【Tomcat版本】7.0.42
【问题描述】Tomcat启动后，访问动态页面后提示“At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned but no TLDs were found in them. Skipping unneeded JARs during scanning can improve startup time and JSP compilation time”
【问题原因猜测】Tomcat7/Servlet3.0 新增特性“可插性支持”实现的原理应该是自动扫描jar，当jar中并不包含相关组件时会打印该信息
【问题处理】从提示信息来看，不处理也可以，但对于有洁癖的、追求完美的程序员而言这个是不允许的。具体处理步骤：
1.调整Tomcat对应类的log级别
修改${tomcat}/conf/log4j.properties
##解除类org.apache.jasper.compiler.TldLocationsCache的log org.apache.jasper.compiler.TldLocationsCache.level = FINE
2.观察Tomcat日志打印信息
步骤1执行完后，重启Tomcat，观察Tomcat日志，会在日志中发现类似如下打印信息：
九月 09, 2013 10:55:37 上午 org.apache.jasper.compiler.TldLocationsCache tldScanJar 详细: No TLD files were found in [file:/E:/devspace/xxt_login/WEB-INF/lib/json-lib-2.3-jdk15.jar]. Consider adding the JAR to the tomcat.util.scan.DefaultJarScanner.jarsToSkip or org.apache.catalina.startup.TldConfig.jarsToSkip property in CATALINA_BASE/conf/catalina.properties file. 九月 09, 2013 10:55:37 上午 org.apache.jasper.compiler.TldLocationsCache tldScanJar 详细: No TLD files were found in [file:/E:/devspace/xxt_login/WEB-INF/lib/poi-3.8.jar]. Consider adding the JAR to the tomcat.util.scan.DefaultJarScanner.jarsToSkip or org.apache.catalina.startup.TldConfig.jarsToSkip property in CATALINA_BASE/conf/catalina.properties file.
3.调整${tomcat}/conf/catalina.properties，将提示的jar添加到不扫描清单中
tomcat.util.scan.DefaultJarScanner.jarsToSkip=\ bootstrap.jar,commons-daemon.jar,tomcat-juli.jar,\ annotations-api.jar,el-api.jar,jsp-api.jar,servlet-api.jar,\ catalina.jar,catalina-ant.jar,catalina-ha.jar,catalina-tribes.jar,\ jasper.jar,jasper-el.jar,ecj-*.jar,\ tomcat-api.jar,tomcat-util.jar,tomcat-coyote.jar,tomcat-dbcp.jar,\ tomcat-jni.jar,tomcat-spdy.jar,\ tomcat-i18n-en.jar,tomcat-i18n-es.jar,tomcat-i18n-fr.jar,tomcat-i18n-ja.jar,\ tomcat-juli-adapters.jar,catalina-jmx-remote.jar,catalina-ws.jar,\ tomcat-jdbc.jar,\ tools.jar,\ commons-beanutils*.jar,commons-codec*.jar,commons-collections*.jar,\ commons-dbcp*.jar,commons-digester*.jar,commons-fileupload*.jar,\ commons-httpclient*.jar,commons-io*.jar,commons-lang*.jar,commons-logging*.jar,\ commons-math*.jar,commons-pool*.jar,\ jstl.jar,\ geronimo-spec-jaxrpc*.jar,wsdl4j*.jar,\ ant.jar,ant-junit*.jar,aspectj*.jar,jmx.jar,h2*.jar,hibernate*.jar,httpclient*.jar,\ jmx-tools.jar,jta*.jar,log4j*.jar,mail*.jar,slf4j*.jar,\ xercesImpl.jar,xmlParserAPIs.jar,xml-apis.jar,\ junit.jar,junit-*.jar,ant-launcher.jar,\ json-lib-*.jar,poi-*.jar
【注意】
1.如果使用eclipse server插件、Sysdeo tomcat插件启动Tomcat，此配合可能无效
2.步骤1调整完后，最好清除下以下两个文件夹${tomcat}/conf/Catalina ${tomcat}/work/Catalina
3.尽量使用*号实现模式匹配，以避免因jar版本升级带来的重复修改代价
【参考资料】
Servlet3.0新特性
http://blog.csdn.net/aking21alinjuju/article/details/5583820