servlet,web.xml文件配置祥解

web-app:必备，出现在首尾
上下文参数：声明应用范围内的初始化参数。
<context-param>
<param-name>ContextParameter</para-name>
<param-value>test</param-value>
<description>It is a test parameter.</description>
</context-param>
<display-name></display-name>定义了WEB应用的名字
<description></description> 声明WEB应用的描述信息
<welcome-file-list></welcome-file-list> 指示服务器在收到引用一个目录名而不是文件名的URL时，使用哪个文件
错误页：使用错误信息
<error-page>
<error-code>500</error-code>
<location>/error.jsp</location>
</error-page>
通过异常的类型配置error-page
<error-page>
<exception-type>java.lang.NullException</exception-type>
<location>/error.jsp</location>
</error-page>
Web应用图标：指出IDE和GUI工具用来表示Web应用的大图标和小图标
<icon>
<small-icon>/images/app_small.gif</small-icon>
<large-icon>/images/app_large.gif</large-icon>
</icon>
过滤器配置：将一个名字与一个实现javaxs.servlet.Filter接口的类相关联。
<filter>
<filter-name>setCharacterEncoding</filter-name>
<filter-class>com.myTest.setCharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>GB2312</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>setCharacterEncoding</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
监听器配置
<listener>
<listerner-class>listener.SessionListener</listener-class>
</listener>
Servlet配置
基本配置
<servlet>
<servlet-name>snoop</servlet-name>
<servlet-class>SnoopServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>snoop</servlet-name>
<url-pattern>/snoop</url-pattern>
</servlet-mapping>
高级配置
<servlet>
<servlet-name>snoop</servlet-name>
<servlet-class>SnoopServlet</servlet-class>
<init-param>
<param-name>foo</param-name>
<param-value>bar</param-value>
</init-param>
<run-as>
<description>Security role for anonymous access</description>
<role-name>tomcat</role-name>
</run-as>
</servlet>
<servlet-mapping>
<servlet-name>snoop</servlet-name>
<url-pattern>/snoop</url-pattern>
</servlet-mapping>
<load-on-startup></load-on-startup>指定当Web应用启动时，装载Servlet的次序。 当值为正数或零时：Servlet容器先加载数值小的servlet，再依次加载其他数值大的servlet. 当值为负或未定义：Servlet容器将在Web客户首次访问这个servlet时加载它
会话超时配置（单位为分钟）<session-config>
<session-timeout>120</session-timeout>
</session-config>
MIME类型配置
<mime-mapping>
<extension>htm</extension>
<mime-type>text/html</mime-type>
</mime-mapping>
资源管理对象配置
<resource-env-ref>
<resource-env-ref-name>jms/StockQueue</resource-env-ref-name>
</resource-env-ref>
资源工厂配置
<resource-ref>
<res-ref-name>mail/Session</res-ref-name>
<res-type>javax.mail.Session</res-type>
<res-auth>Container</res-auth>
</resource-ref>
配置数据库连接池就可在此配置：
<resource-ref>
<description>JNDI JDBC DataSource of shop</description>
<res-ref-name>jdbc/sample_db</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
安全限制配置
<security-constraint>
<display-name>Example Security Constraint</display-name>
<web-resource-collection>
<web-resource-name>Protected Area</web-resource-name>
<url-pattern>/jsp/security/protected/*</url-pattern>
<http-method>DELETE</http-method>
<http-method>GET</http-method>
<http-method>POST</http-method>
<http-method>PUT</http-method>
</web-resource-collection>
<auth-constraint>
<role-name>tomcat</role-name>
<role-name>role1</role-name>
</auth-constraint>
</security-constraint>
16、登陆验证配置
<login-config>
<auth-method>FORM</auth-method>
<realm-name>Example-Based Authentiation Area</realm-name>
<form-login-config>
<form-login-page>/jsp/security/protected/login.jsp</form-login-page>
<form-error-page>/jsp/security/protected/error.jsp</form-error-page>
</form-login-config>
</login-config>
17、安全角色：security-role元素给出安全角色的一个列表，这些角色将出现在servlet元素内的security-role-ref元素的role-name子元素中。
分别地声明角色可使高级IDE处理安全信息更为容易。
<security-role>
<role-name>tomcat</role-name>
</security-role>
18、Web环境参数：env-entry元素声明Web应用的环境项
<env-entry>
<env-entry-name>minExemptions</env-entry-name>
<env-entry-value>1</env-entry-value>
<env-entry-type>java.lang.Integer</env-entry-type>
</env-entry>
19、EJB 声明
<ejb-ref>
<description>Example EJB reference</decription>
<ejb-ref-name>ejb/Account</ejb-ref-name>
<ejb-ref-type>Entity</ejb-ref-type>
<home>com.mycompany.mypackage.AccountHome</home>
<remote>com.mycompany.mypackage.Account</remote>
</ejb-ref>
20、本地EJB声明
<ejb-local-ref>
<description>Example Loacal EJB reference</decription>
<ejb-ref-name>ejb/ProcessOrder</ejb-ref-name>
<ejb-ref-type>Session</ejb-ref-type>
<local-home>com.mycompany.mypackage.ProcessOrderHome</local-home>
<local>com.mycompany.mypackage.ProcessOrder</local>
</ejb-local-ref>
21、配置DWR
<servlet>
<servlet-name>dwr-invoker</servlet-name>
<servlet-class>uk.ltd.getahead.dwr.DWRServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>dwr-invoker</servlet-name>
<url-pattern>/dwr/*</url-pattern>
</servlet-mapping>
22、配置Struts
<display-name>Struts Blank Application</display-name>
<servlet>
<servlet-name>action</servlet-name>
<servlet-class>
org.apache.struts.action.ActionServlet
</servlet-class>
<init-param>
<param-name>detail</param-name>
<param-value>2</param-value>
</init-param>
<init-param>
<param-name>debug</param-name>
<param-value>2</param-value>
</init-param>
<init-param>
<param-name>config</param-name>
<param-value>/WEB-INF/struts-config.xml</param-value>
</init-param>
<init-param>
<param-name>application</param-name>
<param-value>ApplicationResources</param-value>
</init-param>
<load-on-startup>2</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>action</servlet-name>
<url-pattern>*.do</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>

<!-- Struts Tag Library Descriptors -->
<taglib>
<taglib-uri>struts-bean</taglib-uri>
<taglib-location>/WEB-INF/tld/struts-bean.tld</taglib-location>
</taglib>
<taglib>
<taglib-uri>struts-html</taglib-uri>
<taglib-location>/WEB-INF/tld/struts-html.tld</taglib-location>
</taglib>
<taglib>
<taglib-uri>struts-nested</taglib-uri>
<taglib-location>/WEB-INF/tld/struts-nested.tld</taglib-location>
</taglib>
<taglib>
<taglib-uri>struts-logic</taglib-uri>
<taglib-location>/WEB-INF/tld/struts-logic.tld</taglib-location>
</taglib>
<taglib>
<taglib-uri>struts-tiles</taglib-uri>
<taglib-location>/WEB-INF/tld/struts-tiles.tld</taglib-location>
</taglib>
23、配置Spring（基本上都是在Struts中配置的）

<!-- 指定spring配置文件位置 -->
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>
<!--加载多个spring配置文件 -->
/WEB-INF/applicationContext.xml, /WEB-INF/action-servlet.xml
</param-value>
</context-param>

<!-- 定义SPRING监听器，加载spring -->

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

<listener>
<listener-class>
org.springframework.web.context.request.RequestContextListener
</listener-class>
</listener>