android - 没有ContentProvider的CursorLoader用法

Android SDK文档说startManagingCursor()方法已被弃用：


不建议使用此方法。而是将新的CursorLoader类与LoaderManager一起使用；在旧版平台上，也可以通过Android兼容性软件包获得此功能。此方法使活动可以根据活动的生命周期来为您管理给定的Cursor生命周期。也就是说，当活动停止时，它将自动在给定的Cursor上调用deactivate（），而在稍后重新启动时，它将为您调用requery（）。当活动被销毁时，所有托管游标将自动关闭。如果您的目标是HONEYCOMB或更高版本，请考虑改用LoaderManager（可通过getLoaderManager（）获得）


所以我想使用CursorLoader。但是，当我在CursorAdapter的构造函数中需要URI时，如何与自定义ContentProvider和没有CursorLoader一起使用它？

最佳答案

我写了一个simple CursorLoader，不需要内容提供程序：

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。要么是Android 3.0或更高版本中的一种，要么是兼容软件包随附的一种。

我也wrote a ListLoader与LoadManager兼容，并用于检索通用的java.util.List集合。

关于android - 没有ContentProvider的CursorLoader用法，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/37949810/