topics/providers/document-provider.jd

page.title=
@jd:body
<div id="qv-wrapper">
<div id="qv">

<h2>
 <a href="#" onclick="hideNestedItems('#toc44',this);return false;" class="header-toggle">
        <span class="more"></span>
        <span class="less" style="display:none"></span></a></h2>
<ol id="toc44" class="hide-nested">
    <li>
        <a href="#overview"></a>
    </li>
    <li>
        <a href="#flow"> </a>
    </li>
    <li>
        <a href="#client"> </a>
        <ol>
        <li><a href="#search"></a></li>
        <li><a href="#process"></a></li>
        <li><a href="#metadata"> </a></li>
        <li><a href="#open"></a></li>
        <li><a href="#create"></a></li>
        <li><a href="#delete"></a></li>
        <li><a href="#edit"></a></li>
        <li><a href="#permissions"></a></li>
        </ol>
    </li>
    <li><a href="#custom">  </a>
        <ol>
        <li><a href="#manifest"></a></li>
        <li><a href="#contract"></a></li>
        <li><a href="#subclass"> DocumentsProvider</a></li>
        <li><a href="#security"></a></li>
        </ol>
    </li>

</ol>
<h2></h2>
<ol>
    <li>{@link android.provider.DocumentsProvider}</li>
    <li>{@link android.provider.DocumentsContract}</li>
</ol>

<h2></h2>

<ol>
    <li><a href="http://www.youtube.com/watch?v=zxHVeXbK1P4">
DevBytes: Android 4.4   : </a></li>
     <li><a href="http://www.youtube.com/watch?v=UFj9AEz0DHQ">
DevBytes: Android 4.4   : </a></li>
</ol>


<h2></h2>

<ol>
    <li><a href="{@docRoot}samples/StorageProvider/index.html">
StorageProvider</a></li>
     <li><a href="{@docRoot}samples/StorageClient/index.html">
StorageClient</a></li>
</ol>

<h2></h2>
<ol>
    <li>
        <a href="{@docRoot}guide/topics/providers/content-provider-basics.html">                 </a>


    </li>
</ol>

</div>
</div>


<p>Android 4.4 API  19  SAFSAF

 UI
</p>

<p> {@link android.provider.DocumentsProvider}
 SAF

</p>

<p>SAF </p>

<ul>
<li><strong> </strong>&mdash; Google
  {@link android.provider.DocumentsProvider} document-provider  Android


</li>

<li><strong> </strong>&mdash;{@link android.content.Intent#ACTION_OPEN_DOCUMENT}  {@link android.content.Intent#ACTION_CREATE_DOCUMENT}


</li>

<li><strong></strong>&mdash;  UI
</li>
</ul>

<p>SAF </p>
<ul>
<li> 1  </li>
<li>

</li>
<li>  USB
 </li>
</ul>

<h2 id ="overview"></h2>

<p>SAF {@link android.provider.DocumentsProvider}
 <em></em>
</p>
<p><img src="{@docRoot}images/providers/storage_datamodel.png" alt="data model" /></p>
<p class="img-caption"><strong> 1.</strong>   1
</p>

<p>: </p>
<ul>

<li>  1  {@link android.provider.DocumentsContract.Root#COLUMN_ROOT_ID}  USB


</li>

<li> 1 1  <em>N</em>  1  <em>N</em>
 </li>

<li>  {@link android.provider.DocumentsContract.Document#COLUMN_DOCUMENT_ID}  URI  ID


</li>


<li> MIME {@link android.provider.DocumentsContract.Document#MIME_TYPE_DIR} MIME

</li>

<li>{@link android.provider.DocumentsContract.Document#COLUMN_FLAGS COLUMN_FLAGS} {@link android.provider.DocumentsContract.Document#FLAG_SUPPORTS_WRITE}{@link android.provider.DocumentsContract.Document#FLAG_SUPPORTS_DELETE}{@link android.provider.DocumentsContract.Document#FLAG_SUPPORTS_THUMBNAIL}  {@link android.provider.DocumentsContract.Document#COLUMN_DOCUMENT_ID}


