Android-Launcher开发之AppWidget(2)

AppWidget 通过内存共享进行数据通讯.原理图如下:

1.创建一个BroadcastReceiver,继承AppWidgetProvider.

2.在AndroidManifest.xml中配置如下:下面给出官网例子<action />是必须的.

    <receiver android:name="ExampleAppWidgetProvider" >
    <intent-filter>
        <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
    </intent-filter>
    <meta-data android:name="android.appwidget.provider"
               android:resource="@xml/example_appwidget_info" />
</receiver>

3.提供一个<meta-data />标签里resource的xml文件,定义appwidget的样式属性(配置参数可选)

<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
    android:minWidth="294dp"
    android:minHeight="72dp"
    android:updatePeriodMillis="86400000"
    android:previewImage="@drawable/preview"
    android:initialLayout="@layout/example_appwidget"
    android:configure="com.example.android.ExampleAppWidgetConfigure" 
    android:resizeMode="horizontal|vertical"
    android:widgetCategory="home_screen|keyguard"
    android:initialKeyguardLayout="@layout/example_keyguard">
</appwidget-provider>

5.当用户点击选取添加某个小部件.首先获取appWidgetId,并打开一个选取小部件的Activity

6.选取后,通过appWidgetId获取appWidgetInfo,并转化为LauncherAppWidgetInfo对象,并添加到workspace中.

当然,这段时间包括了appwidget的定位.其添加源码如下:

 private void completeAddAppWidget(Intent data, CellLayout.CellInfo cellInfo) {
        Bundle extras = data.getExtras();
        int appWidgetId = extras.getInt(AppWidgetManager.EXTRA_APPWIDGET_ID, -1);

        if (LOGD) Log.d(TAG, "dumping extras content=" + extras.toString());

        AppWidgetProviderInfo appWidgetInfo = mAppWidgetManager.getAppWidgetInfo(appWidgetId);

        // Calculate the grid spans needed to fit this widget
        CellLayout layout = (CellLayout) mWorkspace.getChildAt(cellInfo.screen);
        int[] spans = layout.rectToCell(appWidgetInfo.minWidth, appWidgetInfo.minHeight);

        // Try finding open space on Launcher screen
        final int[] xy = mCellCoordinates;
        if (!findSlot(cellInfo, xy, spans[0], spans[1])) {
            if (appWidgetId != -1) mAppWidgetHost.deleteAppWidgetId(appWidgetId);
            return;
        }

        // Build Launcher-specific widget info and save to database
        LauncherAppWidgetInfo launcherInfo = new LauncherAppWidgetInfo(appWidgetId);
        launcherInfo.spanX = spans[0];
        launcherInfo.spanY = spans[1];

        LauncherModel.addItemToDatabase(this, launcherInfo,
                LauncherSettings.Favorites.CONTAINER_DESKTOP,
                mWorkspace.getCurrentScreen(), xy[0], xy[1], false);

        if (!mRestoring) {
            mDesktopItems.add(launcherInfo);

            // Perform actual inflation because we're live
            launcherInfo.hostView = mAppWidgetHost.createView(this, appWidgetId, appWidgetInfo);

            launcherInfo.hostView.setAppWidget(appWidgetId, appWidgetInfo);
            launcherInfo.hostView.setTag(launcherInfo);

            mWorkspace.addInCurrentScreen(launcherInfo.hostView, xy[0], xy[1],
                    launcherInfo.spanX, launcherInfo.spanY, isWorkspaceLocked());
        }
    }

--更新AppWidget界面,其原理如下:

1AppWidgetManager发送广播传递ID.

void updateProvidersForPackageLocked(String pkgName) {
        HashSet<String> keep = new HashSet<String>();
        Intent intent = new Intent(AppWidgetManager.ACTION_APPWIDGET_UPDATE);
        intent.setPackage(pkgName);
        List<ResolveInfo> broadcastReceivers = mPackageManager.queryBroadcastReceivers(intent,
                PackageManager.GET_META_DATA);

