CursorLoader的使用没有ContentProvider

问题描述

限时删除！！

Android SDK文档说， startManagingCursor（）方法被折磨：

c $ c> CursorLoader 。但是当我需要在<$ c $的构造函数中使用URI时，如何使用它与自定义 CursorAdapter 和 ContentProvider c> CursorLoader ？

解决方案

我写了一个不需要内容提供者：

  import android.content.Context; 
 import android.database.Cursor; 
 import android.support.v4.content.AsyncTaskLoader; 
 
 / ** 
 *用于编写在Android 3.0之前的平台上运行的应用程序。当在Android 3.0或更高版本上运行
 *时，此实现仍然使用;它不尝试
 *切换到框架的实现。有关类概述，请参阅框架SDK 
 *文档。 
 * 
 *这是基于CursorLoader类
 * / 
 public abstract class SimpleCursorLoader extends AsyncTaskLoader< Cursor> {
 private Cursor mCursor; 
 
 public SimpleCursorLoader（Context context）{
 super（context）; 
} 
 
 / *在工作线程上运行* / 
 @Override 
 public abstract Cursor loadInBackground（）; 
 
 / *在UI线程上运行* / 
 @Override 
 public void deliverResult（Cursor cursor）{
 if（isReset（））{
 //加载器停止时出现异步查询
 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（）; 
} 
} 
 
 / ** 
 *开始异步加载联系人列表数据。当结果准备好时，回调
 *将在UI线程上被调用。如果先前的加载已经完成并且仍然有效
 *，则结果可以立即传递到回调。 
 *< p /> 
 *必须从UI线程调用
 * / 
 @Override 
 protected void onStartLoading（）{
 if（mCursor！= null）{
 deliverResult（mCursor）; 
} 
 if（takeContentChanged（）|| mCursor == null）{
 forceLoad（）; 
} 
} 
 
 / ** 
 *必须从UI线程调用
 * / 
 @Override 
 protected void onStopLoading（）{
 //如果可能，尝试取消当前加载任务。 
 cancelLoad（）; 
} 
 
 @Override 
 public void onCanceled（Cursor cursor）{
 if（cursor！= null&！amp;！cursor.isClosed（））{
 cursor.close（）; 
} 
} 
 
 @Override 
 protected void onReset（）{
 super.onReset（）; 
 
 //确保加载器已停止
 onStopLoading（）; 
 
 if（mCursor！= null&&！mCursor.isClosed（））{
 mCursor.close（）; 
} 
 mCursor = null; 
} 
} 
  

它只需要 AsyncTaskLoader 类。

我也是，它与 LoadManager 兼容，用于检索通用的 java.util.List 集合。 / p>

Android SDK documentation says that startManagingCursor() method is depracated:

So I would like to use CursorLoader. But how can I use it with custom CursorAdapter and without ContentProvider, when I needs URI in constructor of CursorLoader?

解决方案

I wrote a simple CursorLoader that does not need a content provider:

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;
    }
}

It only needs the AsyncTaskLoader class. Either the one in Android 3.0 or higher, or the one that comes with the compatibility package.

I also wrote a ListLoader which is compatible with the LoadManager and is used to retrieve a generic java.util.List collection.

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