英文:
Deleting a file given a Storage Access Framework uri and using content resolver fails
问题
我正在尝试使用“存储访问框架（Storage Access Framework）”来删除文件。
以下是一些代码元素：
public class MyActivity extends AppCompatActivity {
@Override
public boolean onOptionsItemSelected(MenuItem menuItem) {
int n_requestCode;
switch(menuItem.getItemId()) {
// ...
case R.id.delete_file:
n_requestCode = 108;
startSAFActionOpenDocumentTree(n_requestCode);
break;
// ...
}
// ...
}
public void startSAFActionOpenDocumentTree(int n_requestCode) {
Intent intent;
intent = new Intent(Intent.ACTION_OPEN_DOCUMENT_TREE);
startActivityForResult(intent, n_requestCode);
}
private void startSAFActionOpenDocument(int n_requestCode) {
Intent intent = null;
intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
intent.addCategory(Intent.CATEGORY_OPENABLE);
intent.setType("*/*");
startActivityForResult(intent, n_requestCode);
}
protected void onActivityResult(int n_requestCode, int n_resultCode, Intent data) {
android.net.Uri uri;
ContentResolver contentResolver;
if (n_requestCode == 108) {
n_requestCode = 109;
startSAFActionOpenDocument(n_requestCode);
} else if (n_requestCode == 109) {
uri = data.getData();
contentResolver = getContentResolver();
try {
contentResolver.delete(uri, null, null);
} catch (Exception exn) {
exn.printStackTrace();
}
}
}
}
因此，使用案例如下：
- 用户点击活动菜单中ID为
R.id.delete_file的条目。 - 然后用户必须选择一个目录
- 然后在此目录中选择一个文件。这是代码中检索到一个
android.net.Uri的地方。 - 给定此 URI，我想删除相应的文件。
问题如下：
contentResolver.delete(uri, null, null); 引发以下异常：
W/System.err: java.lang.UnsupportedOperationException: Delete not supported
at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:167)
at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:135)
at android.content.ContentProviderProxy.delete(ContentProviderNative.java:544)
at android.content.ContentResolver.delete(ContentResolver.java:1330)
at [...]MyActivity.onActivityResult(MyActivity.java:[...])
at android.app.Activity.dispatchActivityResult(Activity.java:6490)
at android.app.ActivityThread.deliverResults(ActivityThread.java:3695)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:3742)
at android.app.ActivityThread.access$1400(ActivityThread.java:150)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1393)
W/System.err: at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
请注意，代码的另一个位置，我使用 java.io.File 类的 delete() 方法，并且参数是文件路径（字符串），而不是 android.net.Uri，并且对于完全相同的文件，删除操作是可行的。
能否请您帮助我解决这个问题？谢谢。
英文:
I am trying to delete a file using Storage Access Framework.
Below are some elements of code:
public class MyActivity extends AppCompatActivity
{
@Override
public boolean onOptionsItemSelected(MenuItem menuItem)
{
int n_requestCode;
switch(menuItem.getItemId())
{
[...]
case R.id.delete_file:
n_requestCode = 108;
startSAFActionOpenDocumentTree(n_requestCode);
break;
[...]
}
[...]
}
public void startSAFActionOpenDocumentTree(int n_requestCode)
{
Intent intent;
intent = new Intent(Intent.ACTION_OPEN_DOCUMENT_TREE);
startActivityForResult(intent, n_requestCode);
}
private void startSAFActionOpenDocument(int n_requestCode)
{
Intent intent = null;
intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
intent.addCategory(Intent.CATEGORY_OPENABLE);
intent.setType("*/*");
startActivityForResult(intent, n_requestCode);
}
protected void onActivityResult(int n_requestCode, int n_resultCode, Intent data)
{
android.net.Uri uri;
ContentResolver contentResolver;
if(n_requestCode == 108)
{
n_requestCode = 109;
startSAFActionOpenDocument(n_requestCode);
}
else if(n_requestCode == 109)
{
uri = data.getData();
contentResolver = getContentResolver();
try
{
contentResolver.delete(uri, null, null);
}
catch(Exception exn)
{
exn.printStackTrace();
}
}
}
}
Hence, the use case is the following:
- The user taps the activity menu entry which id is
R.id.delete_file. - Then the user has to select a directory
- and then a file in this directory. This is where an
android.net.Uriis retrieved in the code. - Given this uri, I would like to delete the corresponding file.
