mysql問題：
com.mysql.jdbc.Driver not loaded. Are you sure you've included the correct jdbc driver in :jdbc_driver_library?
Unable to find driver class via URLClassLoader in given driver jars: com.mysql.jdbc.Driver and com.mysql.jdbc.Driver
解決方案：
可以嘗試將驅動器即mysql-connector-java-xxxx-bin.jar拷貝到 logstash目錄\logstash-core\lib\jars 下，上述問題就可解決。
oracle問題：
oracle.jdbc.driver.OracleDriver not loaded. Are you sure you've included the correct jdbc driver in :jdbc_driver_library
解決方案：
同理可以嘗試將驅動器即ojdbc6.jar拷貝到 logstash目錄\logstash-core\lib\jars 下，上述問題就可解決。如果還有問題修改配置
jdbc_driver_class => "Java::oracle.jdbc.driver.OracleDriver"
注意是首字母大寫，有兩個冒號Java::
還有問題可以查看logstash的jdbc連接文件註釋說明：
logstash-7.5.0\vendor\bundle\jruby\2.5.0\gems\logstash-input-jdbc-4.3.16\lib\logstash\plugin_mixins\jdbc\jdbc.rb
# JDBC driver library path to third party driver library. In case of multiple libraries being
# required you can pass them separated by a comma.
#
# If not provided, Plugin will look for the driver class in the Logstash Java classpath.
#翻譯：如果沒有提供，Plugin將在Logstash Java類路徑中查找驅動程序類
config :jdbc_driver_library, :validate => :string
# JDBC driver class to load, for exmaple, "org.apache.derby.jdbc.ClientDriver"
# NB per https://github.com/logstash-plugins/logstash-input-jdbc/issues/43 if you are using
# the Oracle JDBC driver (ojdbc6.jar) the correct `jdbc_driver_class` is `"Java::oracle.jdbc.driver.OracleDriver"`
#翻譯：Oracle JDBC驅動程序（ojdbc6.jar）正確的“JDBC驅動程序”是“Java::Oracle.JDBC.driver.OracleDriver”`
config :jdbc_driver_class, :validate => :string, :required => true