HIVE---HIve的JavaAPI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;

/**
* 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

5、终端查询结果：
hive> select * from testHive;
OK
1 zhangsan
2 lisi
3 wangwu
Time taken: 11.232 seconds
hive>