</li>
</ul>

<h2 id="flow"> </h2>
<p>
{@link android.provider.DocumentsProvider} API

</p>

<p> 2  SAF
</p>
<p><img src="{@docRoot}images/providers/storage_dataflow.png" alt="app" /></p>

<p class="img-caption"><strong> 2.</strong>    </p>

<p>: </p>
<ul>

<li>SAF

</li>

<li> {@link android.content.Intent#ACTION_OPEN_DOCUMENT}  {@link android.content.Intent#ACTION_CREATE_DOCUMENT}
&mdash; MIME

</li>

<li>
</li>

<li>
 2 Google Drive USB
</li>
</ul>

<p> 3 Google Drive
</p>

<p><img src="{@docRoot}images/providers/storage_picker.png" width="340" alt="picker" style="border:2px solid #ddd" /></p>

<p class="img-caption"><strong> 3.</strong> </p>

<p> Google Drive  4


<p><img src="{@docRoot}images/providers/storage_photos.png" width="340" alt="picker" style="border:2px solid #ddd" /></p>

<p class="img-caption"><strong> 4.</strong></p>

<h2 id="client"> </h2>

<p>Android 4.3 {@link android.content.Intent#ACTION_PICK}  {@link android.content.Intent#ACTION_GET_CONTENT}

 1

 </p>

<p>Android 4.4 {@link android.content.Intent#ACTION_OPEN_DOCUMENT}  UI


 1  UI
</p>

<p>{@link android.content.Intent#ACTION_OPEN_DOCUMENT} {@link android.content.Intent#ACTION_GET_CONTENT}

</p>

<ul>
<li>{@link android.content.Intent#ACTION_GET_CONTENT}

</li>

<li> {@link android.content.Intent#ACTION_OPEN_DOCUMENT}


 </li>

</ul>


<p>{@link android.content.Intent#ACTION_OPEN_DOCUMENT}  {@link android.content.Intent#ACTION_CREATE_DOCUMENT}

</p>


<h3 id="search"></h3>

<p>
 {@link android.content.Intent#ACTION_OPEN_DOCUMENT}

</p>

<pre>private static final int READ_REQUEST_CODE = 42;
...
/**
 * Fires an intent to spin up the &quot;file chooser&quot; UI and select an image.
 */
public void performFileSearch() {

    // ACTION_OPEN_DOCUMENT is the intent to choose a file via the system's file
    // browser.
    Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);

    // Filter to only show results that can be &quot;opened&quot;, such as a
    // file (as opposed to a list of contacts or timezones)
    intent.addCategory(Intent.CATEGORY_OPENABLE);

    // Filter to show only images, using the image MIME data type.
    // If one wanted to search for ogg vorbis files, the type would be &quot;audio/ogg&quot;.
    // To search for all documents available via installed storage providers,
    // it would be &quot;*/*&quot;.
    intent.setType(&quot;image/*&quot;);

    startActivityForResult(intent, READ_REQUEST_CODE);
}</pre>

<p>: </p>
<ul>
<li> {@link android.content.Intent#ACTION_OPEN_DOCUMENT}
</li>

<li> {@link android.content.Intent#CATEGORY_OPENABLE}
</li>

<li>{@code intent.setType("image/*")}  MIME
</li>
</ul>

<h3 id="results"></h3>

<p>{@link android.app.Activity#onActivityResult onActivityResult()}  URI  {@code resultData}


{@link android.content.Intent#getData getData()}  URI URI  URI

</p>

<pre>&#64;Override
public void onActivityResult(int requestCode, int resultCode,
        Intent resultData) {

    // The ACTION_OPEN_DOCUMENT intent was sent with the request code
    // READ_REQUEST_CODE. If the request code seen here doesn't match, it's the
    // response to some other intent, and the code below shouldn't run at all.

