Android存储访问框架的使用小结

目录

  • 打开系统文件选择器与文件过滤
  • 打开指定文件夹
  • 文件夹权限申请
  • 创建文件夹
  • 存储访问框架API
  • 获取文件夹文件
  • 和MediaStore API的不同
存储访问框架,简称:SAF, 就是系统文件选择器+文件操作API。先选择文件,在用文件操作API处理文件。系统文件选择器,就和Windows的文件选择框一样。
其实绝大多数app,都不会使用这个东西,因为太不方便了。图片,视频,普通文件,需要用户去翻文件夹找,这样的用户体验实在太差了。所以大家都是用第三方的或者自己写一个文件选择器。
之所以讲SAF,一,是因为Android11以后,使用MediaStore无法访问到非多媒体文件了,需要依赖SAF了。二,外卡和SD卡的操作依赖于存储访问框架授权。

打开系统文件选择器与文件过滤
Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT); intent.addCategory(Intent.CATEGORY_OPENABLE); intent.setType("application/*"); startActivityForResult(intent, REQUEST_CODE)

setType的值是mime type, 可以是"image/*", "*/*",其中*是通配符。"image/*"代码所有类型的图片。"*/*"代表所有类型的文件。
当只需要打开几种文件类型时,可以用Intent.EXTRA_MIME_TYPES。同时setType设成“*/*”。
Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT); intent.addCategory(Intent.CATEGORY_OPENABLE); intent.setType("*/*"); intent.putExtra(Intent.EXTRA_MIME_TYPES, new String[] {"application/pdf", // .pdf"application/vnd.oasis.opendocument.text", // .odt"text/plain" // .txt}); startActivityForResult(intent, REQUEST_CODE)

Intent.ACTION_PICK和ACTION_GET_CONTENT,也可以打开文件选择框。ACTION_GET_CONTENT更加宽泛,除了文件其他类型的内容还可以取。
Intent intent = new Intent(Intent.ACTION_PICK,android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI); intent.setType("image/*");

Intent intent = new Intent(Intent.ACTION_GET_CONTENT); intent.setType("image/*")

下面列举了所有的mime type:
private static final String[][] MIME_TYPES = new String[][]{{"3gp", "video/3gpp"},{"apk", "application/vnd.android.package-archive"},{"asf", "video/x-ms-asf"},{"avi", "video/x-msvideo"},{"bin", "application/octet-stream"},{"bmp", "image/bmp"},{"c", "text/plain"},{"class", "application/octet-stream"},{"conf", "text/plain"},{"cpp", "text/plain"},{"doc", "application/msword"},{"docx", "application/vnd.openxmlformats-officedocument.wordprocessingml.document"},{"xls", "application/vnd.ms-excel"},{"xlsx", "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"},{"exe", "application/octet-stream"},{"gif", "image/gif"},{"gtar", "application/x-gtar"},{"gz", "application/x-gzip"},{"h", "text/plain"},{"htm", "text/html"},{"html", "text/html"},{"jar", "application/java-archive"},{"java", "text/plain"},{"jpeg", "image/jpeg"},{"jpg", "image/jpeg"},{"js", "application/x-JavaScript"},{"log", "text/plain"},{"m3u", "audio/x-mpegurl"},{"m4a", "audio/mp4a-latm"},{"m4b", "audio/mp4a-latm"},{"m4p", "audio/mp4a-latm"},{"ape", "audio/ape"},{"flac", "audio/flac"},{"m4u", "video/vnd.mpegurl"},{"m4v", "video/x-m4v"},{"mov", "video/quicktime"},{"mp2", "audio/x-mpeg"},{"mp3", "audio/x-mpeg"},{"mp4", "video/mp4"},{"mkv", "video/x-matroska"},{"flv", "video/x-flv"},{"divx", "video/x-divx"},{"mpa", "video/mpeg"},{"mpc", "application/vnd.mpohun.certificate"},{"mpe", "video/mpeg"},{"mpeg", "video/mpeg"},{"mpg", "video/mpeg"},{"mpg4", "video/mp4"},{"mpga", "audio/mpeg"},{"msg", "application/vnd.ms-outlook"},{"ogg", "audio/ogg"},{"pdf", "application/pdf"},{"png", "image/png"},{"pps", "application/vnd.ms-powerpoint"},{"ppt", "application/vnd.ms-powerpoint"},{"pptx", "application/vnd.openxmlformats-officedocument.presentationml.presentation"},{"prop", "text/plain"},{"rc", "text/plain"},{"rmvb", "audio/x-pn-realaudio"},{"rtf", "application/rtf"},{"sh", "text/plain"},{"tar", "application/x-tar"},{"tgz", "application/x-compressed"},{"txt", "text/plain"},{"wav", "audio/x-wav"},{"wma", "audio/x-ms-wma"},{"wmv", "audio/x-ms-wmv"},{"wps", "application/vnd.ms-works"},{"xml", "text/plain"},{"z", "application/x-compress"},{"zip", "application/x-zip-compressed"},{"rar", "application/x-rar"},{"", "*/*"}};


