Scalaカスタムデータベース接続プールおよびツールクラス

import java.sql.{Connection, DriverManager, PreparedStatement, ResultSet, Statement}
import java.util.concurrent.{BlockingQueue, LinkedBlockingQueue}

/**
  * JDBC    
  * @author Created by CN on 2018/12/5/0005 11:09 .
  */
class DBUtil {

  private var connection: Connection = _
  
  private var preparedStatement: PreparedStatement = _

  private var resultSet: ResultSet = _
  
  
  /**
    *      SQL
    * @param sql      sql
    */
  def execute(sql: String): Unit = {
    try {
      this.connection = DBUtil.getConnection
      this.preparedStatement = this.connection.prepareStatement(sql)
      this.preparedStatement.execute()
    } catch {
      case e: Exception => e.printStackTrace()
    } finally {
      DBUtil.returnConnection(this.connection)
      this.connection == null
    }
  }
  
  /**
    *          
    * @param sql
    * @param objects
    * @return
    */
  def insertForGeneratedKeys(sql: String, objects: Array[Any]): ResultSet = {
    try {
      this.connection = DBUtil.getConnection
      this.preparedStatement = this.connection.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS)
      if(objects != null)
        this.setPreparedStatement(objects)
      
      this.preparedStatement.executeUpdate()
      this.resultSet = preparedStatement.getGeneratedKeys
    } catch {
      case e: Exception => e.printStackTrace()
    } finally {
      DBUtil.returnConnection(this.connection)
      this.connection == null
    }
  
    this.resultSet
  }
  
  /**
    *     
    * @param sql      sql
    * @param objects   
    * @return
    */
  def executeQuery(sql: String, objects: Array[Any]): ResultSet = {
    try {
      this.connection = DBUtil.getConnection
      this.preparedStatement = this.connection.prepareStatement(sql)
      if(objects != null)
        this.setPreparedStatement(objects)
      
      this.resultSet = this.preparedStatement.executeQuery()
    } catch {
      case e: Exception => e.printStackTrace()
    } finally {
      DBUtil.returnConnection(this.connection)
      this.connection == null
    }
  
    this.resultSet
  }
  
  /**
    *     /    
    * @param sql
    * @param objects
    * @return      ，  -1     
    */
  def executeInsertOrUpdate(sql: String, objects: Array[Any]): Int = {
    try {
      this.connection = DBUtil.getConnection
      this.preparedStatement = this.connection.prepareStatement(sql)
      if(objects != null)
        this.setPreparedStatement(objects)
    
      this.preparedStatement.executeUpdate()
    } catch {
      case e: Exception => e.printStackTrace()
    } finally {
      DBUtil.returnConnection(this.connection)
      this.connection == null
    }
    
    -1
  }
  
  /**
    *           preparedStatement      
    * @param objects
    */
  private def setPreparedStatement(objects: Array[Any]): Unit = {
    var i = 1
    for(obj  e.printStackTrace()
    }
  }
  
  /**
    *     
    */
  def close() : Unit = {
    try {
      if(resultSet != null) resultSet.close()
      if(preparedStatement != null) preparedStatement.close()
//      if(connection != null) connection.close()
    } catch {
      case e: Exception => e.printStackTrace()
    }
  }
}



/**
  * JDBC    
  *       config/db.properties    
  * @author Created by CN on 2018/11/9 17:37
  */
object DBUtil {
  
  private val propertiesUtil = new PropertiesUtil("config/db.properties")
  
  //       
  private val driverClass: String = propertiesUtil.readPropertyByKey("driverClass")
  //        
  private val url: String = propertiesUtil.readPropertyByKey("url")
  //         
  private val username: String = propertiesUtil.readPropertyByKey("userName")
  //        
  private val password: String = propertiesUtil.readPropertyByKey("password")
  
  //        
  Class.forName(driverClass)
  
  //      
  val poolSize: Int = propertiesUtil.readPropertyByKey("poolSize").toInt
  
  //     -     
  private val pool: BlockingQueue[Connection]  = new LinkedBlockingQueue[Connection]()
  
  /**
    *       
    */
  for(i  0) {
        try {
//          println(s"       : ${DBUtil.pool.size}")
          DBUtil.pool.take().close()
        } catch {
          case e: Exception => e.printStackTrace()
        }
      }
    }
  }
}

driverClass = com.mysql.jdbc.Driver
url = jdbc:mysql://localhosst:3306/test?useSSL=false&useUnicode=true&characterEncoding=utf8
userName = root
password = root
poolSize = 10