android - SimpleCursorAdapter 的旧构造函数已弃用……真的吗？

Question

Here它表示 SimpleCursorAdapter 的 API 级别 1 构造函数已弃用，建议使用 LoaderManager 和 CursorLoader。

但是深入研究 LoaderManager 和 CursorLoader 的使用我发现了 this例如，在扩展 ListFragment(我想是 Fragment 本身的扩展)的内部类中，我们创建了一个 CursorLoader。一切似乎都正常，除了 CursorLoader 将 Uri 作为参数这一事实。所以这意味着我需要创建一个 ContentProvider 来访问我的数据库。

我必须承认，为了创建一个包含来自数据库的项目的简单 ListView，必须经历所有这些看起来有点矫枉过正。特别是如果我无意将我的数据库数据提供给其他应用程序，而内容提供商的主要目的就是这样做。

那么它真的值得吗？

特别是在像我这样的情况下，要获取的内容可能会很小。我正在认真考虑以旧方式进行，您怎么看？

Answer 1

我写了一个simple CursorLoader不需要内容提供者:

import android.content.Context;
import android.database.Cursor;
import android.support.v4.content.AsyncTaskLoader;

/**
 * Used to write apps that run on platforms prior to Android 3.0. When running
 * on Android 3.0 or above, this implementation is still used; it does not try
 * to switch to the framework's implementation. See the framework SDK
 * documentation for a class overview.
 *
 * This was based on the CursorLoader class
 */
public abstract class SimpleCursorLoader extends AsyncTaskLoader<Cursor> {
    private Cursor mCursor;

    public SimpleCursorLoader(Context context) {
        super(context);
    }

    /* Runs on a worker thread */
    @Override
    public abstract Cursor loadInBackground();

    /* Runs on the UI thread */
    @Override
    public void deliverResult(Cursor cursor) {
        if (isReset()) {
            // An async query came in while the loader is stopped
            if (cursor != null) {
                cursor.close();
            }
            return;
        }
        Cursor oldCursor = mCursor;
        mCursor = cursor;

        if (isStarted()) {
            super.deliverResult(cursor);
        }

        if (oldCursor != null && oldCursor != cursor && !oldCursor.isClosed()) {
            oldCursor.close();
        }
    }

    /**
     * Starts an asynchronous load of the contacts list data. When the result is ready the callbacks
     * will be called on the UI thread. If a previous load has been completed and is still valid
     * the result may be passed to the callbacks immediately.
     * <p/>
     * Must be called from the UI thread
     */
    @Override
    protected void onStartLoading() {
        if (mCursor != null) {
            deliverResult(mCursor);
        }
        if (takeContentChanged() || mCursor == null) {
            forceLoad();
        }
    }

    /**
     * Must be called from the UI thread
     */
    @Override
    protected void onStopLoading() {
        // Attempt to cancel the current load task if possible.
        cancelLoad();
    }

    @Override
    public void onCanceled(Cursor cursor) {
        if (cursor != null && !cursor.isClosed()) {
            cursor.close();
        }
    }

    @Override
    protected void onReset() {
        super.onReset();

        // Ensure the loader is stopped
        onStopLoading();

        if (mCursor != null && !mCursor.isClosed()) {
            mCursor.close();
        }
        mCursor = null;
    }
}

它只需要 AsyncTaskLoader 类。 Android 3.0以上版本，或者兼容包自带的。