打开指定文件夹 利用DocumentsContract.EXTRA_INITIAL_URI,在打开文件选择器的时候,跳转到指定文件夹。只有android 8以上才行。
Uri uri = Uri.parse("content://com.android.externalstorage.documents/document/primary:Download"); Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT); intent.addCategory(Intent.CATEGORY_OPENABLE); intent.setType("*/*"); intent.putExtra(DocumentsContract.EXTRA_INITIAL_URI, uri); startActivityForResult(intent, 1);


文件夹权限申请 当需要读取非公共文件夹里面的文件时,可以申请授权,授权后保存Uri,之后可以拼接这个Uri操作文件夹里的所有文件。
尤其是SD卡,从Android 5 开始文件的修改删除必须先授权,且必须通过SVF框架接口才能操作。
可以使用EXTRA_INITIAL_URI,打开指定文件夹,让用户授权
Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT_TREE); Uri uri = Uri.parse("content://com.android.externalstorage.documents/document/primary:Download"); intent.putExtra(DocumentsContract.EXTRA_INITIAL_URI, uri); startActivityForResult(intent)

需要注意的是,Android 11以后,无法授权访问存储根目录,以及Download/,Android/, 这两个文件夹也无法授权。

创建文件夹 创建文件夹有两个情况,一个是在已授权的文件夹下,可以使用SVF框架API。
DocumentsContract.createDocument()

还有一种是在无授权的文件夹下创建,那么可以直接指定类型和名字,通过跳系统选择框创建。
Intent intent = new Intent(Intent.ACTION_CREATE_DOCUMENT); intent.addCategory(Intent.CATEGORY_OPENABLE); intent.setType("application/txt"); intent.putExtra(Intent.EXTRA_TITLE, "testfile.txt"); startActivityForResult(intent)


存储访问框架API 存储访问框架API,都在DocumentsContract里面,典型的有:
public static @Nullable Uri renameDocument(@NonNull ContentResolver content,@NonNull Uri documentUri, @NonNull String displayName) throws FileNotFoundException { } /*** Delete the given document.** @param documentUri document with {@link Document#FLAG_SUPPORTS_DELETE}* @return if the document was deleted successfully.*/public static boolean deleteDocument(@NonNull ContentResolver content, @NonNull Uri documentUri)throws FileNotFoundException { } /*** Copies the given document.** @param sourceDocumentUri document with {@link Document#FLAG_SUPPORTS_COPY}* @param targetParentDocumentUri document which will become a parent of the source*document's copy.* @return the copied document, or {@code null} if failed.*/public static @Nullable Uri copyDocument(@NonNull ContentResolver content,@NonNull Uri sourceDocumentUri, @NonNull Uri targetParentDocumentUri)throws FileNotFoundException { } /*** Moves the given document under a new parent.** @param sourceDocumentUri document with {@link Document#FLAG_SUPPORTS_MOVE}* @param sourceParentDocumentUri parent document of the document to move.* @param targetParentDocumentUri document which will become a new parent of the source*document.* @return the moved document, or {@code null} if failed.*/public static @Nullable Uri moveDocument(@NonNull ContentResolver content,@NonNull Uri sourceDocumentUri, @NonNull Uri sourceParentDocumentUri,@NonNull Uri targetParentDocumentUri) throws FileNotFoundException { } /*** Removes the given document from a parent directory.** In contrast to {@link #deleteDocument} it requires specifying the parent.* This method is especially useful if the document can be in multiple parents.** @param documentUri document with {@link Document#FLAG_SUPPORTS_REMOVE}* @param parentDocumentUri parent document of the document to remove.* @return true if the document was removed successfully.*/public static boolean removeDocument(@NonNull ContentResolver content, @NonNull Uri documentUri,@NonNull Uri parentDocumentUri) throws FileNotFoundException { }