The problem is the following:
The contentResolver.delete(uri, null, null); raises the following exception:
W/System.err: java.lang.UnsupportedOperationException: Delete not supported
at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:167)
at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:135)
at android.content.ContentProviderProxy.delete(ContentProviderNative.java:544)
at android.content.ContentResolver.delete(ContentResolver.java:1330)
at [...]MyActivity.onActivityResult(MyActivity.java:[...])
at android.app.Activity.dispatchActivityResult(Activity.java:6490)
at android.app.ActivityThread.deliverResults(ActivityThread.java:3695)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:3742)
at android.app.ActivityThread.access$1400(ActivityThread.java:150)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1393)
W/System.err: at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Note that, at another place in the code, I use the delete() method of the java.io.File class with an argument that is a file path (a String), not an android.net.Uri and the deletion works for the very same file.
Can you please help me solve that problem? Thanks.
答案1
得分: 4
操作不受支持是该消息。
请尝试改为：
DocumentFile srcDoc = DocumentFile.fromSingleUri(context, data.getData());
if (srcDoc.delete()) {
}
您的回答可能有效，但代码过于复杂。
此外，用户无需首先选择目录。
英文:
The operation is not supported is the message.
Try instead:
DocumentFile srcDoc = DocumentFile.fromSingleUri(context, data.getData());
if ( srcDoc.delete() )
{
}
Your answer may work but code is too complicated.
Also the user does not have to select the directory first.
答案2
得分: 2
我使用了DocumentFile类代替ContentResolver来找到这个解决方案。
文件已删除。
public class MyActivity extends AppCompatActivity
{
@Override
public boolean onOptionsItemSelected(MenuItem menuItem)
{
int n_requestCode;
switch(menuItem.getItemId())
{
[...]
case R.id.delete_file:
n_requestCode = 109;
startSAFActionOpenDocument(n_requestCode);
break;
[...]
}
[...]
}
private void startSAFActionOpenDocument(int n_requestCode)
{
Intent intent = null;
intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
intent.addCategory(Intent.CATEGORY_OPENABLE);
intent.setType("*/*");
startActivityForResult(intent, n_requestCode);
}
protected void onActivityResult(int n_requestCode, int n_resultCode, Intent data)
{
DocumentFile srcDoc;
if(n_requestCode == 109)
{
srcDoc = DocumentFile.fromSingleUri(this, data.getData());
try
{
srcDoc.delete();
}
catch(Exception exn)
{
exn.printStackTrace();
}
}
}
}
英文:
I found this solution using the class DocumentFile instead of ContentResolver.
The file is deleted.
public class MyActivity extends AppCompatActivity
{
@Override
public boolean onOptionsItemSelected(MenuItem menuItem)
{
int n_requestCode;
switch(menuItem.getItemId())
{
[...]
case R.id.delete_file:
n_requestCode = 109;
startSAFActionOpenDocument(n_requestCode);
break;
[...]
}
[...]
}
private void startSAFActionOpenDocument(int n_requestCode)
{
Intent intent = null;
intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
intent.addCategory(Intent.CATEGORY_OPENABLE);
intent.setType("*/*");
startActivityForResult(intent, n_requestCode);
}
protected void onActivityResult(int n_requestCode, int n_resultCode, Intent data)
{
DocumentFile srcDoc;
if(n_requestCode == 109)
{
srcDoc = DocumentFile.fromSingleUri(this, data.getData());
try
{
srcDoc.delete();
}
catch(Exception exn)
{
exn.printStackTrace();
}
}
}
}
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