    if (requestCode == READ_REQUEST_CODE && resultCode == Activity.RESULT_OK) {
        // The document selected by the user won't be returned in the intent.
        // Instead, a URI to that document will be contained in the return intent
        // provided to this method as a parameter.
        // Pull that URI using resultData.getData().
        Uri uri = null;
        if (resultData != null) {
            uri = resultData.getData();
            Log.i(TAG, "Uri: " + uri.toString());
            showImage(uri);
        }
    }
}
</pre>

<h3 id="metadata"> </h3>

<p>URI URI
</p>

<pre>public void dumpImageMetaData(Uri uri) {

    // The query, since it only applies to a single document, will only return
    // one row. There's no need to filter, sort, or select fields, since we want
    // all fields for one document.
    Cursor cursor = getActivity().getContentResolver()
            .query(uri, null, null, null, null, null);

    try {
    // moveToFirst() returns false if the cursor has 0 rows.  Very handy for
    // &quot;if there's anything to look at, look at it&quot; conditionals.
        if (cursor != null &amp;&amp; cursor.moveToFirst()) {

            // Note it's called &quot;Display Name&quot;.  This is
            // provider-specific, and might not necessarily be the file name.
            String displayName = cursor.getString(
                    cursor.getColumnIndex(OpenableColumns.DISPLAY_NAME));
            Log.i(TAG, &quot;Display Name: &quot; + displayName);

            int sizeIndex = cursor.getColumnIndex(OpenableColumns.SIZE);
            // If the size is unknown, the value stored is null.  But since an
            // int can't be null in Java, the behavior is implementation-specific,
            // which is just a fancy term for &quot;unpredictable&quot;.  So as
            // a rule, check if it's null before assigning to an int.  This will
            // happen often:  The storage API allows for remote files, whose
            // size might not be locally known.
            String size = null;
            if (!cursor.isNull(sizeIndex)) {
                // Technically the column stores an int, but cursor.getString()
                // will do the conversion automatically.
                size = cursor.getString(sizeIndex);
            } else {
                size = &quot;Unknown&quot;;
            }
            Log.i(TAG, &quot;Size: &quot; + size);
        }
    } finally {
        cursor.close();
    }
}
</pre>

<h3 id="open-client"></h3>

<p>URI
</p>

<h4></h4>

<p>{@link android.graphics.Bitmap} </p>

<pre>private Bitmap getBitmapFromUri(Uri uri) throws IOException {
    ParcelFileDescriptor parcelFileDescriptor =
            getContentResolver().openFileDescriptor(uri, "r");
    FileDescriptor fileDescriptor = parcelFileDescriptor.getFileDescriptor();
    Bitmap image = BitmapFactory.decodeFileDescriptor(fileDescriptor);
    parcelFileDescriptor.close();
    return image;
}
</pre>

<p> UI {@link android.os.AsyncTask}
{@link android.widget.ImageView}

</p>

<h4>InputStream </h4>

<p>URI  {@link java.io.InputStream}
</p>

<pre>private String readTextFromUri(Uri uri) throws IOException {
    InputStream inputStream = getContentResolver().openInputStream(uri);
    BufferedReader reader = new BufferedReader(new InputStreamReader(
            inputStream));
    StringBuilder stringBuilder = new StringBuilder();
    String line;
    while ((line = reader.readLine()) != null) {
        stringBuilder.append(line);
    }
    fileInputStream.close();
    parcelFileDescriptor.close();
    return stringBuilder.toString();
}
</pre>

<h3 id="create"></h3>

<p>{@link android.content.Intent#ACTION_CREATE_DOCUMENT}

 MIME
</p>


<pre>
// Here are some examples of how you might call this method.
// The first parameter is the MIME type, and the second parameter is the name
// of the file you are creating:
//
// createFile("text/plain", "foobar.txt");
// createFile("image/png", "mypicture.png");

// Unique request code.
private static final int WRITE_REQUEST_CODE = 43;
...
private void createFile(String mimeType, String fileName) {
    Intent intent = new Intent(Intent.ACTION_CREATE_DOCUMENT);

