SimpleCursorAdapter&的旧构造函数已弃用。真的? [英] SimpleCursorAdapter's old constructor deprecated.. really?

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本文介绍了SimpleCursorAdapter&的旧构造函数已弃用。真的?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

问题描述

Here表示SimpleCursorAdapter的API一级构造函数已弃用,建议使用LoaderManagerCursorLoader

但是深入研究LoaderManagerCursorLoader的用法,我发现了this示例,在扩展ListFragment(我认为是片段本身的扩展)的内部类中,我们创建了一个CursorLoader。除了CursorLoader接受Uri作为参数之外,一切似乎都很好。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,仅仅为了用来自数据库的项创建一个简单的ListView就必须经历所有这些,这看起来有点过分。特别是如果我不打算让我的数据库数据对其他应用程序可用,而内容提供商的主要目的就是这样做的话。

那么这真的值得吗?

尤其是在像我这样的情况下,要获取的内容可能很小。我正在认真考虑用老方法来做这件事,你说呢?

推荐答案

我编写了一个不需要内容提供商的simple CursorLoader

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;
    }
}

只需要AsyncTaskLoader类。Android 3.0或更高版本中的版本,或者兼容包附带的版本。

这篇关于SimpleCursorAdapter&amp;的旧构造函数已弃用。真的?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!

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