Hive在Java中的jdbc使用

hive的本地模式和远程模式有什么区别

hive本质上是将sql语法解析为mapreduce的过程，既然如此它就必须提交mapreduce任务到resoucemanager，那么它如何提交？就是通过hadoop提供的命令hadoop jar命令来提交。

1. 本地模式：简单的理解，hive客户端仅供本地使用，直接使用hive命令，不需要指定IP 端口

2. 远程模式：简单的理解，将hive发布成一个服务进程，通过hive –service hiveserver命令，那么其hive客户端就可以连接hive的服务进程其他客户端可以是jdbc方式、hive提供的beeline命令等，既然要连接远端的hive服务进程，那自然需要指定IP 端口，这里的IP指的是hive服务进程所在的IP，端口自然也是，也自然与hadoop无关。所以不要混淆

hive的三种连接方式

1. hive 命令行模式

   hive –service cli

2. hive web界面的 (端口号9999) 启动方式

   hive –service hwi &

3. hive 远程服务 (端口号10000) 启动方式

   hive –service hiveserver &
   hive –service hiveserver -p 10002 (指定端口)

hive中jdbc使用

1. 创建表
   

   hive> create table employee(eid int, name String, dept String, yoj String)
   ROW FORMAT DELIMITED FIELDS TERMINATED BY “,”
   LINES TERMINATED BY “\n” STORED AS TEXTFILE;

2. 创建一个maven项目添加maven仓库依赖

<!-- https://mvnrepository.com/artifact/org.apache.hadoop/hadoop-common -->
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-common</artifactId>
            <version>2.7.1</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.apache.hadoop/hadoop-client -->
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-client</artifactId>
            <version>2.7.1</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.apache.hive/hive-jdbc -->
        <dependency>
            <groupId>org.apache.hive</groupId>
            <artifactId>hive-jdbc</artifactId>
            <version>1.2.1</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.apache.hive/hive-metastore -->
        <dependency>
            <groupId>org.apache.hive</groupId>
            <artifactId>hive-metastore</artifactId>
            <version>1.2.1</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.apache.hive/hive-metastore -->
        <dependency>
            <groupId>org.apache.hive</groupId>
            <artifactId>hive-exec</artifactId>
            <version>1.2.1</version>
        </dependency>

1. Java测试代理案列

 package com.hyg.hadoop.hive;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class HiveJdbcTest {

    private static String driverName = "org.apache.hive.jdbc.HiveDriver";

    public static void main(String[] args) throws SQLException {
        try {
            Class.forName(driverName);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
            System.exit(1);
        }

        Connection con = DriverManager.getConnection("jdbc:hive2://localhost:10000/default", "", "");
        Statement stmt = con.createStatement();
        String tableName = "employee";

        // describe table
        String sql = "describe " + tableName;
        System.out.println("Running: " + sql);
        ResultSet res = stmt.executeQuery(sql);
        while (res.next()) {
            System.out.println(res.getString(1) + "\t" + res.getString(2));
        }

        //load data
        sql = "load data local inpath '/root/employee.txt' overwrite into table      "+tableName;
        System.out.println("Running: " + sql);
        //stmt.executeQuery(sql);
        System.out.println("Load Data into "+tableName+" successful");

        //show table data
        sql = "select * from employee";
        System.out.println("Running: " + sql);
        res = stmt.executeQuery(sql);
        while (res.next()) {
            System.out.println(res.getString(1)+"--"+res.getString(2)+"--"+res.getString(3)+"--"+res.getString(4));
        }
    }

}

启动后台hiveserver遇见问题

Exception in thread "main" java.lang.ClassNotFoundException: org.apache.hadoop.hive.service.HiveServer
        at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:274)
        at org.apache.hadoop.util.RunJar.main(RunJar.java:205)
^C
[1]+  Exit 1                  hive --service hiveserver

解决办法： hive –service hiveserver2 使用hiveserver2

加载hive驱动报错

*驱动路径为：*org.apache.hive.jdbc.HiveDriver