    // Filter to only show results that can be &quot;opened&quot;, such as
    // a file (as opposed to a list of contacts or timezones).
    intent.addCategory(Intent.CATEGORY_OPENABLE);

    // Create a file with the requested MIME type.
    intent.setType(mimeType);
    intent.putExtra(Intent.EXTRA_TITLE, fileName);
    startActivityForResult(intent, WRITE_REQUEST_CODE);
}
</pre>

<p>{@link android.app.Activity#onActivityResult onActivityResult()}  URI

</p>

<h3 id="delete"></h3>

<p> URI {@link android.provider.DocumentsContract.Document#FLAG_SUPPORTS_DELETE SUPPORTS_DELETE}  {@link android.provider.DocumentsContract.Document#COLUMN_FLAGS Document.COLUMN_FLAGS}


</p>

<pre>
DocumentsContract.deleteDocument(getContentResolver(), uri);
</pre>

<h3 id="edit"></h3>

<p>SAF   {@link android.content.Intent#ACTION_OPEN_DOCUMENT}  {@link android.content.Intent#CATEGORY_OPENABLE}


 </p>

<pre>
private static final int EDIT_REQUEST_CODE = 44;
/**
 * Open a file for writing and append some text to it.
 */
 private void editDocument() {
    // ACTION_OPEN_DOCUMENT is the intent to choose a file via the system's
    // file browser.
    Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);

    // Filter to only show results that can be &quot;opened&quot;, such as a
    // file (as opposed to a list of contacts or timezones).
    intent.addCategory(Intent.CATEGORY_OPENABLE);

    // Filter to show only text files.
    intent.setType(&quot;text/plain&quot;);

    startActivityForResult(intent, EDIT_REQUEST_CODE);
}
</pre>

<p>{@link android.app.Activity#onActivityResult onActivityResult()}<a href="#results"></a> {@link android.content.ContentResolver}  {@link java.io.FileOutputStream}


</p>

<pre>private void alterDocument(Uri uri) {
    try {
        ParcelFileDescriptor pfd = getActivity().getContentResolver().
                openFileDescriptor(uri, "w");
        FileOutputStream fileOutputStream =
                new FileOutputStream(pfd.getFileDescriptor());
        fileOutputStream.write(("Overwritten by MyCloud at " +
                System.currentTimeMillis() + "\n").getBytes());
        // Let the document provider know you're done by closing the stream.
        fileOutputStream.close();
        pfd.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}</pre>

<h3 id="permissions"></h3>

<p> URI
 5


</p>

<p> URI


</p>


<pre>final int takeFlags = intent.getFlags()
            &amp; (Intent.FLAG_GRANT_READ_URI_PERMISSION
            | Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
// Check for the freshest data.
getContentResolver().takePersistableUriPermission(uri, takeFlags);</pre>

<p> 1  URI &mdash;

 {@code getContentResolver().takePersistableUriPermission()}

</p>

<h2 id="custom">  </h2>

<p>
   SAF


</p>


<h3 id="manifest"></h3>

<p>
</p>
<ul>

<li>API  19 </li>

<li>   <code>&lt;provider&gt;</code>
 </li>

<li>: <code>com.example.android.storageprovider.MyCloudProvider</code>
</li>

<li> <code>com.example.android.storageprovider</code> <code>documents</code>

{@code com.example.android.storageprovider.documents} </li>

<li><code>&quot;true&quot;</code>  <code>android:exported</code>
</li>

<li><code>&quot;true&quot;</code>  <code>android:grantUriPermissions</code>

<a href="#permissions"></a>
</li>

<li>{@code MANAGE_DOCUMENTS}

</li>

<li>  {@code android:enabled}
Android 4.3 {@code android:enabled="@bool/atLeastKitKat"}


<ul>
<li>{@code res/values/}  {@code bool.xml}
 <pre>&lt;bool name=&quot;atLeastKitKat&quot;&gt;false&lt;/bool&gt;</pre></li>