        // add the missing ones and collect which ones to keep
        int N = broadcastReceivers == null ? 0 : broadcastReceivers.size();
        for (int i=0; i<N; i++) {
            ResolveInfo ri = broadcastReceivers.get(i);
            ActivityInfo ai = ri.activityInfo;
            if ((ai.applicationInfo.flags & ApplicationInfo.FLAG_EXTERNAL_STORAGE) != 0) {
                continue;
            }
            if (pkgName.equals(ai.packageName)) {
                ComponentName component = new ComponentName(ai.packageName, ai.name);
                Provider p = lookupProviderLocked(component);
                if (p == null) {
                    if (addProviderLocked(ri)) {
                        keep.add(ai.name);
                    }
                } else {
                    Provider parsed = parseProviderInfoXml(component, ri);
                    if (parsed != null) {
                        keep.add(ai.name);
                        // Use the new AppWidgetProviderInfo.
                        p.info = parsed.info;
                        // If it's enabled
                        final int M = p.instances.size();
                        if (M > 0) {
                            int[] appWidgetIds = getAppWidgetIds(p);
                            // Reschedule for the new updatePeriodMillis (don't worry about handling
                            // it specially if updatePeriodMillis didn't change because we just sent
                            // an update, and the next one will be updatePeriodMillis from now).
                            cancelBroadcasts(p);
                            registerForBroadcastsLocked(p, appWidgetIds);
                            // If it's currently showing, call back with the new AppWidgetProviderInfo.
                            for (int j=0; j<M; j++) {
                                AppWidgetId id = p.instances.get(j);
                                id.views = null;
                                if (id.host != null && id.host.callbacks != null) {
                                    try {
                                        id.host.callbacks.providerChanged(id.appWidgetId, p.info);
                                    } catch (RemoteException ex) {
                                        // It failed; remove the callback. No need to prune because
                                        // we know that this host is still referenced by this
                                        // instance.
                                        id.host.callbacks = null;
                                    }
                                }
                            }
                            // Now that we've told the host, push out an update.
                            sendUpdateIntentLocked(p, appWidgetIds);
                        }
                    }
                }
            }
        }

        // prune the ones we don't want to keep
        N = mInstalledProviders.size();
        for (int i=N-1; i>=0; i--) {
            Provider p = mInstalledProviders.get(i);
            if (pkgName.equals(p.info.provider.getPackageName())
                    && !keep.contains(p.info.provider.getClassName())) {
                removeProviderLocked(i, p);
            }
        }
    }

2.用户自定义AppwidgetProvider的onUpdate()接收数据.并通过Manager更新界面.(如下,官网给出了2个操作,1更新界面 2.点击小部件操作)

public class ExampleAppWidgetProvider extends AppWidgetProvider {

    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
        final int N = appWidgetIds.length;

        // Perform this loop procedure for each App Widget that belongs to this provider
        for (int i=0; i<N; i++) {
            int appWidgetId = appWidgetIds[i];

            // Create an Intent to launch ExampleActivity
            Intent intent = new Intent(context, ExampleActivity.class);
            PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, intent, 0);

            // Get the layout for the App Widget and attach an on-click listener
            // to the button
            RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.appwidget_provider_layout);
            views.setOnClickPendingIntent(R.id.button, pendingIntent);

            // Tell the AppWidgetManager to perform an update on the current app widget
            appWidgetManager.updateAppWidget(appWidgetId, views);
        }
    }
}

--Updating the App Widget from the configuration Activity(通过配置选项更改APPwidget界面,当Appwidget创建时,先进入该Activity进行判断)

1.创建Activity并在AndroidManifest.xml里面配置:

         <activity android:name="org.lean.ConfigureActivity" >
            <intent-filter>
                <action android:name="android.appwidget.action.APPWIDGET_CONFIGURE" />
            </intent-filter>
        </activity>

android:configure="org.lean.ConfigureActivity"

package org.lean;

import android.app.Activity;
import android.appwidget.AppWidgetManager;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.EditText;
import android.widget.RemoteViews;

/**
 *		
 *
 * 	@author Lean  @date:2014-8-27  
 */
public class ConfigureActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.configure_view);
		findViewById(R.id.button1).setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				int appwidgetId=getIntent().getExtras().getInt(AppWidgetManager.EXTRA_APPWIDGET_ID,AppWidgetManager.INVALID_APPWIDGET_ID);
				if (appwidgetId!=AppWidgetManager.INVALID_APPWIDGET_ID) {
					//修改远程界面
					EditText editText=(EditText) findViewById(R.id.editText1);
					String currenEtStr=editText.getText().toString();
					RemoteViews views=new RemoteViews(ConfigureActivity.this.getPackageName(),
							R.layout.layout_widget);
					views.setTextViewText(R.id.btn,currenEtStr);
					AppWidgetManager manager=AppWidgetManager.getInstance(ConfigureActivity.this);
					manager.updateAppWidget(appwidgetId, views);
					//返回activity
					
					Intent reIntent=new Intent();
					reIntent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID,appwidgetId);
					setResult(RESULT_OK,reIntent);
					finish();
				}
				
			}
		});
	}
	
}