[Android][Kotlin]从文件中读取数据
程序员文章站
2022-03-08 20:51:03
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1.示例代码:
private fun load() { var fileInputStream = openFileInput("data") //把文件内容读取进缓冲读取器(use方法会自动对BufferedReader进行关闭) BufferedReader(InputStreamReader(fileInputStream)).use { var line: String while (true) { line = it.readLine() ?: break //当有内容时读取一行数据,否则退出循环 println(line) //打印一行数据 } } } } }
2.注意事项:
kotlin读取文件有多种方法,但是读取本地/data/data/.../files里的文件,必须要用fileInputStream
要不会出现Permission Denie错误.
那么kotlin读取文件有什么方法呢?一种是上面的方法,其次
第一种:
fun main(args: Array<String>) { val file = File("build.gradle") //新建文件读取build.gradle的内容 //把文件内容读取进缓冲读取器 val bufferedReader = BufferedReader(FileReader(file)) var line: String while (true) { //当有内容时读取一行数据,否则退出循环 line = bufferedReader.readLine() ?: break println(line) //打印一行数据 } bufferedReader.close() //关闭缓冲读取器 }
第二种:
fun main(args: Array<String>) { //最简单打印文件内容的方法,readLines()方法可读取文件内容 File("build.gradle").readLines().forEach(::println) }
以上两种都会出现权限问题.
参考:https://*.com/questions/2022256/permission-denied-file-created-in-files
Easiest way to open the file (and create it at the same time) would be to use the openFileOutput("file.txt", MODE_PRIVATE) method. This ensures that the file is only readable by your application (the same as you've have at the moment), plus it returns you a FileOutputStream so you can start writing to it.
参考:https://www.jianshu.com/p/832b19b8a025
写入数据参见另一篇博文:http://jameskaron.iteye.com/admin/blogs/2423085
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