[Android Pro] Android异步任务处理之AsyncTaskLoader的使用

/*** Created by Administrator on 2016/5/25.*/
public class AppEntry {private String mLabel;//应用文字标签private Drawable mIcon;//应用图标private final AppListLoader mLoader;private final ApplicationInfo mInfo;//<application>节点信息，只有一个//PackageInfo、ApplicationInfo、ActivityInfo、ResolveInfo四种信息类的一种private final File mApkFile;private boolean mMounted;public AppEntry(AppListLoader mLoader,ApplicationInfo mInfo ) {this.mInfo = mInfo;this.mLoader = mLoader;mApkFile=new File(mInfo.sourceDir);//sourceDir=Full path to the location of this package
    }public ApplicationInfo getApplicationInfo() {return mInfo;}public String getLabel() {return mLabel;}public Drawable getIcon() {if (mIcon == null) {if (mApkFile.exists()) {mIcon = mInfo.loadIcon(mLoader.mPm);//public Drawable loadIcon (PackageManager pm){}获取应用图标return mIcon;} else {mMounted = false;}} else if (!mMounted) {// If the app wasn't mounted but is now mounted, reload its icon.if (mApkFile.exists()) {mMounted = true;mIcon = mInfo.loadIcon(mLoader.mPm);return mIcon;}} else {return mIcon;}return mLoader.getContext().getResources().getDrawable(android.R.drawable.sym_def_app_icon);//否则返回默认的小机器人
    }@Overridepublic String toString() {return mLabel;}void loadLabel(Context context) {if (mLabel == null || !mMounted) {if (!mApkFile.exists()) {mMounted = false;mLabel = mInfo.packageName;//获取程序名称} else {mMounted = true;CharSequence label = mInfo.loadLabel(context.getPackageManager());mLabel = label != null ? label.toString() : mInfo.packageName;}}}
}

public class AppListLoader  extends AsyncTaskLoader<List<AppEntry>> {private static final String TAG = "ADP_AppListLoader";private static final boolean DEBUG = true;final PackageManager mPm;//包管理器private List<AppEntry> mApps;//装在应用程序实体的容器// An observer to notify the Loader when new apps are installed/updated.private InstalledAppsObserver mAppsObserver;//非系统应用程序安装或者卸载的广播接收器// The observer to notify the Loader when the system Locale has been changed.private SystemLocaleObserver mLocaleObserver;//系统应用程序安装或者卸载的广播接收器public AppListLoader(Context context) {super(context);mPm = getContext().getPackageManager();Log.i("TAG","AppListLoader(Context)");}@Overrideprotected void onStartLoading() {Log.i("TAG","onStartLoading()");if(mApps!=null){deliverResult(mApps);}// Register the observers that will notify the Loader when changes are made.if (mAppsObserver == null) {mAppsObserver = new InstalledAppsObserver(this);//注册一个非系统应用程序的接收器
        }if (mLocaleObserver == null) {mLocaleObserver = new SystemLocaleObserver(this);//注册一个系统应用程序的接收器
        }if (takeContentChanged()) {forceLoad();} else if (mApps == null) {forceLoad();//强制加载数据
        }}@Overridepublic void forceLoad() {Log.i("TAG","forceLoad()");super.forceLoad();}@Overridepublic List<AppEntry> loadInBackground() {Log.i("TAG","loadInBackground()");List<ApplicationInfo> apps=mPm.getInstalledApplications(0);
//        public static final int FILTER_ALL_APP = 0; // 所有应用程序  
//        public static final int FILTER_SYSTEM_APP = 1; // 系统程序  
//        public static final int FILTER_THIRD_APP = 2; // 第三方应用程序  
//        public static final int FILTER_SDCARD_APP = 3; // 安装在SDCard的应用程序 if(apps==null){apps=new ArrayList<>();}List<AppEntry> entries=new ArrayList<>(apps.size());//开始加载数据for(int i=0;i<apps.size();i++){AppEntry appEntry=new AppEntry(this,apps.get(i));appEntry.loadLabel(getContext());entries.add(appEntry);}//Sort the listCollections.sort(entries,ALPHA_COMPARATOR);//对应用程序进行排序return entries;}@Overridepublic void deliverResult(List<AppEntry> datas) {//分发loadInBackground（）方法返回的结果Log.i("TAG","deliverResult()");if(isReset()){if(datas!=null){releaseResources(datas);//可以释放相关资源return;}}List<AppEntry> oldApps=mApps;mApps=datas;if(isStarted()){super.deliverResult(datas);}if(oldApps!=null&&oldApps!=datas){releaseResources(oldApps);}}@Overrideprotected void onStopLoading() {//停止加载数据Log.i("TAG","onStopLoading()");cancelLoad();}@Overrideprotected void onReset() {Log.i("TAG","onReset()");onStopLoading();// At this point we can release the resources associated with 'apps'.if (mApps != null) {releaseResources(mApps);mApps = null;}// The Loader is being reset, so we should stop monitoring for changes.if (mAppsObserver != null) {getContext().unregisterReceiver(mAppsObserver);//注销广播接收器mAppsObserver = null;}if (mLocaleObserver != null) {getContext().unregisterReceiver(mLocaleObserver);//注销广播接收器mLocaleObserver = null;}}@Overridepublic void onCanceled(List<AppEntry> apps) {  // Attempt to cancel the current asynchronous load.super.onCanceled(apps);Log.i("TAG","onCanceled()");releaseResources(apps);}/*** Helper method to take care of releasing resources associated with an* actively loaded data set.*/private void releaseResources(List<AppEntry> apps) {// For a simple List, there is nothing to do. For something like a Cursor,// we would close it in this method. All resources associated with the// Loader should be released here.
    }/*** Performs alphabetical comparison of {@link AppEntry} objects. This is* used to sort queried data in {@link }.*/private static final Comparator<AppEntry> ALPHA_COMPARATOR = new Comparator<AppEntry>() {Collator sCollator = Collator.getInstance();@Overridepublic int compare(AppEntry object1, AppEntry object2) {return sCollator.compare(object1.getLabel(), object2.getLabel());}};
}

