Java建立与断开数据库的连接，使用JAva建立数据库标识连接，加载驱动器、获取连接、获取DatabaseMetaData实例、获取数据库名称、获取数据库版本号、获取JDBC驱动器名称、获取驱动器版本号、获取登录用户名、关闭连接、输出出错信息等-Java to establish and disconnect the connection to the database, establishment of database identifier connection, load the drive to get a connection, obtain DatabaseMetaData instance, access to the database name, access to the database version number, access to JDBC driver device name, access to driver device version number, obtain the login user name using Java close the connection, the output error information