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這篇文章主要講解了“Android存儲訪問框架怎么使用”，文中的講解內容簡單清晰，易于學習與理解，下面請大家跟著小編的思路慢慢深入，一起來研究和學習“Android存儲訪問框架怎么使用”吧！
存儲訪問框架，簡稱：SAF， 就是系統文件選擇器+文件操作API。先選擇文件，在用文件操作API處理文件。系統文件選擇器，就和Windows的文件選擇框一樣。
其實絕大多數app,都不會使用這個東西，因為太不方便了。圖片，視頻，普通文件，需要用戶去翻文件夾找，這樣的用戶體驗實在太差了。所以大家都是用第三方的或者自己寫一個文件選擇器。
之所以講SAF，一，是因為Android11以后，使用MediaStore無法訪問到非多媒體文件了，需要依賴SAF了。二，外卡和SD卡的操作依賴于存儲訪問框架授權。
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/*"代碼所有類型的圖片。"*/*"代表所有類型的文件。
當只需要打開幾種文件類型時，可以用Intent.EXTRA_MIME_TYPES。同時setType設成“*/*”。
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，也可以打開文件選擇框。ACTION_GET_CONTENT更加寬泛，除了文件其他類型的內容還可以取。
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/*")下面列舉了所有的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"},
{"", "*/*"}
};利用DocumentsContract.EXTRA_INITIAL_URI，在打開文件選擇器的時候，跳轉到指定文件夾。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);當需要讀取非公共文件夾里面的文件時，可以申請授權，授權后保存Uri，之后可以拼接這個Uri操作文件夾里的所有文件。
尤其是SD卡，從Android 5 開始文件的修改刪除必須先授權，且必須通過SVF框架接口才能操作。
可以使用EXTRA_INITIAL_URI，打開指定文件夾，讓用戶授權
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，無法授權訪問存儲根目錄，以及Download/，Android/, 這兩個文件夾也無法授權。
創建文件夾有兩個情況，一個是在已授權的文件夾下，可以使用SVF框架API。
DocumentsContract.createDocument()
還有一種是在無授權的文件夾下創建，那么可以直接指定類型和名字，通過跳系統選擇框創建。
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)存儲訪問框架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.
*
* <p>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 {
}使用DocumentFile類獲取文件夾里文件列表。
private ActivityResultLauncher<Object> 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<Intent>() {
@Override
public void onActivityResult(Intent result) {
for (DocumentFile documentFile : DocumentFile.fromTreeUri(BaseApplication.getInstance().getApplicationContext(), Uri.parse(result.getData().toString())).listFiles()) {
Log.i("", documentFile.getUri());
}
}
});
}下面的代碼演示了，使用SVF讀取文件內容，寫內容，通過MediaStore查詢文件屬性。
private ActivityResultLauncher<Object> 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<Intent>() {
@Override
public 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 = 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)可以轉換，MediaStore Uri 和 Document Uri。通過MediaStore Uri中的數據庫id，就可以查詢文件的所有屬性了。
MediaStore Uri：content://media/external_primary/file/101750
Document Uri: content://com.android.externalstorage.documents/tree/primary%3AAuthSDK
另外，
非公共目錄下不能用File API操作的，即使通過SVF授權了， READ_EXTRNAL_PERMISSION的權限也給了。還是會拋出FileNotFoundException， 并且顯示permission deny。
存儲訪問框架API和MediaStore API的差異，在于存儲訪問框架API，是基于系統文件選擇框的，用戶選擇了文件，那么相當于授權了， 可以訪問所有類型的文件。而MediaStore的特點是可以查詢出所有文件，但是開啟分區存儲后，只能查處多媒體文件，其他類型文件是不可以的。
感謝各位的閱讀，以上就是“Android存儲訪問框架怎么使用”的內容了，經過本文的學習后，相信大家對Android存儲訪問框架怎么使用這一問題有了更深刻的體會，具體使用情況還需要大家實踐驗證。這里是億速云，小編將為大家推送更多相關知識點的文章，歡迎關注！
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