回调函数

Posted 2020-06-14

1、海南室分项目里用的比较多的 js回调函数  callback  查看 积累 文件

2、定义：

import java.sql.{ResultSet, DriverManager}

import com.dtgroup.sparkmr.configuration.DBConnection

/**
 * The package path is com.dtgroup.sparkmr.dao.
 * Created by tommy duan on 2016/1/4.
 */
class SQLExecute private {

def executeQuery(sql:String,callback:ResultSetCallback):Unit = {
    Class.forName(DBConnection.driver)
    val connection = DriverManager.getConnection(DBConnection.url, DBConnection.username, DBConnection.password)
    val statement = connection.createStatement()
    val resultSet = statement.executeQuery(sql)
    if (callback != null) {
      callback.call(resultSet);
    }
    resultSet.close()
    statement.close()
    connection.close()
  }
}
定义ResultSetCallback的接口

import java.sql.ResultSet

/**
 * The package path is com.dtgroup.sparkmr.dao.
 * Created by tommy duan on 2016/1/7.
 */
class ResultSetCallback {
  def call(resultSet:ResultSet):Unit={}
}
调用：

SQLExecute.executeQuery("select distinct CellOID, NeighborCellOID from Tuning.Res_NeighborCell order by CellOID", new ResultSetCallback {
  override def call(resultSet: ResultSet) = {
    if (!resultSet.wasNull()) {
      while (resultSet.next()) {
        val cellId = resultSet.getInt("CellOID")
        val neighborCellOID = resultSet.getInt("NeighborCellOID")
        if (!neighborCellMap.contains(cellId)) {
          neighborCellMap += (cellId -> List(neighborCellOID))
        }
        else {
          neighborCellMap(cellId).::(neighborCellOID)
        }
      }
    }
  }
})