<li>{@code res/values-v19/}  {@code bool.xml}
 <pre>&lt;bool name=&quot;atLeastKitKat&quot;&gt;true&lt;/bool&gt;</pre></li>
</ul></li>

<li>{@code android.content.action.DOCUMENTS_PROVIDER}

</li>

</ul>
<p> </p>

<pre>&lt;manifest... &gt;
    ...
    &lt;uses-sdk
        android:minSdkVersion=&quot;19&quot;
        android:targetSdkVersion=&quot;19&quot; /&gt;
        ....
        &lt;provider
            android:name=&quot;com.example.android.storageprovider.MyCloudProvider&quot;
            android:authorities=&quot;com.example.android.storageprovider.documents&quot;
            android:grantUriPermissions=&quot;true&quot;
            android:exported=&quot;true&quot;
            android:permission=&quot;android.permission.MANAGE_DOCUMENTS&quot;
            android:enabled=&quot;&#64;bool/atLeastKitKat&quot;&gt;
            &lt;intent-filter&gt;
                &lt;action android:name=&quot;android.content.action.DOCUMENTS_PROVIDER&quot; /&gt;
            &lt;/intent-filter&gt;
        &lt;/provider&gt;
    &lt;/application&gt;

&lt;/manifest&gt;</pre>

<h4 id="43">Android 4.3 </h4>

<p>{@link android.content.Intent#ACTION_OPEN_DOCUMENT} Android 4.4 Android 4.3  {@link android.content.Intent#ACTION_GET_CONTENT} Android 4.4  {@link android.content.Intent#ACTION_GET_CONTENT}


  {@link android.content.Intent#ACTION_GET_CONTENT}

  UI  2  2

</p>

<p>Android  4.4  {@link android.content.Intent#ACTION_GET_CONTENT}

</p>

<ol>
<li>{@code res/values/}  {@code bool.xml}
 <pre>&lt;bool name=&quot;atMostJellyBeanMR2&quot;&gt;true&lt;/bool&gt;</pre></li>

<li>{@code res/values-v19/}  {@code bool.xml}
 <pre>&lt;bool name=&quot;atMostJellyBeanMR2&quot;&gt;false&lt;/bool&gt;</pre></li>

<li>4.4 API  19 {@link android.content.Intent#ACTION_GET_CONTENT}  <a href="{@docRoot}guide/topics/manifest/activity-alias-element.html"> </a>


<pre>
&lt;!-- This activity alias is added so that GET_CONTENT intent-filter
     can be disabled for builds on API level 19 and higher. --&gt;
&lt;activity-alias android:name=&quot;com.android.example.app.MyPicker&quot;
        android:targetActivity=&quot;com.android.example.app.MyActivity&quot;
        ...
        android:enabled=&quot;@bool/atMostJellyBeanMR2&quot;&gt;
    &lt;intent-filter&gt;
        &lt;action android:name=&quot;android.intent.action.GET_CONTENT&quot; /&gt;
        &lt;category android:name=&quot;android.intent.category.OPENABLE&quot; /&gt;
        &lt;category android:name=&quot;android.intent.category.DEFAULT&quot; /&gt;
        &lt;data android:mimeType=&quot;image/*&quot; /&gt;
        &lt;data android:mimeType=&quot;video/*&quot; /&gt;
    &lt;/intent-filter&gt;
&lt;/activity-alias&gt;
</pre>
</li>
</ol>
<h3 id="contract"></h3>

<p>  <a href="{@docRoot}guide/topics/providers/content-provider-creating.html#ContractClass"> </a>


  {@code public final} URIMIME

  SAF

</p>

<ul>
   <li>{@link android.provider.DocumentsContract.Document}</li>
   <li>{@link android.provider.DocumentsContract.Root}</li>
</ul>