获取文件夹文件 使用DocumentFile类获取文件夹里文件列表。
private ActivityResultLauncher openFile() {Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT_TREE); Uri uri = Uri.parse("content://com.android.externalstorage.documents/document/primary:AuthSDK"); intent.putExtra(DocumentsContract.EXTRA_INITIAL_URI, uri); return startActivityForResult(intent, new ActivityResultCallback() {@Overridepublic void onActivityResult(Intent result) { for (DocumentFile documentFile : DocumentFile.fromTreeUri(BaseApplication.getInstance().getApplicationContext(), Uri.parse(result.getData().toString())).listFiles()) { Log.i("", documentFile.getUri()); }}}); }
【Android存储访问框架的使用小结】下面的代码演示了,使用SVF读取文件内容,写内容,通过MediaStore查询文件属性。
private ActivityResultLauncher openFile() {Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT_TREE); Uri uri = Uri.parse("content://com.android.externalstorage.documents/document/primary:AuthSDK"); intent.putExtra(DocumentsContract.EXTRA_INITIAL_URI, uri); return startActivityForResult(intent, new ActivityResultCallback() {@Overridepublic void onActivityResult(Intent result) { for (DocumentFile documentFile : DocumentFile.fromTreeUri(BaseApplication.getInstance().getApplicationContext(), Uri.parse(result.getData().toString())).listFiles()) {try {InputStream inputStream = BaseApplication.getInstance().getContentResolver().openInputStream(documentFile.getUri()); byte[] readData = https://www.it610.com/article/new byte[1024]; inputStream.read(readData); OutputStream outputStream = BaseApplication.getInstance().getContentResolver().openOutputStream(documentFile.getUri()); byte[] writeData ="alan gong".getBytes(StandardCharsets.UTF_8); outputStream.write(writeData, 0, 9); outputStream.close(); if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {Uri mediaUri = MediaStore.getMediaUri(BaseApplication.getInstance().getApplicationContext(), documentFile.getUri()); long fileId = ContentUris.parseId(mediaUri); Cursor query = BaseApplication.getInstance().getContentResolver().query(documentFile.getUri(), null, MediaStore.MediaColumns._ID + "=" + fileId, null, null); int columnIndex = query.getColumnIndexOrThrow(MediaStore.MediaColumns.MIME_TYPE); String mimeType = query.getString(columnIndex); Log.i("", ""); } } catch (FileNotFoundException e) {e.printStackTrace(); } catch (IOException e) {e.printStackTrace(); }}}}); }
使用MediaStore.getMediaUri(documentUri)可以转换,MediaStore Uri 和 Document Uri。通过MediaStore Uri中的数据库id,就可以查询文件的所有属性了。
MediaStore Uri:content://media/external_primary/file/101750
Document Uri: content://com.android.externalstorage.documents/tree/primary%3AAuthSDK
另外,
非公共目录下不能用File API操作的,即使通过SVF授权了, READ_EXTRNAL_PERMISSION的权限也给了。还是会抛出FileNotFoundException, 并且显示permission deny。
Android存储访问框架的使用小结
文章图片


和MediaStore API的不同 存储访问框架API和MediaStore API的差异,在于存储访问框架API,是基于系统文件选择框的,用户选择了文件,那么相当于授权了, 可以访问所有类型的文件。而MediaStore的特点是可以查询出所有文件,但是开启分区存储后,只能查处多媒体文件,其他类型文件是不可以的。
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