Impala样例程序指导

 // 所连接集群的认证模式是否在安全模式 
   boolean isSecureVer = false;

   // 定义HQL，不能包含“;” 
   String[] sqls = {"CREATE TABLE IF NOT EXISTS employees_info(id INT,name STRING)", 
            "SELECT COUNT(*) FROM employees_info", "DROP TABLE employees_info"}; 

// 拼接JDBC URL
StringBuilder sBuilder = new StringBuilder(
  "jdbc:hive2://").append("impalad_ip").append("/");

if (isSecurityMode) {
    // 安全模式
    sBuilder.append(";auth=")
            .append(clientInfo.getAuth())
            .append(";principal=")
            .append(clientInfo.getPrincipal())
            .append(";");
} else {
    // 普通模式
    sBuilder.append(";auth=noSasl");
}
String url = sBuilder.toString();

直连Impalad实例时，若当前连接的Impalad实例故障则会导致访问Impala失败。

   // 加载Hive JDBC驱动 
   Class.forName(HIVE_DRIVER);

 
   Connection connection = null; 
     try { 
       // 获取JDBC连接 
       // 第二个参数需要填写正确的用户名，否则会以匿名用户(anonymous)登录
       connection = DriverManager.getConnection(url, "userName", ""); 
          
       // 建表 
       // 表建完之后，如果要往表中导数据，可以使用LOAD语句将数据导入表中，比如从HDFS上将数据导入表: 
       //load data inpath '/tmp/employees.txt' overwrite into table employees_info; 
       execDDL(connection,sqls[0]); 
       System.out.println("Create table success!"); 
         
       // 查询 
       execDML(connection,sqls[1]); 
          
       // 删表 
       execDDL(connection,sqls[2]); 
       System.out.println("Delete table success!"); 
     } 
     finally { 
       // 关闭JDBC连接 
       if (null != connection) { 
         connection.close(); 
       } 
  
 public static void execDDL(Connection connection, String sql) 
   throws SQLException { 
     PreparedStatement statement = null; 
     try { 
       statement = connection.prepareStatement(sql); 
       statement.execute(); 
     } 
     finally { 
       if (null != statement) { 
         statement.close(); 
       } 
     } 
   } 
  
   public static void execDML(Connection connection, String sql) throws SQLException { 
     PreparedStatement statement = null; 
     ResultSet resultSet = null; 
     ResultSetMetaData resultMetaData = null; 
      
     try { 
       // 执行Impala SQL 
       statement = connection.prepareStatement(sql); 
       resultSet = statement.executeQuery(); 
        
       // 输出查询的列名到控制台 
       resultMetaData = resultSet.getMetaData(); 
       int columnCount = resultMetaData.getColumnCount(); 
       for (int i = 1; i <= columnCount; i++) { 
         System.out.print(resultMetaData.getColumnLabel(i) + '\t'); 
       } 
       System.out.println(); 
        
       // 输出查询结果到控制台 
       while (resultSet.next()) { 
         for (int i = 1; i <= columnCount; i++) { 
           System.out.print(resultSet.getString(i) + '\t'); 
         } 
         System.out.println(); 
       } 
     } 
     finally { 
       if (null != resultSet) { 
         resultSet.close(); 
       } 
        
       if (null != statement) { 
         statement.close(); 
       } 
     } 
   }