Question

首先：我已经对SO上的许多问题进行了筛选，但仍未能得出正确的答案。

以下是我的代码的（简化方式）版本：

private static UriMatcher
        uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);

private static final int
        HOMEWORK_TABLE_REQUEST = 1,
        CLASS_TABLE_REQUEST = 2,
        SETTINGS_TABLE_REQUEST = 3,
        HOMEWORK_ITEM_REQUEST = 4,
        CLASS_ITEM_REQUEST = 5,
        SETTINGS_ITEM_REQUEST = 6;

static {
    uriMatcher.addURI("org.dvc.homeworkReminder.homeworkProvider", "homework", HOMEWORK_TABLE_REQUEST);
    uriMatcher.addURI("org.dvc.homeworkreminder.homeworkProvider", "homework/#", HOMEWORK_ITEM_REQUEST);
    uriMatcher.addURI("org.dvc.homeworkReminder.homeworkProvider", "class", CLASS_TABLE_REQUEST);
    uriMatcher.addURI("org.dvc.homeworkreminder.homeworkProvider", "class/#", CLASS_ITEM_REQUEST);
    uriMatcher.addURI("org.dvc.homeworkReminder.homeworkProvider", "settings", SETTINGS_TABLE_REQUEST);
    uriMatcher.addURI("org.dvc.homeworkreminder.homeworkProvider", "settings/#", SETTINGS_ITEM_REQUEST);
}

这是我的查询方法：

@Override
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
    Cursor cursor = null;   
    Log.i("dfg", "Query method called");
    Log.i("dfg", "Uri = " + uri.toString());
    Log.i("dfg", "Match: " + uriMatcher.match(uri));
    switch(uriMatcher.match(uri)) {
        case HOMEWORK_ITEM_REQUEST:
            Log.i("dfg", "HOMEWORK_ITEM_REQUEST");
            cursor = database.readCursorById(Integer.parseInt(uri.getLastPathSegment()));
            break;
        case HOMEWORK_TABLE_REQUEST:
            Log.i("dfg", "HOMEWORK_TABLE_REQUEST");
            cursor = database.readAllHomework();
            break;
        case CLASS_ITEM_REQUEST:
        case CLASS_TABLE_REQUEST:
        case SETTINGS_ITEM_REQUEST:
        case SETTINGS_TABLE_REQUEST:
            cursor = null;
            break;
        default:
            cursor = null;
            break;
    }
    return cursor;
}

我的类请求或设置请求没有实现，这就是为什么我只是默认返回null。发生了什么事情是我的switch语句一直到default:，并且在我的代码中导致NPE的丰富。您会注意到我的代码中有5个Log语句。以下内容将打印到LogCat。（为什么它仍称为logcat？）

Query method called
Uri = content://org.dvc.homeworkReminder.homeworkProvider/homework/24
Match: -1

现在测试的uri应该与我添加的第二种模式匹配，对吗？我还读到了Uri.parse()方法如何在另一个线程上使用UriMatcher的通配符混淆，所以我使用以下代码构建上面打印的Uri：

Uri returnUri = new Uri.Builder().scheme(ContentResolver.SCHEME_CONTENT).authority("org.dvc.homeworkReminder.homeworkProvider").appendPath("homework").appendPath(String.valueOf(id)).build();

id变量取决于其他一些不太相关的东西。

我的问题是为什么UriMatcher无法正常工作，我将如何修复它？

修正：

我在以下几行中的大小写不正确：

uriMatcher.addURI("org.dvc.homeworkreminder.homeworkProvider", "homework/#", HOMEWORK_ITEM_REQUEST);
uriMatcher.addURI("org.dvc.homeworkreminder.homeworkProvider", "class/#", CLASS_ITEM_REQUEST);
uriMatcher.addURI("org.dvc.homeworkreminder.homeworkProvider", "settings/#", SETTINGS_ITEM_REQUEST);

请注意r中的小写homeworkreminder。感谢布鲁斯发现它！

Answer 1

您正在使用小写提醒＆＃39;当您设置匹配器时，实际的URI具有大写＆＃39;提醒＆＃39;。

UriMatcher不正确匹配

修正：

1 个答案: