作者：snow_lyGirl
链接：https://blog.csdn.net/qq_31028313/article/details/125299445
来源：CSDN

小记一下

1、保存内容到文件及文件读取

/**
 * 保存信息到File
 * @param fileName 文件名
 * @param content 保存内容
 * @param mode 模式
 */
fun Context.saveIntoFile(
    fileName: String,
    content: String,
    mode: Int = Context.MODE_PRIVATE
): Boolean {
    return try {
        openFileOutput(fileName, mode).use {
            it.write(content.toByteArray())
            true
        }
    } catch (e: Exception) {
        false
    }
}
/**
 * 读取文件
 * @param fileName 文件名
 */
fun Context.readFromFile(fileName: String): String {
    val sb = StringBuilder()
    openFileInput(fileName).use {
        val temp = ByteArray(1024)
        var len = 0
        while (true) {
            len = it.read(temp)
            if (len <= 0) break
            sb.append(String(temp, 0, len))
        }
    }
    return sb.toString()
}

在Activity中使用

//保存
saveIntoFile(FILE_NAME, content)
//读取
val content = readFromFile(FILE_NAME)

2、保存内容到SD卡中的文件及SD卡文件读取

/**
 * 写文件到SD卡
 * eg:/storage/emulated/0/Android/data/com.guc.androiddemo/files/Documents/fileName
 * @param fileName 文件名
 * @param content 内容
 * @param type 文件类型
 *            {@link android.os.Environment#DIRECTORY_MUSIC},
 *            {@link android.os.Environment#DIRECTORY_PODCASTS},
 *            {@link android.os.Environment#DIRECTORY_RINGTONES},
 *            {@link android.os.Environment#DIRECTORY_ALARMS},
 *            {@link android.os.Environment#DIRECTORY_NOTIFICATIONS},
 *            {@link android.os.Environment#DIRECTORY_PICTURES}, or
 *            {@link android.os.Environment#DIRECTORY_MOVIES}.
 */
fun Context.saveFileToSD(
    fileName: String,
    content: String,
    type: String = Environment.DIRECTORY_DOCUMENTS
) {
    if (Environment.getExternalStorageState() == Environment.MEDIA_MOUNTED) {
        val fn = getExternalFilesDir(type)?.canonicalPath + "/" + fileName
        FileOutputStream(fn).use {
            it.write(content.toByteArray())
        }

    } else {
        throw Exception("没有存储卡")
    }
}

/**
 * 读取SD中文件
 * eg:/storage/emulated/0/Android/data/com.guc.androiddemo/files/Documents/fileName
 * @param fileName 文件名
 * @param type 文件类型-Documents
 */
fun Context.readFromSD(
    fileName: String,
    type: String = Environment.DIRECTORY_DOCUMENTS
): String {
    return if (Environment.getExternalStorageState() == Environment.MEDIA_MOUNTED) {
        val sb = StringBuilder()
        val fn = getExternalFilesDir(type)?.canonicalPath + "/" + fileName
        FileInputStream(fn).use {
            val temp = ByteArray(1024)
            var len = 0
            while (true) {
                len = it.read(temp)
                if (len <= 0) break
                sb.append(String(temp, 0, len))
            }
        }
        sb.toString()
    } else {
        throw Exception("没有存储卡")
    }
}

Activity中直接使用

//保存
saveFileToSD(FILE_NAME, content)
//读取
val content = readFromSD(FILE_NAME)

3、读取Raw文件

/**
 * 读取Raw文件中的内容
 * @param rawId Raw文件ID:R.id.info
 */
fun Context.readRaw(rawId: Int): String {
    return BufferedReader(InputStreamReader(resources.openRawResource(rawId))).use {
        val sb = StringBuilder()
        it.forEachLine { s ->
            sb.append(s)
        }
        sb.toString()
    }
}

4、读取Assets文件

/**
 * 读取Raw文件中的内容
 * @param rawId Raw文件ID:R.id.info
 */
fun Context.readRaw(rawId: Int): String {
    return BufferedReader(InputStreamReader(resources.openRawResource(rawId))).use {
        val sb = StringBuilder()
        it.forEachLine { s ->
            sb.append(s)
        }
        sb.toString()
    }
}

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本文链接：https://blog.zmonster.top/91.html

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