用Java来开发Hive应用

1）预先配置

在hive配置文件：%HIVE_HOME%/conf/hive-site.xml添加

代码语言：javascript复制

<!-- 禁用 impersonation -->
<property>
    <name>hive.server2.enable.doAs</name>
    <value>false</value> 
</property>

在 Hadoop 的配置文件中%HADOOP_HOME%/etc/hadoo/下的：core-site.xml 和 hdfs-site.xml添加

代码语言：javascript复制

<property>
    <name>hadoop.proxyuser.root.groups</name>
    <value>*</value>
</property>
<property>
    <name>hadoop.proxyuser.root.hosts</name>
    <value>*</value>
</property>

确保没有设置限制 root 用户的权限

修改访问数据库表person的权限

代码语言：javascript复制

#hdfs dfs -chmod -R 775 /user/hive/warehouse/demo.db/person

由于Hive是数据仓库，而不是数据库，所以一般不支持增删改查，这里仅介绍如何通过Java来向Hive插入，查询数据。

2）代码

pom.xml文件

代码语言：javascript复制

<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.jerry</groupId>
  <artifactId>hive</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <description>Java How to connect Hivi</description>


    <dependencies>
        <!-- Hive JDBC Driver -->
        <dependency>
            <groupId>org.apache.hive</groupId>
            <artifactId>hive-jdbc</artifactId>
            <version>3.1.2</version>
        </dependency>


        <!-- Hadoop Common -->
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-common</artifactId>
            <version>3.2.2</version>
        </dependency>


        <!-- Hadoop Client -->
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-client</artifactId>
            <version>3.2.2</version>
        </dependency>
    </dependencies>
</project>

Java文件

代码语言：javascript复制

package com.jerry;

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

public class HiveClient {
    private static final String DRIVER_CLASS = "org.apache.hive.jdbc.HiveDriver";
    private static final String CONNECTION_URL = "jdbc:hive2://192.168.31.184:10000/demo";
    private static PreparedStatement preparedstatement;
    private static Statement statement;
    private static ResultSet resultSet = null;
    
    //链接
    private Connection getConnection() throws SQLException {
        try {
            Class.forName(DRIVER_CLASS);
            Connection con = DriverManager.getConnection(CONNECTION_URL);
            statement = con.createStatement();
            return con;
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
            throw new SQLException(e.getMessage());
        }
    }
    
    //断开链接
    public void disconnect(Connection con) throws SQLException {
       // Close resources
        resultSet.close();
        statement.close();
        con.close();
    }
    
    //执行查询
    public ResultSet query(String query) throws SQLException {
       // Execute a query
        ResultSet resultSet = statement.executeQuery(query);
        return resultSet;
    }
    
    //打印查询记录
    public void printQueryResult(ResultSet resultSet) throws SQLException {
       //获取 ResultSet 的元数据
        ResultSetMetaData metaData = resultSet.getMetaData();
        // 获取列数
        int columnCount = metaData.getColumnCount();
        while (resultSet.next()) {
           for (int i=1;i<=columnCount;i  ) {
             System.out.print(resultSet.getString(i) ",");
        }
        System.out.println("");
        }
    }
    
    //查询并且打印数据
    public void queryAndPrint(String query) throws SQLException {
      ResultSet resultSet = query(query);
      printQueryResult(resultSet);
    }
    
    //添加数据
    private void addDataToHiveTable(Connection con,String tableName,String[] newValue,String like,String map) {
        try {
          String insertSql = "INSERT INTO person SELECT ?,?,?," like "," map;
          preparedstatement = con.prepareStatement(insertSql);
          preparedstatement.setInt(1, Integer.parseInt(newValue[0]));
          preparedstatement.setString(2, newValue[1]);
          preparedstatement.setInt(3, Integer.parseInt(newValue[2]));
          preparedstatement.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    
public static void main(String[] args) throws SQLException {
        HiveClient hive = new HiveClient();
        String tableName = "person";
        String like = "array('basketball', 'music', 'dance')";
        String map = "map('address','xxxx')";
        String[] newAddValue = {"10","elite0","50"};
        Connection con = hive.getConnection();
        String query = "SELECT * FROM " tableName;
        try {  
        hive.queryAndPrint(query);
        hive.addDataToHiveTable(con,tableName,newAddValue,like,map);
        hive.queryAndPrint(query);
        hive.disconnect(con);
      } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
     }
   }
}

注意map，list处理要用Hive函数来处理。

开发 权限 数据 java hive

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