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>