Alex 的 Hadoop 菜鸟教程: 第11课 Hive的Java调用
原文地址： http://blog.csdn.net/nsrainbow/article/details/43002387 最新课程请关注原作者博客，获得更好的显示体验
声明
- 本文基于Centos 6.x + CDH 5.x
说到Hive就一定要说到写程序的时候怎么调用Hive。以下我通过一个例子说明如果通过java来调用hive查询数据
数据准备
建立一个文本文件叫 a.txt，内容是
1,terry 2,alex 3,jimmy 4,mike 5,kate
并上传到hive服务器的 /data/ 目录下
JDBC调用方法
加载Driver
加载driver (只说hive2的jdbc)
Class.forName("org.apache.hive.jdbc.HiveDriver");
连接数据库
Connection con = DriverManager.getConnection("jdbc:hive2://host1:10000/default", "hive", "");
- 这里的 host1 是主机名
- 10000是hive默认的端口名
- default是默认的database
- hive是默认的用户名，默认密码是空
数据库操作语句
删除表
stmt.execute("drop table if exists " + tableName);
创建表
stmt.execute("create table " + tableName + " (key int, value string) ROW FORMAT DELIMITED FIELDS TERMINATED BY '\054'");
查询数据
ResultSet res = stmt.executeQuery("select * from " + tableName);
导入数据
stmt.execute("load data local inpath '" + filepath + "' into table " + tableName);
例子
建立项目
先打开eclipse建立一个maven项目
pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>org.crazycake</groupId> <artifactId>play-hive</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>play-hive</name> <url>http://maven.apache.org</url> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.8.1</version> <scope>test</scope> </dependency> <dependency> <groupId>org.apache.hive</groupId> <artifactId>hive-jdbc</artifactId> <version>0.14.0</version> </dependency> <dependency> <groupId>org.apache.hadoop</groupId> <artifactId>hadoop-common</artifactId> <version>2.2.0</version> </dependency> </dependencies> <build> <plugins> <plugin> <artifactId>maven-compiler-plugin</artifactId> <version>2.0.2</version> <configuration> <source>1.6</source> <target>1.6</target> <encoding>UTF-8</encoding> <optimise>true</optimise> <compilerArgument>-nowarn</compilerArgument> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-shade-plugin</artifactId> <version>2.3</version> <configuration> <transformers> <transformer implementation="org.apache.maven.plugins.shade.resource.ApacheLicenseResourceTransformer"> </transformer> </transformers> </configuration> <executions> <execution> <phase>package</phase> <goals> <goal>shade</goal> </goals> </execution> </executions> </plugin> </plugins> </build> </project>
其中最重要的就是这两段
<dependency> <groupId>org.apache.hive</groupId> <artifactId>hive-jdbc</artifactId> <version>0.14.0</version> </dependency> <dependency> <groupId>org.apache.hadoop</groupId> <artifactId>hadoop-common</artifactId> <version>2.2.0</version> </dependency>
其他的都无所谓
建表、导入以及查询数据
建立一个类 HiveJdbcClient
package org.crazycake.play_hive;
import java.sql.SQLException;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import java.sql.DriverManager;
/**
* 测试hive 的客户端连接
* @author alexxiyang (https://github.com/alexxiyang)
*
*/
public class HiveJdbcClient {
/**
* 注意：hive-server2 引用的driver是 org.apache.hive.* 而 hive-server 是 org.apache.hadoop.hive.*
*/
private static String driverName = "org.apache.hive.jdbc.HiveDriver";
/**
* @param args
* @throws SQLException
*/
public static void main(String[] args) throws SQLException {
try {
Class.forName(driverName);
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.exit(1);
}
//hive的默认端口是 10000，如果要修改就修改 hive-site.xml 文件的hive.server2.thrift.port 属性值
//默认用户名hive，默认密码为空
Connection con = DriverManager.getConnection("jdbc:hive2://host1:10000/default", "hive", "");
Statement stmt = con.createStatement();
//测试的表名 testhivedrivertable
String tableName = "testhivedrivertable";
//如果已经存在就删除
stmt.execute("drop table if exists " + tableName);
//创建这张表
stmt.execute("create table " + tableName + " (key int, value string) ROW FORMAT DELIMITED FIELDS TERMINATED BY '\054'");
//看下创建是否成功
String sql = "show tables '" + tableName + "'";
System.out.println("Running: " + sql);
ResultSet res = stmt.executeQuery(sql);
if (res.next()) {
System.out.println(res.getString(1));
}
//看下表结构
sql = "describe " + tableName;
System.out.println("Running: " + sql);
res = stmt.executeQuery(sql);
while (res.next()) {
System.out.println(res.getString(1) + "\t" + res.getString(2));
}
// 加载数据到表里面
// NOTE: filepath 是本地文件所在的位置，注意这个本地不是你的电脑！
// 你得先把这个文件上传到服务器，然后这里的路径是服务器上这个文件的路径
// NOTE: /data/a.txt
String filepath = "/data/a.txt";
sql = "load data local inpath '" + filepath + "' into table " + tableName;
System.out.println("Running: " + sql);
stmt.execute(sql);
// select * query
sql = "select * from " + tableName;
System.out.println("Running: " + sql);
res = stmt.executeQuery(sql);
while (res.next()) {
System.out.println(String.valueOf(res.getInt(1)) + "\t" + res.getString(2));
}
}
}
输出是
Running: show tables 'testhivedrivertable' testhivedrivertable Running: describe testhivedrivertable key int value string Running: load data local inpath '/data/a.txt' into table testhivedrivertable Running: select * from testhivedrivertable 1 terry 2 alex 3 jimmy 4 mike 5 kate Running: select count(1) from testhivedrivertable
其实java调用很简单的，就是把你在hive shell 里面执行的语句用jdbc执行一遍而已，所以你传输过去的语句的环境是hive server机器，里面写的路径也是从hive server主机的根目录路径出发去寻找数据，所以我们的 a.txt 得上传到服务器上，这段代码才会运行正常。
参考资料
- https://cwiki.apache.org/confluence/display/Hive/HiveServer2+Clients#HiveServer2Clients-JDBC