<p>
</p>

<pre>private static final String[] DEFAULT_ROOT_PROJECTION =
        new String[]{Root.COLUMN_ROOT_ID, Root.COLUMN_MIME_TYPES,
        Root.COLUMN_FLAGS, Root.COLUMN_ICON, Root.COLUMN_TITLE,
        Root.COLUMN_SUMMARY, Root.COLUMN_DOCUMENT_ID,
        Root.COLUMN_AVAILABLE_BYTES,};
private static final String[] DEFAULT_DOCUMENT_PROJECTION = new
        String[]{Document.COLUMN_DOCUMENT_ID, Document.COLUMN_MIME_TYPE,
        Document.COLUMN_DISPLAY_NAME, Document.COLUMN_LAST_MODIFIED,
        Document.COLUMN_FLAGS, Document.COLUMN_SIZE,};
</pre>

<h3 id="subclass"> DocumentsProvider</h3>

<p>   {@link android.provider.DocumentsProvider}

</p>

<ul>
<li>{@link android.provider.DocumentsProvider#queryRoots queryRoots()}</li>

<li>{@link android.provider.DocumentsProvider#queryChildDocuments queryChildDocuments()}</li>

<li>{@link android.provider.DocumentsProvider#queryDocument queryDocument()}</li>

<li>{@link android.provider.DocumentsProvider#openDocument openDocument()}</li>
</ul>

<p>
{@link android.provider.DocumentsProvider}
</p>

<h4 id="queryRoots">queryRoots </h4>

<p>{@link android.provider.DocumentsProvider#queryRoots
queryRoots()} {@link android.provider.DocumentsContract.Root}    {@link android.database.Cursor}

</p>

<p> {@code projection}
 1 &mdash;[]  [] 1  1

 1  1
 2
</p>

<pre>
&#64;Override
public Cursor queryRoots(String[] projection) throws FileNotFoundException {

    // Create a cursor with either the requested fields, or the default
    // projection if "projection" is null.
    final MatrixCursor result =
            new MatrixCursor(resolveRootProjection(projection));

    // If user is not logged in, return an empty root cursor.  This removes our
    // provider from the list entirely.
    if (!isUserLoggedIn()) {
        return result;
    }

    // It's possible to have multiple roots (e.g. for multiple accounts in the
    // same app) -- just add multiple cursor rows.
    // Construct one row for a root called &quot;MyCloud&quot;.
    final MatrixCursor.RowBuilder row = result.newRow();
    row.add(Root.COLUMN_ROOT_ID, ROOT);
    row.add(Root.COLUMN_SUMMARY, getContext().getString(R.string.root_summary));

    // FLAG_SUPPORTS_CREATE means at least one directory under the root supports
    // creating documents. FLAG_SUPPORTS_RECENTS means your application's most
    // recently used documents will show up in the &quot;Recents&quot; category.
    // FLAG_SUPPORTS_SEARCH allows users to search all documents the application
    // shares.
    row.add(Root.COLUMN_FLAGS, Root.FLAG_SUPPORTS_CREATE |
            Root.FLAG_SUPPORTS_RECENTS |
            Root.FLAG_SUPPORTS_SEARCH);

    // COLUMN_TITLE is the root title (e.g. Gallery, Drive).
    row.add(Root.COLUMN_TITLE, getContext().getString(R.string.title));

    // This document id cannot change once it's shared.
    row.add(Root.COLUMN_DOCUMENT_ID, getDocIdForFile(mBaseDir));

    // The child MIME types are used to filter the roots and only present to the
    //  user roots that contain the desired type somewhere in their file hierarchy.
    row.add(Root.COLUMN_MIME_TYPES, getChildMimeTypes(mBaseDir));
    row.add(Root.COLUMN_AVAILABLE_BYTES, mBaseDir.getFreeSpace());
    row.add(Root.COLUMN_ICON, R.drawable.ic_launcher);

    return result;
}</pre>

<h4 id="queryChildDocuments">queryChildDocuments </h4>

<p>{@link android.provider.DocumentsProvider#queryChildDocuments queryChildDocuments()} {@link android.provider.DocumentsContract.Document}  {@link android.database.Cursor}


