首先ranger和hive是通过在hive中配置hive.security.authorization.manager参数，建立起的联系

在hive的lib目录下存在ranger-plugin-classloader-0.5.0.2.4.0.0-169.jar、ranger-hive-plugin-shim-0.5.0.2.4.0.0-169.jar这两jar包以及ranger-hive-plugin-impl目录

当实例化hive.security.authorization.manager指定的类时(org.apache.ranger.authorization.hive.authorizer.RangerHiveAuthorizerFactory)，也就是调用RangerHiveAuthorizerFactory的构造方法时，会调用RangerHiveAuthorizerFactory的init()方法；在RangerHiveAuthorizerFactory的init()中，会调用ranger-plugin-classloader-0.5.0.2.4.0.0-169.jar包中的RangerPluginClassLoader的getInstance方法，来获取自定义的URLClassLoader；在ranger-plugin-classloader-0.5.0.2.4.0.0-169.jar包中实现了RangerPluginClassLoader类，该类继承自URLClassLoader；使用RangerPluginClassLoaderUtil类getPluginFilesForServiceTypeAndPluginclass方法，根据组件名生成路径(路径如：/usr/hdp/2.4.0.0-169/hive/lib/ranger-hive-plugin-impl)；然后获取该路径(/usr/hdp/2.4.0.0-169/hive/lib/ranger-hive-plugin-impl)下的所有jar包的URL

[file:/usr/hdp/2.4.0.0-169/hive/lib/ranger-hive-plugin-impl/ranger-plugins-cred-0.5.0.2.4.0.0-169.jar, file:/usr/hdp/2.4.0.0-169/hive/lib/ranger-hive-plugin-impl/noggit-0.6.jar, file:/usr/hdp/2.4.0.0-169/hive/lib/ranger-hive-plugin-impl/eclipselink-2.5.2-M1.jar, file:/usr/hdp/2.4.0.0-169/hive/lib/ranger-hive-plugin-impl/ranger_solrj-0.5.0.2.4.0.0-169.jar, file:/usr/hdp/2.4.0.0-169/hive/lib/ranger-hive-plugin-impl/ranger-plugins-audit-0.5.0.2.4.0.0-169.jar, file:/usr/hdp/2.4.0.0-169/hive/lib/ranger-hive-plugin-impl/httpmime-4.2.5.jar, file:/usr/hdp/2.4.0.0-169/hive/lib/ranger-hive-plugin-impl/gson-2.2.4.jar, file:/usr/hdp/2.4.0.0-169/hive/lib/ranger-hive-plugin-impl/javax.persistence-2.1.0.jar, file:/usr/hdp/2.4.0.0-169/hive/lib/ranger-hive-plugin-impl/ranger-hive-plugin-0.5.0.2.4.0.0-169.jar, file:/usr/hdp/2.4.0.0-169/hive/lib/ranger-hive-plugin-impl/ranger-plugins-common-0.5.0.2.4.0.0-169.jar]

调用super方法，将这些jar包的URL传入URLClassLoader子类中，并返回RangerPluginClassLoader实例(在RangerPluginClassLoader类中实现了findClass、loadClass、findResource、findResources方法)

注意：本文归作者所有，未经作者允许，不得转载