android.os.Environment#MEDIA_REMOVED源码实例Demo

@Override
public StorageVolume[] getVolumeList(int uid, String packageName, int flags) {
    final int userId = UserHandle.getUserId(uid);

    final boolean forWrite = (flags & StorageManager.FLAG_FOR_WRITE) != 0;
    final boolean realState = (flags & StorageManager.FLAG_REAL_STATE) != 0;
    final boolean includeInvisible = (flags & StorageManager.FLAG_INCLUDE_INVISIBLE) != 0;

    final boolean userKeyUnlocked;
    final boolean storagePermission;
    final long token = Binder.clearCallingIdentity();
    try {
        userKeyUnlocked = isUserKeyUnlocked(userId);
        storagePermission = mStorageManagerInternal.hasExternalStorage(uid, packageName);
    } finally {
        Binder.restoreCallingIdentity(token);
    }

    boolean foundPrimary = false;

    final ArrayList<StorageVolume> res = new ArrayList<>();
    synchronized (mLock) {
        for (int i = 0; i < mVolumes.size(); i++) {
            final VolumeInfo vol = mVolumes.valueAt(i);
            switch (vol.getType()) {
                case VolumeInfo.TYPE_PUBLIC:
                case VolumeInfo.TYPE_EMULATED:
                    break;
                default:
                    continue;
            }

            boolean match = false;
            if (forWrite) {
                match = vol.isVisibleForWrite(userId);
            } else {
                match = vol.isVisibleForRead(userId)
                        || (includeInvisible && vol.getPath() != null);
            }
            if (!match) continue;

            boolean reportUnmounted = false;
            if ((vol.getType() == VolumeInfo.TYPE_EMULATED) && !userKeyUnlocked) {
                reportUnmounted = true;
            } else if (!storagePermission && !realState) {
                reportUnmounted = true;
            }

            final StorageVolume userVol = vol.buildStorageVolume(mContext, userId,
                    reportUnmounted);
            if (vol.isPrimary()) {
                res.add(0, userVol);
                foundPrimary = true;
            } else {
                res.add(userVol);
            }
        }
    }

    if (!foundPrimary) {
        Log.w(TAG, "No primary storage defined yet; hacking together a stub");

        final boolean primaryPhysical = SystemProperties.getBoolean(
                StorageManager.PROP_PRIMARY_PHYSICAL, false);

        final String id = "stub_primary";
        final File path = Environment.getLegacyExternalStorageDirectory();
        final String description = mContext.getString(android.R.string.unknownName);
        final boolean primary = true;
        final boolean removable = primaryPhysical;
        final boolean emulated = !primaryPhysical;
        final boolean allowMassStorage = false;
        final long maxFileSize = 0L;
        final UserHandle owner = new UserHandle(userId);
        final String uuid = null;
        final String state = Environment.MEDIA_REMOVED;

        res.add(0, new StorageVolume(id, path, path,
                description, primary, removable, emulated,
                allowMassStorage, maxFileSize, owner, uuid, state));
    }

    return res.toArray(new StorageVolume[res.size()]);
}
 

private static File prepareTargetDirectory() throws DownloadFailException, IOException {
    File downloadFolder =
            Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
    if (
            downloadFolder
                    != null
                    && (downloadFolder.exists() || downloadFolder.mkdir() || downloadFolder.createNewFile())
                    && downloadFolder.canWrite()
    ) {
        return downloadFolder;
    }

    File externalStorage = Environment.getExternalStorageDirectory();
    String externalStorageState = Environment.getExternalStorageState();
    if (
            externalStorage
                    != null
                    && (externalStorage.exists() || externalStorage.mkdir() || externalStorage.createNewFile())
                    && externalStorage.canWrite()
                    && externalStorageState.equals(Environment.MEDIA_MOUNTED)
    ) {
        return new File(externalStorage, "Download");
    }

    File appExternal = LMvdApp.getInstance().getExternalFilesDir(null);
    if (
            appExternal
                    != null
                    && (appExternal.exists() || appExternal.mkdir() || appExternal.createNewFile())
                    && appExternal.canWrite()
    ) {
        return new File(appExternal, "Download");
    }

    String message;
    switch (externalStorageState) {
        case Environment.MEDIA_UNMOUNTABLE:
            message = "External storage is un-mountable.";
            break;
        case Environment.MEDIA_SHARED:
            message = "USB mass storage is turned on. Can not mount external storage.";
            break;
        case Environment.MEDIA_UNMOUNTED:
            message = "External storage is not mounted.";
            break;
        case Environment.MEDIA_MOUNTED_READ_ONLY:
            message = "External storage is mounted but has no write access.";
            break;
        case Environment.MEDIA_BAD_REMOVAL:
            message = "External storage was removed without being properly ejected.";
            break;
        case Environment.MEDIA_REMOVED:
            message = "External storage does not exist. Probably removed.";
            break;
        case Environment.MEDIA_NOFS:
            message = "External storage is blank or has unsupported filesystem.";
            break;
        case Environment.MEDIA_CHECKING:
            message = "Still checking for external storage.";
            break;
        case Environment.MEDIA_EJECTING:
            message = "External storage is currently being ejected.";
            break;
        case Environment.MEDIA_UNKNOWN:
            message = "External storage is not available for some unknown reason.";
            break;
        case Environment.MEDIA_MOUNTED:
            message = "External storage is mounted but for some unknown reason is not" +
                    " available.";
            break;
        default:
            message = "External storage is not available. No reason.";
    }
    throw new DownloadFailException(message);
}