,形如:
<servlet> <servlet-name>iSystem</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <load-on-startup>1</load-on-startup> </servlet>
这时,DispatcherServlet载入后将默认去加载 /WEB-INF/iSystem-servlet.xml文件,iSystem就是上面定义的servlet-name。
如果没有这个文件,将会报错:
java.io.FileNotFoundException: Could not open ServletContext resource [/WEB-INF/iSystem-servlet.xml]
因此我们如果省略init-param的话,需要按下图放置该xml:
附上模板工程自带的servlet.xml文件内容:
<?xml version="1.0" encoding="UTF-8"?> <beans:beans xmlns="http://www.springframework.org/schema/mvc" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:beans="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> <!-- DispatcherServlet Context: defines this servlet‘s request-processing infrastructure --> <!-- Enables the Spring MVC @Controller programming model --> <annotation-driven /> <!-- Handles HTTP GET requests for /resources/** by efficiently serving up static resources in the ${webappRoot}/resources directory --> <resources mapping="/resources/**" location="/resources/" /> <!-- Resolves views selected for rendering by @Controllers to .jsp resources in the /WEB-INF/views directory --> <beans:bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <beans:property name="prefix" value="/WEB-INF/views/" /> <beans:property name="suffix" value=".jsp" /> </beans:bean> <context:component-scan base-package="com.codeevoship.app" /> </beans:beans>
接下来再为DispatcherServlet指定需要处理的URL:
<servlet-mapping> <servlet-name>iSystem</servlet-name> <url-pattern>/</url-pattern> <url-pattern>*.htm</url-pattern> </servlet-mapping>
当然这里还可以加上*.png、*.gif等等等等……
到这里DispatcherServlet的配置就完成了,这里再说说其他内容。
虽然我们已经加载了iSystem-servlet.xml,虽然可以把全项目所有的bean全都定义在这一个xml中……
推荐分层、分模块分别定义,比如iSystem-security.xml/iSystem-data.xml/iSystem-service.xml……
这就用到了上下文载入器,最常用的ContextLoaderListener:
<!-- Creates the Spring Container shared by all Servlets and Filters --> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener>
这个载入器可以载入除DispatcherServlet载入的配置文件之外的其他上下文配置文件,通过下述方式:
<context-param> <param-name>contextConfigLocation</param-name> <param-value> /WEB-INF/iSystem-security.xml, /WEB-INF/iSystem-data.xml, </param-value> </context-param>
param-value中就是需要加载的文件,以逗号分隔。
以上就是web.xml的最基本配置。
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