SimpleCursorAdapter&;的旧构造函数已弃用。真的? [英] SimpleCursorAdapter's old constructor deprecated.. really?
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LoaderManager
和CursorLoader
。
但是深入研究LoaderManager
和CursorLoader
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。
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。
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