我已经在/usr/lib/sqoop/lib中添加了ojdbc.jar文件，我正在尝试使用sqoop将oracle连接到hadoop，但是遇到了错误。我正在使用以下命令：

sqoop list-tables --connect jdbc:oracle:thin://@192.162.2.8:1521:orcl  --username hr --password abc

但我得到以下错误：

15/05/05 09:21:31 WARN tool.BaseSqoopTool: Setting your password on the command-line is insecure. Consider using -P instead.
15/05/05 09:21:32 ERROR manager.OracleManager: Failed to rollback transaction
java.lang.NullPointerException
    at com.cloudera.sqoop.manager.OracleManager.listTables(OracleManager.java:596)
    at com.cloudera.sqoop.tool.ListTablesTool.run(ListTablesTool.java:49)
    at com.cloudera.sqoop.Sqoop.run(Sqoop.java:144)
    at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
    at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:79)
    at com.cloudera.sqoop.Sqoop.runSqoop(Sqoop.java:180)
    at com.cloudera.sqoop.Sqoop.runTool(Sqoop.java:218)
    at com.cloudera.sqoop.Sqoop.main(Sqoop.java:228)
15/05/05 09:21:32 ERROR manager.OracleManager: Failed to list tables
java.sql.SQLRecoverableException: IO Error: The Network Adapter could not establish the connection
    at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:489)
    at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:553)
    at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:254)
    at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:32)
    at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:528)
    at java.sql.DriverManager.getConnection(DriverManager.java:582)
    at java.sql.DriverManager.getConnection(DriverManager.java:185)
    at com.cloudera.sqoop.manager.OracleManager.makeConnection(OracleManager.java:275)
    at com.cloudera.sqoop.manager.GenericJdbcManager.getConnection(GenericJdbcManager.java:51)
    at com.cloudera.sqoop.manager.OracleManager.listTables(OracleManager.java:585)
    at com.cloudera.sqoop.tool.ListTablesTool.run(ListTablesTool.java:49)
    at com.cloudera.sqoop.Sqoop.run(Sqoop.java:144)
    at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
    at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:79)
    at com.cloudera.sqoop.Sqoop.runSqoop(Sqoop.java:180)
    at com.cloudera.sqoop.Sqoop.runTool(Sqoop.java:218)
    at com.cloudera.sqoop.Sqoop.main(Sqoop.java:228)
Caused by: oracle.net.ns.NetException: The Network Adapter could not establish the connection
    at oracle.net.nt.ConnStrategy.execute(ConnStrategy.java:439)
    at oracle.net.resolver.AddrResolution.resolveAndExecute(AddrResolution.java:454)
    at oracle.net.ns.NSProtocol.establishConnection(NSProtocol.java:693)
    at oracle.net.ns.NSProtocol.connect(NSProtocol.java:251)
    at oracle.jdbc.driver.T4CConnection.connect(T4CConnection.java:1140)
    at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:340)
    ... 16 more
Caused by: java.net.ConnectException: Connection refused
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:351)
    at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:213)
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:200)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
    at java.net.Socket.connect(Socket.java:529)
    at oracle.net.nt.TcpNTAdapter.connect(TcpNTAdapter.java:149)
    at oracle.net.nt.ConnOption.connect(ConnOption.java:133)
    at oracle.net.nt.ConnStrategy.execute(ConnStrategy.java:405)

sqoop命令有什么问题吗。？