XML聲明，定義XML的版本、編碼格式。還有最重要的schema的來源
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" version="2.4">
.......
</web-app>
<description>
當servlet的URL定義為其他文件類型的擴展名,該文件類型將不能訪問,而訪問了servlet
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" version="2.4">
<display-name>myweb</display-name><!--站點名稱-->
<description>這里是站點描述</description>
<icon>
<small-icon>/images/small.gif</small-icon><!--小圖標的路徑16*16,必須為gif jpge格式-->
<large-icon>/images/large.gif</large-icon><!--大圖標的路徑32*32,必須為gif jpge格式-->
</icon>
<!--如果存在<distributable/>則代表該站點能在多個JSP Container之間分散執(zhí)行(分布式)-->
<distributable/>
<context-param><!--環(huán)境參數(shù),設置常量,取得常量 this.getInitParameter("context");-->
<param-name>context</param-name>
<param-value>10000</param-value>
</context-param>
<filter><!--聲明filter-->
<filter-name>filterName</filter-name>
<filter-class>filter.filterName</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
</filter>
<filter-mapping><!--定義filter所對應的URL-->
<filter-name>filterName</filter-name>
<url-pattern>/filterName</url-pattern>
<dispatcher>REQUEST|INCLUDE|FORWARD|ERROR</dispatcher><!--filter對應的請求方式,有4種方式,默認REQUEST-->
</filter-mapping>
<listener><!--設定Listener接口-->
<listener-class>listener.ListenerClassName</listener-class>
</listener>
<servlet><!--聲明servlet的數(shù)據(jù)-->
<servlet-name>servletName</servlet-name>
<servlet-class>servlet.servletName</servlet-class>
<init-param><!--初始化參數(shù),可以在init()中使用ServletConfig().getInitParamenter("name")取得-->
<param-name>name</param-name>
<param-value>123</param-value>
</init-param>
<load-on-startup>n</load-on-startup><!--站點啟動時,此servlet會被自動加載執(zhí)行,1表示最早,2,3...-->
</servlet>
<servlet-mapping><!--定義servlet所對應的URL-->
<servlet-name>name</servlet-name>
<url-pattern>/name</url-pattern>
</servlet-mapping>
<session-config><!--設置session超時時間（20分鐘）默認按服務器配置-->
<session-timeout>20</session-timeout>
</session-config>
<mime-mapping><!--定義某個擴展名和某個MIME Type做映射-->
<extension>doc</extension>
<mime-type>application/vnd.ms-word</mime-type>
</mime-mapping>
<welcome-file-list><!--設置首頁列表-->
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<error-page><!--將錯誤代碼對應到WEB站點的資源路徑-->
<error-code>錯誤代碼</error-code>Exception
<location>/路徑/</location>
</error-page>
<error-page><!--將異常的種類對應到WEB站點的資源路徑-->
<exception-type>Exception</exception-type>
<location>/路徑/</location>
</error-page>
<jsp-config><!--JSP的相關配置-->
<taglib><!--JSP所用到的Tag Library-->
<taglib-uri>URI</taglib-uri>
<taglib-location>/WEB-INF/lib/xxx.tld</taglib-location>
</taglib>
<jsp-property-group>
<description>此設定的說明</description>
<display-name>Name</display-name>
<url-pattern>URL</url-pattern><!--此設定影響的范圍-->
<el-ignored>true|false</el-ignored><!--true表示不支持EL語法-->
<scripting-invalid>encoding</scripting-invalid><!--jsp的編碼-->
<include-coda>...jspf</include-coda><!--JSP的結尾,擴展名.jspf-->
</jsp-property-group>
</jsp-config>
<resource-ref><!--利用JNDI取得站點可利用的資源-->
<description>資源說明</description>
<res-ref-name>資源名稱</res-ref-name>
<res-type>資源種類</res-type>
<res-auth>Application|Container</res-auth><!--資源經(jīng)由什么許可-->
<res-sharing-scope>Shareable|Unshareable</res-sharing-scope><!--資源是否可以共享,默認為Shareable-->
</resource-ref>
</web-app>
