Android11正式版已經(jīng)推出，我們將targetSdkVersion和compileSdkVersion都升級(jí)到30输硝，并升級(jí)pixel4到Android11，發(fā)現(xiàn)分區(qū)存儲(chǔ)讀取圖片失敗程梦。經(jīng)過(guò)分析点把，發(fā)現(xiàn)問(wèn)題如下：

context.contentResolver.query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI
                        , getPhotoProjectionSQL(bucketId)
                        , getMediaSelectionSQL(true, bucketId)
                        , null
                        , getMediaOrderBySQL(start, count + 20))
 
 
private fun getMediaOrderBySQL(start: Int = 0, count: Int = Int.MAX_VALUE) = "${MediaStore.MediaColumns.DATE_MODIFIED} DESC limit $count offset $start"

getMediaOrderBySQL()方法拋出異常：

WechatIMG1.jpeg

從log上看橘荠，是SQL語(yǔ)句出了問(wèn)題，指向limit郎逃。經(jīng)過(guò)各種嘗試哥童，發(fā)現(xiàn)sortOrder這個(gè)參數(shù)在Android11中只支持排序方式，不再支持limit等查詢限制褒翰。但是通常我們加載相冊(cè)圖片/視頻等是需要分頁(yè)的贮懈，從官方文檔中沒(méi)有找到相應(yīng)的例子說(shuō)明。在閱讀query()方法的源碼优训，我們發(fā)現(xiàn)query()的實(shí)現(xiàn)如下：

public final @Nullable Cursor query(@RequiresPermission.Read @NonNull Uri uri,
        @Nullable String[] projection, @Nullable String selection,
        @Nullable String[] selectionArgs, @Nullable String sortOrder,
        @Nullable CancellationSignal cancellationSignal) {
    Bundle queryArgs = createSqlQueryBundle(selection, selectionArgs, sortOrder);
    return query(uri, projection, queryArgs, cancellationSignal);
}

將selection, selectionArgs, sortOrder封裝成一個(gè)Bundle對(duì)象傳給query()方法：

* @param uri The URI, using the content:// scheme, for the content to
 *         retrieve.
 * @param projection A list of which columns to return. Passing null will
 *         return all columns, which is inefficient.
 * @param queryArgs A Bundle containing additional information necessary for
 *            the operation. Arguments may include SQL style arguments, such
 *            as {@link ContentResolver#QUERY_ARG_SQL_LIMIT}, but note that
 *            the documentation for each individual provider will indicate
 *            which arguments they support.
 * @param cancellationSignal A signal to cancel the operation in progress, or null if none.
 * If the operation is canceled, then {@link OperationCanceledException} will be thrown
 * when the query is executed.
 * @return A Cursor object, which is positioned before the first entry. May return
 *         <code>null</code> if the underlying content provider returns <code>null</code>,
 *         or if it crashes.
 * @see Cursor
 */
@Override
public final @Nullable Cursor query(final @RequiresPermission.Read @NonNull Uri uri,
        @Nullable String[] projection, @Nullable Bundle queryArgs,
        @Nullable CancellationSignal cancellationSignal)

不看這段代碼具體的實(shí)現(xiàn)朵你，主要是看注釋對(duì)于queryArgs這個(gè)參數(shù)的說(shuō)明：

 * @param queryArgs A Bundle containing additional information necessary for
 *            the operation. Arguments may include SQL style arguments, such
 *            as {@link ContentResolver#QUERY_ARG_SQL_LIMIT}, but note that
 *            the documentation for each individual provider will indicate
 *            which arguments they support.

such as這句：such as {@link ContentResolver#QUERY_ARG_SQL_LIMIT}，猜測(cè)QUERY_ARG_SQL_LIMIT可能跟我們需要的limit有關(guān)揣非。往回看Bundle的創(chuàng)建過(guò)程：

Bundle queryArgs = createSqlQueryBundle(selection, selectionArgs, sortOrder);
 
public static @Nullable Bundle createSqlQueryBundle(
            @Nullable String selection,
            @Nullable String[] selectionArgs,
            @Nullable String sortOrder) {
 
        if (selection == null && selectionArgs == null && sortOrder == null) {
            return null;
        }
 
        Bundle queryArgs = new Bundle();
        if (selection != null) {
            queryArgs.putString(QUERY_ARG_SQL_SELECTION, selection);
        }
        if (selectionArgs != null) {
            queryArgs.putStringArray(QUERY_ARG_SQL_SELECTION_ARGS, selectionArgs);
        }
        if (sortOrder != null) {
            queryArgs.putString(QUERY_ARG_SQL_SORT_ORDER, sortOrder);
        }
        return queryArgs;
    }

QUERY_ARG_SQL_SELECTION抡医，QUERY_ARG_SQL_SELECTION_ARGS，QUERY_ARG_SQL_SORT_ORDER都是我們的傳參早敬。猜測(cè)是否可以為queryArgs增加QUERY_ARG_SQL_LIMIT來(lái)實(shí)現(xiàn)limit呢忌傻？于是把createSqlQueryBundle()方法copy到我們的代碼中，并增加QUERY_ARG_SQL_LIMIT搁嗓，如下：

val bundle = createSqlQueryBundle(getMediaSelectionSQL(true, bucketId)
                        , null
                        , getMediaOrderBySQLNoLimit(), count + 20, start)
                context.contentResolver.query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI
                        , getPhotoProjectionSQL(bucketId)
                        , bundle
                        , null)
 
 
private fun createSqlQueryBundle(
            selection: String?,
            selectionArgs: Array<String?>?,
            sortOrder: String?, limitCount: Int = 0, offset: Int = 0): Bundle? {
        if (selection == null && selectionArgs == null && sortOrder == null) {
            return null
        }
        val queryArgs = Bundle()
        if (selection != null) {
            queryArgs.putString(ContentResolver.QUERY_ARG_SQL_SELECTION, selection)
        }
        if (selectionArgs != null) {
            queryArgs.putStringArray(ContentResolver.QUERY_ARG_SQL_SELECTION_ARGS, selectionArgs)
        }
        if (sortOrder != null) {
            queryArgs.putString(ContentResolver.QUERY_ARG_SQL_SORT_ORDER, sortOrder)
        }
        queryArgs.putString(ContentResolver.QUERY_ARG_SQL_LIMIT, "$limitCount offset $offset")
        return queryArgs
    }

調(diào)用如下：

val bundle = createSqlQueryBundle(getMediaSelectionSQL(false, bucketId)
                        , null
                        , getMediaOrderBySQLNoLimit(), count + 20, start)
                context.contentResolver.query(MediaStore.Video.Media.EXTERNAL_CONTENT_URI
                        , getVideoProjectionSQL(bucketId)
                        , bundle
                        , null)

經(jīng)測(cè)試分頁(yè)加載成功芯勘。