因为您使用

Since you tagged the question with tomcat, I'll assume that you're running a Java Servlet webapp.

在这种情况下，类路径涵盖了Webapp的/WEB-INF/lib 文件夹中的JAR文件以及/WEB-INF/classes 文件夹中的所有类文件Webapp的因此，您必须将第三方JAR文件和/或您的类放到那里，以使其在Web应用程序的运行时类路径中可见.

In that case, the classpath covers the JAR files in /WEB-INF/lib folder of the webapp and all class files in /WEB-INF/classes folder of the webapp. So you've to drop the 3rd party JAR files and/or your classes exactly there to get them to be visible in the runtime classpath of the webapp.

％CLASSPATH％环境变量被 java 可执行文件(不执行 -jar ， -cp 和 -classpath 参数.请勿将其用于网络应用程序.

The %CLASSPATH% environment variable is by the way ignored by everything else than the java executabele which is executed without -jar, -cp and -classpath arguments. Don't use it for webapps.