Scala学习——操作外部数据

scala操作外部数据

一、scala读取文件及网络数据

package top.ruandb.scala.Course08
import scala.io.Source
 
object FileApp {
  def main(args: Array[String]): Unit = {
    val FILEPATH = "D:\test\a.txt"
    val URL = "https://www.baidu.com"
    readLine(FILEPATH)
    readChar(FILEPATH)
    readNet(URL)
  }
  //按行读取文件
  def  readLine(path:String): Unit ={
    //通过Source类分fromFile方法读取文件
    val file = Source.fromFile("D:\test\a.txt")(scala.io.Codec.UTF8)
    for(line <- file.getLines()){
      println(line)
    }
  }
  //按char读取文件
  def readChar(path:String): Unit ={
    val file = Source.fromFile("D:\test\a.txt")(scala.io.Codec.UTF8)
    for(ele <- file){
      print(ele)
    }
  }
  //读取网络数据
  def readNet(url:String): Unit ={
    val file = Source.fromURL(url)(scala.io.Codec.UTF8)
    for(line <- file.getLines()){
      println(line)
    }
  }
}

二、scala读取mysql数据

package top.ruandb.scala.Course08
import java.sql.{Connection, DriverManager, ResultSet, Statement}
object MysqlApp {
  def main(args: Array[String]): Unit = {
    val url = "jdbc:mysql://192.168.44.181:3306/db_test"
    val username = "root"
    val password = "root"
 
    var connection:Connection = null
    var statement:Statement = null
    var resultSet:ResultSet = null
    try{
      classOf[com.mysql.jdbc.Driver]
      //获取连接
      connection = DriverManager.getConnection(url,username,password);
      statement = connection.createStatement();
      resultSet = statement.executeQuery(" select name,author ,price, publisher from book ")
      while(resultSet.next()){
        val name = resultSet.getString("name")
        val author =resultSet.getString("author")
        val price = resultSet.getString("price")
        val publisher = resultSet.getString("publisher")
        println(s"${name}  ${author}  ${price}  ${publisher}")
      }
    }catch {
      case e:Exception => println(e.printStackTrace())
    }finally {
      if(resultSet != null){
        resultSet.close()
      }
      if(statement != null){
        statement.close()
      }
      if(resultSet != null){
        resultSet.close()
      }
    }
  }
}

三、scala读取xml文件

package top.ruandb.scala.Course08
import java.io.FileInputStream
import scala.xml.XML
 
object XMLApp {
 
  def main(args: Array[String]): Unit = {
//    loadXml()
    readXmlAttr()
  }
 
  //读取完整的XML文件
  def loadXml(): Unit ={
    //通拓scala.xml.XML读取
//    val xml = XML.load(this.getClass.getClassLoader.getResource("test.xml"))
//    println(xml)
    val xml = XML.load(new FileInputStream("D:\IdeaProjects\scala02\src\test.xml"))
    println(xml)
  }
 
  //读取XML属性文件
  def readXmlAttr(): Unit ={
    val xml = XML.load(new FileInputStream("D:\IdeaProjects\scala02\src\test.xml"))
    //读取 header 下的 filed
    val headerFiled = xml  "header"  "field"
    println(headerFiled)//<field required="Y" name="a1">AAA</field><field required="Y" name="a2">BBB</field>
 
    //找所有的field
    val fields = xml \ "field"
    for(field <- fields){
      println(field)
    }
 
    //找header 下 field 的所有name
    //val headerFieldNames = (xml  "header"  "field" ).map(_  "@name")
    val headerFieldNames = xml  "header"  "field" \"@name" //两种都可以
    for(name <- headerFieldNames){
      println(name)
    }
 
    //找到name=ma1的message
    val mes = (xml \ "message").filter(x => (x "@name").text.equals("ma1"))
    for(me <- mes){
      println(me)
    }
  }
}