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HIve的JavaAPI操作

分类: 文章 • 2024-03-11 13:27:43

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

  1. CLI，即Shell命令行
  2. JDBC/ODBC 是 Hive 的Java，与使用传统数据库JDBC的方式类似
  3. 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:

  

hive --service hiveserver >/dev/null 2>/dev/null &

 

 

 3、测试代码：

 

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;

/**
 * Hive的JavaApi
 * 
 * 启动hive的远程服务接口命令行执行：hive --service hiveserver >/dev/null 2>/dev/null &
 * 
 * @author 吖大哥
 * 
 */
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

HIve的JavaAPI操作

 

5、终端查询结果：

hive> select * from testHive;

OK

1       zhangsan

2       lisi

3       wangwu

Time taken: 11.232 seconds

hive> 

 

 

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