Hive的API操作

基于hadoop的Hive数据仓库JavaAPI简单调用的实例，关于Hive的简介在此不赘述。hive提供了三种用户接口：CLI，JDBC/ODBC和 WebUI

CLI，即Shell命令行
JDBC/ODBC 是 Hive 的Java，与使用传统数据库JDBC的方式类似
WebGUI是通过浏览器访问 Hive

本文主要介绍的就是第二种用户接口，直接进入正题。

1、Hive 安装：

1）hive的安装请参考网上的相关文章，测试时只在hadoop一个节点上安装hive即可。

2）测试数据data文件'\t'分隔：

1 zhangsan

2 lisi

3 wangwu

3）将测试数据data上传到linux目录下，我放置在：/home/hadoop01/data

2、在使用 JDBC 开发 Hive 程序时, 必须首先开启 Hive 的远程服务接口。使用下面命令进行开启:

    Java代码  
   
     收藏代码 
   
hive --service hiveserver >/dev/null 2>/dev/null &

3、测试代码：

    Java代码  
   
     收藏代码 
   
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import org.apache.log4j.Logger;

 
public class HiveJdbcCli { 
     
private static String driverName = "org.apache.hadoop.hive.jdbc.HiveDriver";
private static String url = "jdbc:hive://hadoop3:10000/default";
private static String user = "hive";
private static String password = "mysql";
private static String sql = "";
private static ResultSet res;
private static final Logger log = Logger.getLogger(HiveJdbcCli.class);
public static void main(String[] args) { 
     
Connection conn = null;
Statement stmt = null;
try { 
     
conn = getConn();
stmt = conn.createStatement();
// 第一步:存在就先删除
String tableName = dropTable(stmt);
// 第二步:不存在就创建
createTable(stmt, tableName);
// 第三步:查看创建的表
showTables(stmt, tableName);
// 执行describe table操作
describeTables(stmt, tableName);
// 执行load data into table操作
loadData(stmt, tableName);
// 执行 select * query 操作
selectData(stmt, tableName);
// 执行 regular hive query 统计操作
countData(stmt, tableName);
} catch (ClassNotFoundException e) { 
     
e.printStackTrace();
log.error(driverName + " not found!", e);
System.exit(1);
} catch (SQLException e) { 
     
e.printStackTrace();
log.error("Connection error!", e);
System.exit(1);
} finally { 
     
try { 
     
if (conn != null) { 
     
conn.close();
conn = null;
}
if (stmt != null) { 
     
stmt.close();
stmt = null;
}
} catch (SQLException e) { 
     
e.printStackTrace();
}
}
}
private static void countData(Statement stmt, String tableName)
throws SQLException { 
     
sql = "select count(1) from " + tableName;
System.out.println("Running:" + sql);
res = stmt.executeQuery(sql);
System.out.println("执行“regular hive query”运行结果:");
while (res.next()) { 
     
System.out.println("count ------>" + res.getString(1));
}
}
private static void selectData(Statement stmt, String tableName)
throws SQLException { 
     
sql = "select * from " + tableName;
System.out.println("Running:" + sql);
res = stmt.executeQuery(sql);
System.out.println("执行 select * query 运行结果:");
while (res.next()) { 
     
System.out.println(res.getInt(1) + "\t" + res.getString(2));
}
}
private static void loadData(Statement stmt, String tableName)
throws SQLException { 
     
String filepath = "/home/hadoop01/data";
sql = "load data local inpath '" + filepath + "' into table "
+ tableName;
System.out.println("Running:" + sql);
res = stmt.executeQuery(sql);
}
private static void describeTables(Statement stmt, String tableName)
throws SQLException { 
     
sql = "describe " + tableName;
System.out.println("Running:" + sql);
res = stmt.executeQuery(sql);
System.out.println("执行 describe table 运行结果:");
while (res.next()) { 
     
System.out.println(res.getString(1) + "\t" + res.getString(2));
}
}
private static void showTables(Statement stmt, String tableName)
throws SQLException { 
     
sql = "show tables '" + tableName + "'";
System.out.println("Running:" + sql);
res = stmt.executeQuery(sql);
System.out.println("执行 show tables 运行结果:");
if (res.next()) { 
     
System.out.println(res.getString(1));
}
}
private static void createTable(Statement stmt, String tableName)
throws SQLException { 
     
sql = "create table "
+ tableName
+ " (key int, value string) row format delimited fields terminated by '\t'";
stmt.executeQuery(sql);
}
private static String dropTable(Statement stmt) throws SQLException { 
     
// 创建的表名
String tableName = "testHive";
sql = "drop table " + tableName;
stmt.executeQuery(sql);
return tableName;
}
private static Connection getConn() throws ClassNotFoundException,
SQLException { 
     
Class.forName(driverName);
Connection conn = DriverManager.getConnection(url, user, password);
return conn;
}
}

4、测试结果

5、终端查询结果：

hive> select * from testHive;

1 zhangsan

2 lisi

3 wangwu

Time taken: 11.232 seconds

hive>

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