scala连接mysql数据库

scala中通常是通过JDBC组件来连接Mysql。JDBC, 全称为Java DataBase Connectivity standard。

加载依赖

其中包含 JDBC driver

<dependency>
    <groupId>mysqlgroupId>
    <artifactId>mysql-connector-javaartifactId>
    <version>8.0.29version>
dependency>

1.1 spark组件直接连接（推荐）

通过spark.read直接连接，直接得到dataframe

val database = "test_db"
val table = "test_table"
val user = "hive"
val password  = "hive"
val url= "jdbc:mysql://localhost:10101/"+database

val jdbcDF = (spark.read.format("jdbc")
.option("url", url)
.option("dbtable", table)
.option("user", user)
.option("password", password) 
.option("driver", "com.mysql.cj.jdbc.Driver") 
.load())

jdbcDF.show()


+---+--------+
| id|   value|
+---+--------+
|  0|Record 0|
|  1|Record 1|
|  2|Record 2|
|  3|Record 3|
|  4|Record 4|
+---+--------+



//通过connectionProperties避免多次写入配置
val connectionProperties = new Properties()
connectionProperties.put("user", "username")
connectionProperties.put("password", "password")
val jdbcDF2 = spark.read
	//可增加.option("","")添加其他参数
  .jdbc(url, table , connectionProperties)
// Specifying the custom data types of the read schema
connectionProperties.put("customSchema", "id DECIMAL(38, 0), name STRING")
val jdbcDF3 = spark.read
  .jdbc(url, table , connectionProperties)

// 保存数据
jdbcDF.write
  .format("jdbc")
  .option("url", "jdbc:postgresql:dbserver")
  .option("dbtable", "schema.tablename")
  .option("user", "username")
  .option("password", "password")
  .save()
  
//或等价的：
jdbcDF2.write
  .jdbc(url, table , connectionProperties)

// Specifying create table column data types on write
jdbcDF.write
  .option("createTableColumnTypes", "name CHAR(64), comments VARCHAR(1024)")
  .jdbc(url, table , connectionProperties)
  
//通过query取数据
spark.read.format("jdbc")
.option("url", jdbcUrl)
.option("query", "select c1, c2 from t1")
.load()
//或放到properties里
connectionProperties.put("query", "select c1, c2 from t1")
spark.read
  .jdbc(url, table , connectionProperties)

注意：driver的类名根据不同的JDBC版本不同，早一些的版本为com.mysql.jdbc，而不是com.mysql.cj.jdbc.Driver。

2.1 jdbc api方法连接

还可通过 jdbc方法获取或保存数据

/**
  * Created by Administrator on 2017/12/23.
  */
import java.sql.{ Connection, DriverManager }


object ScalaJdbcConnectSelect extends App {


  // 访问本地MySQL服务器，通过3306端口访问mysql数据库
  val url = "jdbc:mysql://localhost:3306/cgjr?useUnicode=true&characterEncoding=utf-8&useSSL=false"
  //驱动名称
  val driver = "com.mysql.cj.jdbc.Driver"

  //用户名
  val username = "root"
  //密码
  val password = "12345"
  //初始化数据连接
  var connection: Connection = _
  try {
    //注册Driver
    Class.forName(driver)
    //得到连接
    connection = DriverManager.getConnection(url, username, password)
    val statement = connection.createStatement
    //执行查询语句，并返回结果
    val rs = statement.executeQuery("SELECT name, num FROM persons")//返回java.sql的ResultSet


    //打印返回结果
    while (rs.next) {
      val name = rs.getString("name")
      val num = rs.getString("num")
//      println(name+"\t"+num)
      println("name = %s, num = %s".format(name, num))
    }

    println("查询数据完成！")


    //    执行插入操作
    val rs2 = statement.executeUpdate("INSERT INTO `persons` (`name`, `num`) VALUES ('徐志摩', '22')")
    println("插入数据完成")


//    执行更新操作
    val rs3 = statement.executeUpdate("UPDATE persons set num=55 WHERE `name`=\"徐志摩\"")
    println("更新数据完成！")

//    执行删除操作

    val rs4 = statement.executeUpdate("delete from persons WHERE `name`=\"徐志摩\"")
    println("删除数据完成！")

//    执行调用存储过程操作
    val rs5 = statement.executeUpdate("call add_student(3)")
    println("调用存储过程完成！")


  } catch {
    case e: Exception => e.printStackTrace
  }
  //关闭连接，释放资源
  connection.close
}

参考

Spark Scala: Load Data from MySQL
【scala 数据库操作】scala操作mysql数据库
【官方】使用jdbc连接其他数据库