Scala文件操作实战详解

scala中遍历文件中的每一行必须导入scala.io.Source类：import scala.io.Source

• 使用Source.getLines返回的迭代器(只能调用一次，再次调用会清空)

val source = Source.fromFile("E://a.txt","UTF-8") val lines=source.getLines for(line <- lines )println(line)

• 将Source.getLines返回的迭代器转换成字数组

 val source = Source.fromFile("E://a.txt","UTF-8") val lines=source.getLines.toArray for（line <- lines ）println(line)

• 调用Source.makString，返回文本中的所有内容

val source = Source.fromFile("E://a.txt","UTF-8")val lines=source.mkString

使用Source对象之后，使用Source.close方法关闭IO流

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• 遍历文件中的每一个字符

val source = Source.fromFile("E://a.txt","UTF-8"for(i <- source)print(i)

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• 从URL以及字符串中读取字符

val html=Source.fromFile("http://www.baidu.com","UTF-8")html.mkString

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• 结合java的IO流，写文件(spark 中大量运用了java的多线程，spark是Scala和java共同编写而成，scala必须依赖于java的IO流读写文件)

import val file=new File("E://a.txt")val bytes=new Array[Bytes](file.length.toInt)val fis=new FileInputStream(file)fis.read(bytes)fis.lose()

val pw=new PrintWriter("E://a.txt")pw.println("Hello world")pw.close()

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• 递归遍历子目录

def getSubdir(dir:file):Iterator[file]={val childDir=dir.listFiles.filter(_.isDirectory)chilDirs.toIterator ++ childDirs.toIterator.flatMap(dubdirs _)}val iterator=subdirs(new file("E://a.txt"))for(a <- iterator)println(a)

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• 序列化和反序列化

@SerialVersionUID(42L) class Person(val name:String)extends Serializablval leo = new Person("leo")import java.io._val oos=new ObjectOutputStream (new FileOutputStream("e://a.txt"))oos.writeObject(leo)oos.close()val ois=new ObjectInputStean(new FileInputStream("e://b.txt"))val res=ois.readObject().asInstanceOf(Person)res.name