public class MainActivity extends FragmentActivity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);
//将AppListFragment添加到当前的activity里 FragmentManager fm=getSupportFragmentManager();if(fm.findFragmentById(android.R.id.content)==null){AppListFragment list=new AppListFragment();fm.beginTransaction().add(android.R.id.content,list).commit();}}
//实现LoaderManager.LoaderCallbacks的接口public static class AppListFragment extends ListFragment implements LoaderManager.LoaderCallbacks<List<AppEntry>>{private static final String TAG = "ADP_AppListFragment";private static final boolean DEBUG = true;private AppListAdapter mAdapter;private static final int LOADER_ID = 1;@Overridepublic void onActivityCreated(@Nullable Bundle savedInstanceState) {super.onActivityCreated(savedInstanceState);setHasOptionsMenu(true);mAdapter=new AppListAdapter(getActivity());setEmptyText("No Applications");setListAdapter(mAdapter);setListShown(false);if (getLoaderManager().getLoader(LOADER_ID) == null) {Log.i("TAG", "Initializing the new Loader...");} else {Log.i("TAG", "Reconnecting with existing Loader (id '1')...");}getLoaderManager().initLoader(LOADER_ID, null, this);}@Overridepublic Loader<List<AppEntry>> onCreateLoader(int id, Bundle args) {Log.i("TAG", "onCreateLoader()");return new AppListLoader(getActivity());}@Overridepublic void onLoadFinished(Loader<List<AppEntry>> loader, List<AppEntry> data) {Log.i("TAG", "onLoadFinished()");mAdapter.setData(data);if(isResumed()){setListShown(true);}else {setListShownNoAnimation(true);}}@Overridepublic void onLoaderReset(Loader<List<AppEntry>> loader) {Log.i("TAG", "onLoaderReset()");mAdapter.setData(null);}
}

05-25 12:57:46.050 11184-11184/com.troy.applistloader I/TAG: +++ Calling initLoader()! +++
05-25 12:57:46.050 11184-11184/com.troy.applistloader I/TAG: +++ Initializing the new Loader... +++
05-25 12:57:46.050 11184-11184/com.troy.applistloader I/TAG: onCreateLoader()
05-25 12:57:46.050 11184-11184/com.troy.applistloader I/TAG: onStartLoading()
05-25 12:57:46.060 11184-11184/com.troy.applistloader I/TAG: forceLoad()
05-25 12:57:46.060 11184-13196/com.troy.applistloader I/TAG: loadInBackground()
05-25 12:57:47.530 11184-11184/com.troy.applistloader I/TAG: deliverResult()
05-25 12:57:47.530 11184-11184/com.troy.applistloader I/TAG: onLoadFinished()

05-25 13:00:08.790 11184-11184/com.troy.applistloader I/TAG: onStopLoading()
05-25 13:00:08.790 11184-11184/com.troy.applistloader I/TAG: onLoaderReset()
05-25 13:00:08.790 11184-11184/com.troy.applistloader I/TAG: onReset()
05-25 13:00:08.790 11184-11184/com.troy.applistloader I/TAG: onStopLoading()