Android Sdcard文件操作之读、写、增、删（Kotlin实现）

Android Sdcard文件操作之读、写、增、删（Kotlin实现）

  在AndroidManifest.xml中加入访问SDCard的权限如下:

  PS：Android 6.0及以上的版本需要主动敏感申请权限。

一、读取Sdcard文件中的内容

/**
 * 读取Sdcard文件内容
 * @param context
 * @param filePathAndName 文件完整的路径，包含文件名，如"/sdcard/file.txt
 */
fun getContentFromSdcard(filePathAndName: String): String? {
    Log.d(TAG, "getContentFromSdcard filePathAndName: $filePathAndName")
    try {
        val fr = FileReader(filePathAndName)
        var bufReader: BufferedReader? = null
        try {
            if (null == fr) {
                return null
            }
            bufReader = BufferedReader(fr)
            var result = ""
            var line: String? = bufReader.readLine()
            while (line != null) {
                result += line
                line = bufReader.readLine()
            }
            LogUtils.d(TAG, "getContentFromSdcard result: $result")
            return result
        } catch (e: Exception) {
            e.printStackTrace()
        } finally {
            closeSilently(fr)
            closeSilently(bufReader)
        }
    } catch (e: FileNotFoundException) {
        e.printStackTrace()
    }

    return null
}

// IOUtils.java
public static void closeSilently(Closeable closeable) {
    if (closeable != null) {
        try {
            closeable.close();
        } catch (Exception e) {
        }
    }
}

二、向文件写内容

  向文件中写内容，可以分为两种情况：（1）、向指定文件写入指定的内容；（2）、复制文件，当然包括把需要复制文件的内容写入复制后生成的文件。

/**
 * 向指定文件写入指定内容
 */
fun write2File(destFileName: String, str: String) {
    LogUtils.d(TAG, "write2File destFileName: $destFileName content: $str")
    val fw = FileWriter(destFileName)

    try {
        fw.write(str)
    } catch (e: Exception) {
        e.printStackTrace()
    } finally {
        closeSilently(fw)
    }
}

/**
 * 复制文件
 */
fun copyFile2Dest(pathName: String, destName: String) {

    val fr = FileReader(File(pathName))
    val fw = FileWriter(File(destName))

    try {
        val buffer = CharArray(1024)
        var len = fr.read(buffer)
        while (len != -1) {
            fw.write(buffer, 0, len)
            len = fr.read(buffer)
        }
    } catch (e: Exception) {
        e.printStackTrace()
    } finally {
        closeSilently(fr)
        closeSilently(fw)
    }
}

/**
 * 复制Asset目录下的指定文件
 * @param assetName
 * @param sdcardFilePath 新文件
 */
fun copyAssetFile2SDCard(assetName: String, sdcardFilePath: String) {
    val context = DemoForActivityApplication.getInstance()
    val dbPath = addSlash(context.filesDir.path) + assetName
    val file = File(dbPath)
    if (file.exists()) {
        return
    }
    var inputStream: InputStream? = null
    var outputStream: FileOutputStream? = null
    try {
        val assetManager = context.assets
        inputStream = assetManager.open(assetName)
        outputStream = FileOutputStream(File(sdcardFilePath))

        val b = ByteArray(1024 * 5)
        var len: Int = inputStream!!.read(b)

        while (len != -1) {
            outputStream.write(b, 0, len)
            len = inputStream!!.read(b)
        }
        outputStream.flush()
    } catch (e: IOException) {
        e.printStackTrace()
    } finally {
        try {
            inputStream?.close()
            outputStream?.close()
        } catch (e: IOException) {
            e.printStackTrace()
        }

    }
}

三、删除文件

/**
 * 遍历删除指定文件或文件夹下面的文件
 */
private fun deleteDirectoryFiles(directory: File?) {
    if (directory == null || !directory.exists() || !directory.isDirectory) {
        LogUtils.d(TAG, "deleteFileByDirectory directory is null")
        return
    }
    if (directory != null && directory.exists() && directory.isDirectory) {
        for (listFile in directory.listFiles()) {
            if (listFile.isFile) {
                listFile.delete()
            } else if (listFile.isDirectory) {
                deleteDirectoryFiles(listFile)
            }
        }
    }
}

四、创建新文件

/**
 * 在指定目录下创建文件，若文件不存在，则创建；若已经存在，则不创建
 */
fun createNewFile(dirFile: File, fileName: String) {
    val file = File(dirFile, fileName)
    if (!file.exists()) {
        file.createNewFile()
    }
}