web.xml可以配置哪些内容

web.xm用于配置Web应用的相关信息
如: 监听器（listener）[@WebListener] 、过滤器（filter）[@WebFilter]、Servlet [@WebServlet]、相关参数、会话超时时间、安全验证方式、错误页面等

配置Spring上下文加载监听器加载Spring配置文件并创建IoC容器

<context-param>
	<param-name>contextConfigLocation</param-name>
	<param-value>classpath:applicationContext.xml</param-value>
</context-param>

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

配置Spring的OpenSessionInView过滤器来解决延迟加载和Hibernate会话关闭的矛盾

<filter>
	<filter-name>openSessonInView</filter-name>
	<filter-class>
		org.springframework.orm.hibernate3.support.OpenSessionInViewFilter
	</filter-class>
</filter>

<filter-mapping>
	<filter-name>openSessionInView</filter-name>
	<url-pattern>/*</url-pattern>
</filter-mapping>

配置会话超时时间为10分钟

<session-config>
	<session-timeout>10</session-timeout>
</session-config>

配置404和Exception的错误页面

<error-page>
	<error-code>404</error-code>
	<location>/error.jsp</location>
</error-page>
<error-page>
	<exception-type>java.lang.Exception</exception-type>
	<location>/error.jsp</location>
</error-page>

配置安全认证方式

<security-constraint>
    <web-resource-collection>
        <web-resource-name>ProtectedArea</web-resource-name>
        <url-pattern>/admin/*</url-pattern>
        <http-method>GET</http-method>
        <http-method>POST</http-method>
    </web-resource-collection>
    <auth-constraint>
        <role-name>admin</role-name>
    </auth-constraint>
</security-constraint>

<login-config>
    <auth-method>BASIC</auth-method>
</login-config>

<security-role>
    <role-name>admin</role-name>
</security-role>