</p>

<p> UI

&mdash;


</p>

<pre>&#64;Override
public Cursor queryChildDocuments(String parentDocumentId, String[] projection,
                              String sortOrder) throws FileNotFoundException {

    final MatrixCursor result = new
            MatrixCursor(resolveDocumentProjection(projection));
    final File parent = getFileForDocId(parentDocumentId);
    for (File file : parent.listFiles()) {
        // Adds the file's display name, MIME type, size, and so on.
        includeFile(result, null, file);
    }
    return result;
}
</pre>

<h4 id="queryDocument">queryDocument </h4>

<p>{@link android.provider.DocumentsProvider#queryDocument queryDocument()} {@link android.provider.DocumentsContract.Document}  {@link android.database.Cursor}


</p>

<p>{@link android.provider.DocumentsProvider#queryDocument queryDocument()} {@link android.provider.DocumentsProvider#queryChildDocuments queryChildDocuments()}


</p>


<pre>&#64;Override
public Cursor queryDocument(String documentId, String[] projection) throws
        FileNotFoundException {

    // Create a cursor with the requested projection, or the default projection.
    final MatrixCursor result = new
            MatrixCursor(resolveDocumentProjection(projection));
    includeFile(result, documentId, null);
    return result;
}
</pre>

<h4 id="openDocument">openDocument </h4>

<p> {@link android.os.ParcelFileDescriptor} {@link android.provider.DocumentsProvider#openDocument
openDocument()}
 {@link android.os.ParcelFileDescriptor}
  {@link android.content.ContentResolver#openFileDescriptor openFileDescriptor()}


</p>

<pre>&#64;Override
public ParcelFileDescriptor openDocument(final String documentId,
                                         final String mode,
                                         CancellationSignal signal) throws
        FileNotFoundException {
    Log.v(TAG, &quot;openDocument, mode: &quot; + mode);
    // It's OK to do network operations in this method to download the document,
    // as long as you periodically check the CancellationSignal. If you have an
    // extremely large file to transfer from the network, a better solution may
    // be pipes or sockets (see ParcelFileDescriptor for helper methods).

    final File file = getFileForDocId(documentId);

    final boolean isWrite = (mode.indexOf('w') != -1);
    if(isWrite) {
        // Attach a close listener if the document is opened in write mode.
        try {
            Handler handler = new Handler(getContext().getMainLooper());
            return ParcelFileDescriptor.open(file, accessMode, handler,
                        new ParcelFileDescriptor.OnCloseListener() {
                &#64;Override
                public void onClose(IOException e) {

                    // Update the file with the cloud server. The client is done
                    // writing.
                    Log.i(TAG, &quot;A file with id &quot; +
                    documentId + &quot; has been closed!
                    Time to &quot; +
                    &quot;update the server.&quot;);
                }

            });
        } catch (IOException e) {
            throw new FileNotFoundException(&quot;Failed to open document with id &quot;
            + documentId + &quot; and mode &quot; + mode);
        }
    } else {
        return ParcelFileDescriptor.open(file, accessMode);
    }
}
</pre>

<h3 id="security"></h3>

<p>

{@link android.provider.DocumentsProvider#queryRoots
queryRoots()}
</p>

<pre>
public Cursor queryRoots(String[] projection) throws FileNotFoundException {
...
    // If user is not logged in, return an empty root cursor.  This removes our
    // provider from the list entirely.
    if (!isUserLoggedIn()) {
        return result;
}
</pre>

<p> {@code getContentResolver().notifyChange()} {@link android.provider.DocumentsContract}
 URI

{@link android.provider.DocumentsProvider#queryRoots queryRoots()}


</p>

<pre>private void onLoginButtonClick() {
    loginOrLogout();
    getContentResolver().notifyChange(DocumentsContract
            .buildRootsUri(AUTHORITY), null);
}
</pre>