web.xml里listener、filter和servlet加载顺序和详解（二）
相应元素配置
1、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>
2、Web 应用名称：提供GUI工具可能会用来标记这个特定的Web应用的一个名称
<display-name>Tomcat Example</display-name>
3、Web 应用描述： 给出于此相关的说明性文本
<disciption>Tomcat Example servlets and JSP pages.</disciption>
4、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>
在servlet里面可以通过getServletContext().getInitParameter("context/param")得到
5、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>
6、监听器配置
<listener>
????? <listerner-class>listener.SessionListener</listener-class>
</listener>
7、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>
?? 元素说明
???? <servlet></servlet> 用来声明一个servlet的数据，主要有以下子元素：
???? <servlet-name></servlet-name> 指定servlet的名称
???? <servlet-class></servlet-class> 指定servlet的类名称
???? <jsp-file></jsp-file> 指定web站台中的某个JSP网页的完整路径
???? <init-param></init-param> 用来定义参数，可有多个init-param。在servlet类中通过getInitParamenter(String name)方法访问初始化参数
???? <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
???? <servlet-mapping></servlet-mapping> 用来定义servlet所对应的URL，包含两个子元素
?????? <servlet-name></servlet-name> 指定servlet的名称
?????? <url-pattern></url-pattern> 指定servlet所对应的URL
8、会话超时配置（单位为分钟）
?? <session-config>
????? <session-timeout>120</session-timeout>
?? </session-config>
9、MIME类型配置
?? <mime-mapping>
????? <extension>htm</extension>
????? <mime-type>text/html</mime-type>
?? </mime-mapping>
10、指定欢迎文件页配置
?? <welcome-file-list>
????? <welcome-file>index.jsp</welcome-file>
????? <welcome-file>index.html</welcome-file>
????? <welcome-file>index.htm</welcome-file>
?? </welcome-file-list>
11、配置错误页面
一、 通过错误码来配置error-page
?? <error-page>
????? <error-code>404</error-code>
????? <location>/NotFound.jsp</location>
?? </error-page>
上面配置了当系统发生404错误时，跳转到错误处理页面NotFound.jsp。
二、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>
上面配置了当系统发生java.lang.NullException（即空指针异常）时，跳转到错误处理页面error.jsp
12、TLD配置
?? <taglib>
?????? <taglib-uri>http://jakarta.apache.org/tomcat/debug-taglib</taglib-uri>
?????? <taglib-location>/WEB-INF/jsp/debug-taglib.tld</taglib-location>
?? </taglib>
?? 如果MyEclipse一直在报错,应该把<taglib> 放到 <jsp-config>中
?? <jsp-config>
????? <taglib>
????????? <taglib-uri>http://jakarta.apache.org/tomcat/debug-taglib</taglib-uri>
????????? <taglib-location>/WEB-INF/pager-taglib.tld</taglib-location>
????? </taglib>
?? </jsp-config>
13、资源管理对象配置
?? <resource-env-ref>
?????? <resource-env-ref-name>jms/StockQueue</resource-env-ref-name>
?? </resource-env-ref>
14、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>
15、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>
