手机存储

手机分为内部存储和外部存储

1、内部存储

主要方法	路径
Environment.getDataDirectory()	/data
Environment.getDownloadCacheDirectory()	/cache
Environment.getRootDirectory()	/system

这里的内部存储对应的就是手机QQ的手机内存，路径为Environment.getDataDirectory().getParentFile()就是根目录，这个目录下还有一些私密的数据，比如：databases（数据库）、shared_prefs（SharedPreferences）等

注意：没有root的手机不能打开该文件夹的

2、外部存储

外部存储又分为SD卡和扩展卡内存

（1）SD卡

获取路径方式是Environment.getExternalStorageDirectory() /storage/sdcard0

方法	路径
Environment.getExternalStoragePublicDirectory(DIRECTORY_ALARMS)	/storage/sdcard0/Alarms
Environment.getExternalStoragePublicDirectory(DIRECTORY_DCIM)	/storage/sdcard0/DCIM
Environment.getExternalStoragePublicDirectory(DIRECTORY_DOWNLOADS)	/storage/sdcard0/Download
Environment.getExternalStoragePublicDirectory(DIRECTORY_MOVIES)	/storage/sdcard0/Movies
Environment.getExternalStoragePublicDirectory(DIRECTORY_MUSIC)	/storage/sdcard0/Music
Environment.getExternalStoragePublicDirectory(DIRECTORY_NOTIFICATIONS)	/storage/sdcard0/Notifications
Environment.getExternalStoragePublicDirectory(DIRECTORY_PICTURES)	/storage/sdcard0/Pictures
Environment.getExternalStoragePublicDirectory(DIRECTORY_PODCASTS)	/storage/sdcard0/Podcasts
Environment.getExternalStoragePublicDirectory(DIRECTORY_RINGTONES)	/storage/sdcard0/Ringtones

上面的九个方法对应的就是SD卡的九大公有目录，Google官方建议我们数据应该存储在私有目录下，不建议存储在公有目录下或其他地方

那什么是私有目录呢？

就是在外部存储的App的包名下，如：/storage/emulated/0/Android/data/cwj.test(包名)/files/test

方法	路径
getExternalFilesDir()	/storage/emulated/0/Android/data/cwj.test(包名)/files/test
getExternalCacheDir	/storage/emulated/0/Android/data/cwj.test(包名)/cache/test

一般情况下有包名的路径我们都是调用Context中的方法来获得，没有包名的路径，我们直接调用Environment中的方法获得。

（2）扩展卡内存

扩展内存就是我们插入的外置SD卡，获取扩展内存的路径有点难度：

private static String getExtendedMemoryPath(Context mContext) {  

      StorageManager mStorageManager = (StorageManager) mContext.getSystemService(Context.STORAGE_SERVICE);
        Class<?> storageVolumeClazz = null;
        try {
            storageVolumeClazz = Class.forName("android.os.storage.StorageVolume");
            Method getVolumeList = mStorageManager.getClass().getMethod("getVolumeList");
            Method getPath = storageVolumeClazz.getMethod("getPath");
            Method isRemovable = storageVolumeClazz.getMethod("isRemovable");
            Object result = getVolumeList.invoke(mStorageManager);
            final int length = Array.getLength(result);
            for (int i = 0; i < length; i++) {
                Object storageVolumeElement = Array.get(result, i);
                String path = (String) getPath.invoke(storageVolumeElement);
                boolean removable = (Boolean) isRemovable.invoke(storageVolumeElement);
                if (removable) {
                    return path;
                }
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }
        return null;
}