클래스를 찾을 수 없:예입니다.안녕하세요:java.랭.ClassNotFoundException java.랭.ClassNotFoundException:

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Find out which JAR file contains the problematic Java class. For example, in the case of com.mysql.jdbc.driver, the JAR file that contains it is mysql-connector-java.jar.
Check whether this JAR is present in the application classpath. If not, the JAR should be added to the classpath in Java and the application should be recompiled.
f that JAR is already present in the classpath, make sure the classpath is not overridden (e.g. by a start-up script). After finding out the exact Java classpath used by the application, the JAR file should be added to it.
To fix the Java exception, the mysql-connector JAR should be included in the application classpath.