Java使用JDBC连接Hive（新版本）API封装

网上找了很多封装的API,发现都是过时了的，运行报各种错误，经过了几天的调错，终于可以使用java代码操作hive了

首先看看所需的包



所有的分析都在代码里面

注意：网上很多代码对于DDL都执行 res = stmt.executeQuery(sql);

这是错的，因为新版本DDL不能返回结果集，会报如下错误

java.sql.SQLException: The query did not generate a result set!

所以只能写 stmt.execute(sql);

它会返回一个boolean值

只有对于DML才能返回结果集

具体看下面的代码大家就懂了，不信的话大家可以试试，我的是1.1.1版本

package com.berg.hive.test1.api;

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 &
*
* @author 汤高
*
*/
public class HiveJdbcCli {
//网上写 org.apache.hadoop.hive.jdbc.HiveDriver ,新版本不能这样写
private static String driverName = "org.apache.hive.jdbc.HiveDriver";

//这里是hive2，网上其他人都写hive,在高版本中会报错
private static String url = "jdbc:hive2://master:10000/default";
private static String user = "hive";
private static String password = "hive";
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 {
//目录 ，我的是hive安装的机子的虚拟机的home目录下
String filepath = "user.txt";
sql = "load data local inpath '" + filepath + "' into table "
+ tableName;
System.out.println("Running:" + sql);
stmt.execute(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.execute(sql);
}

private static String dropTable(Statement stmt) throws SQLException {
// 创建的表名
String tableName = "testHive";
sql = "drop table  " + tableName;
stmt.execute(sql);
return tableName;
}

private static Connection getConn() throws ClassNotFoundException,
SQLException {
Class.forName(driverName);
Connection conn = DriverManager.getConnection(url, user, password);
return conn;
}

}

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