Java 连接到impala错误连接被拒绝？

我正在尝试使用下面的驱动程序从Java程序连接到impala

com.cloudera.impala.jdbc4.Driver

但是我得到了一个sql异常，下面是堆栈跟踪

java.sql.SQLException: [Simba][ImpalaJDBCDriver](500310) Invalid operation: java.net.ConnectException: Connection refused: connect;
at com.cloudera.impala.hivecommon.api.HiveServer2ClientFactory.createTransport(HiveServer2ClientFactory.java:224)
at com.cloudera.impala.hivecommon.api.HiveServer2ClientFactory.createClient(HiveServer2ClientFactory.java:52)
at com.cloudera.impala.hivecommon.core.HiveJDBCConnection.connect(HiveJDBCConnection.java:597)
at com.cloudera.impala.jdbc.common.BaseConnectionFactory.doConnect(BaseConnectionFactory.java:219)
at com.cloudera.impala.jdbc.common.AbstractDriver.connect(AbstractDriver.java:216)
at java.sql.DriverManager.getConnection(Unknown Source)
at java.sql.DriverManager.getConnection(Unknown Source)
at com.gcs.virdict.InsertImpala.generateValue(InsertImpala.java:86)
Caused by: com.cloudera.impala.support.exceptions.GeneralException: [Simba][ImpalaJDBCDriver](500310) Invalid operation: java.net.ConnectException: Connection refused: connect;

我也附上下面的代码以供参考

private void connectionImpala() {
  try {  
    Class.forName(IMPALA_DRIVER_NAME);
  } catch (ClassNotFoundException e) {

    e.printStackTrace();
    System.exit(1);
  }
  Connection con = null;
  Statement stmt = null;
  try {
    con = DriverManager.getConnection( "jdbc:impala://IP:21050/default;user=abcde;password=abcde");
    stmt = con.createStatement();
    // ResultSet rs = stmt.executeQuery(sqlStatement)
  } catch (SQLException e) {
    e.printStackTrace();
  }

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sqlStatement变量的内容是什么？sqlStatement变量的内容是什么？