Java. Lang. classnotfoundexception: COM. MySQL. JDBC. Driver

Recently I learned about Servlet and used the MySQL database for development in eclipse. A strange problem is that if you deploy the project on the server, the following error is always reported: Java. Lang. classnotfoundexception: COM. MySQL. JDBC. Driver. In general, this problem occurs because no package is imported, but I imported the Java-connector into buildpath. If it is not running on the service, it runs correctly. It makes me very depressed. After thinking about it, maybe the import of web project packages is to paste the jar package to the lib directory, which is different from the normal javaproject.