有些时候，<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>会报错，错误提示为：
Can not find the tag library descriptor for "http://java.sun.com/jsp/jstl/core"
主要原因是缺少
jstl.jar
standard.jar
两个Jar包
如果还不行，请调整jstl.jar 版本，这个主要根据web的version的版本有关。增加如下
<jsp-config>
<taglib>
<taglib-uri>http://java.sun.com/jstl/fmt</taglib-uri>
<taglib-location>/WEB-INF/tlds/fmt.tld</taglib-location>
</taglib>
<taglib>
<taglib-uri>http://java.sun.com/jstl/fmt-rt</taglib-uri>
<taglib-location>/WEB-INF/tlds/fmt-rt.tld</taglib-location>
</taglib>
<taglib>
<taglib-uri>http://java.sun.com/jstl/core</taglib-uri>
<taglib-location>/WEB-INF/tlds/c.tld</taglib-location>
</taglib>
</jsp-config>
<taglib>
<taglib-uri>http://java.sun.com/jstl/fmt</taglib-uri>
<taglib-location>/WEB-INF/tlds/fmt.tld</taglib-location>
</taglib>
<taglib>
<taglib-uri>http://java.sun.com/jstl/fmt-rt</taglib-uri>
<taglib-location>/WEB-INF/tlds/fmt-rt.tld</taglib-location>
</taglib>
<taglib>
<taglib-uri>http://java.sun.com/jstl/core</taglib-uri>
<taglib-location>/WEB-INF/tlds/c.tld</taglib-location>
</taglib>
</jsp-config>