到http://apache.towardex.com/jakarta/taglibs/standard/下载了最新的jstl，然后把standard.jar和jstl.jar文件拷贝到\WEB-INF\lib\下，\tld\下的8个tld类型文件拷到"\WEB-INF\"下。
接下来配置web.xml文件，这里我就有些糊涂了。
下面这个是《jsp设计》的web.xml
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE web-app
PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com//dtd/web-app_2_3.dtd">
<web-app>
<!-- Used by the JSTL I18N actions -->
<context-param>
<param-name>
javax.servlet.jsp.jstl.fmt.fallbackLocale
</param-name>
<param-value>
en
</param-value>
</context-param>
<!-- Used by the JSTL database actions -->
<context-param>
<param-name>
javax.servlet.jsp.jstl.sql.dataSource
</param-name>
<param-value>
jdbc:mysql:///test,org.gjt.mm.mysql.Driver
</param-value>
</context-param>
<!-- Used by the ResourceManagerListener in Chapter 18 -->
<context-param>
<param-name>driverClass</param-name>
<param-value>
org.gjt.mm.mysql.Driver
</param-value>
</context-param>
<context-param>
<param-name>jdbcURL</param-name>
<param-value>
jdbc:mysql:///test
</param-value>
</context-param>
<!-- Filter and listener configurations for Chapter 18 -->
<filter>
<filter-name>accessControl</filter-name>
<filter-class>
com.ora.jsp.servlets.AccessControlFilter
</filter-class>
<init-param>
<param-name>loginPage</param-name>
<param-value>/ch18/login.jsp</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>accessControl</filter-name>
<url-pattern>/ch18/protected/*</url-pattern>
</filter-mapping>
<listener>
<listener-class>
com.ora.jsp.servlets.ResourceManagerListener
</listener-class>
</listener>
<listener>
<listener-class>
com.ora.jsp.servlets.SessionCounterListener
</listener-class>
</listener>
<!-- Servlet for showing JSP source. NOTE! Remove this in production -->
<servlet>
<servlet-name>jspSource</servlet-name>
<servlet-class>JSPSourceServlet</servlet-class>
</servlet>
<!--
Servlet for handling both servlet and JSP errors, see Chapter 18
-->
<servlet>
<servlet-name>errorDispatcher</servlet-name>
<servlet-class>com.ora.jsp.servlets.ErrorDispatcherServlet</servlet-class>
<init-param>
<param-name>errorPage</param-name>
<param-value>/ch9/errorpage.jsp?debug=resp</param-value>
</init-param>
</servlet>
<!-- Struts Controller servlet, see Chapter 18 -->
<servlet>
<servlet-name>action</servlet-name>
<servlet-class>org.apache.struts.action.ActionServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>jspSource</servlet-name>
<url-pattern>/jspSource/*</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>errorDispatcher</servlet-name>
<url-pattern>/errorDispatcher</url-pattern>
</servlet-mapping>
<!-- Struts Controller servlet mapping, see Chapter 18 -->
<servlet-mapping>
<servlet-name>action</servlet-name>
<url-pattern>*.do</url-pattern>
</servlet-mapping>
<!-- The Welcome File List -->
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<!--
Uncomment if you want all exceptions and 500 status codes to
be handled by the customized error page.
<error-page>
<exception-type>java.lang.Throwable</exception-type>
<location>/errorDispatcher</location>
</error-page>
<error-page>
<error-code>500</error-code>
<location>/errorDispatcher</location>
</error-page>
-->
<!--
This resource reference is only used to test the JNDI config described
in Chapter 23. None of the examples use it.
-->
<resource-ref>
<description>
JNDI DataSource for example database
</description>
<res-ref-name>jdbc/Example</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
<res-sharing-scope>Sharable</res-sharing-scope>
</resource-ref>
<!-- Security constraints for examples in Chapter 12 -->
<security-constraint>
<web-resource-collection>
<web-resource-name>admin</web-resource-name>
<url-pattern>/ch12/admin/*</url-pattern>
<url-pattern>/ch12/search/delete.jsp</url-pattern>
</web-resource-collection>
<auth-constraint>
<role-name>admin</role-name>
</auth-constraint>
</security-constraint>
<security-constraint>
<web-resource-collection>
<web-resource-name>search</web-resource-name>
<url-pattern>/ch12/search/*</url-pattern>
</web-resource-collection>
<auth-constraint>
<role-name>admin</role-name>
<role-name>user</role-name>
</auth-constraint>
</security-constraint>
<login-config>
<auth-method>BASIC</auth-method>
<realm-name>ORA Examples</realm-name>
</login-config>
<security-role>
<role-name>admin</role-name>
</security-role>
<security-role>
<role-name>user</role-name>
</security-role>
</web-app>
另外在网上找到了一个家伙写的web.xml
<?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">
<taglib>
<taglib-uri>http://java.sun.com/jstl/fmt</taglib-uri>
<taglib-location>/WEB-INF/fmt.tld</taglib-location>
</taglib>
<taglib>
<taglib-uri>http://java.sun.com/jstl/fmt-rt</taglib-uri>
<taglib-location>/WEB-INF/fmt-rt.tld</taglib-location>
</taglib>
<taglib>
<taglib-uri>http://java.sun.com/jstl/core</taglib-uri>
<taglib-location>/WEB-INF/c.tld</taglib-location>
</taglib>
<taglib>
<taglib-uri>http://java.sun.com/jstl/core-rt</taglib-uri>
<taglib-location>/WEB-INF/c-rt.tld</taglib-location>
</taglib>
<taglib>
<taglib-uri>http://java.sun.com/jstl/sql</taglib-uri>
<taglib-location>/WEB-INF/sql.tld</taglib-location>
</taglib>
<taglib>
<taglib-uri>http://java.sun.com/jstl/sql-rt</taglib-uri>
<taglib-location>/WEB-INF/sql-rt.tld</taglib-location>
</taglib>
<taglib>
<taglib-uri>http://java.sun.com/jstl/x</taglib-uri>
<taglib-location>/WEB-INF/x.tld</taglib-location>
</taglib>
<taglib>
<taglib-uri>http://java.sun.com/jstl/x-rt</taglib-uri>
<taglib-location>/WEB-INF/x-rt.tld</taglib-location>
</taglib>
<session-config>
<session-timeout>
30
</session-timeout>
</session-config>
<welcome-file-list>
<welcome-file>
index.jsp
</welcome-file>
</welcome-file-list>
</web-app>
两个都可以使用，我有些糊涂了，究竟在web.xml 中到底是要申明些什么，起到什么作用呢？
知道的请告诉我，谢谢！