AppWidgetProvider的使用

一介紹：

AppWidgetProvider 是Android用於生成桌面小部件的類，它繼承自BroadCastReceiver.所以它本質

上是一個廣播接受者，謹記這一點，AppWidgerProvider的很多功能都好理解了。如圖：

二開發一個桌面小部件的步驟

我會根據一個小demo，來記錄整個桌面的開發流程，先看一下demo的效果（是一個時鐘和文本

用來形象的顯示時間，日期）。

實現具體步驟：

1，定義小部件的界面佈局

定義res/layout/appwidget_clock.xml（文件名可以自定義），根據你的需求編寫佈局（即你希望你的小部件的樣子）。

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageView
        android:id="@+id/id_iv_clock"
        android:layout_width="150dp"
        android:layout_height="150dp"
        android:layout_centerInParent="true"
        android:background="@android:color/transparent"/>

    <TextView
        android:id="@+id/id_tv_clock"
        android:layout_width="150dp"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_below="@+id/id_iv_clock"
        android:textColor="@android:color/white"
        android:background="@android:color/transparent"
        android:gravity="center"
        android:text="02/16 週四 上午 10:30"/>

</RelativeLayout>

2，配置小部件的配置信息

定義res/xml/appwidget_clock（文件名可自定義），添加如下內容

<?xml version="1.0" encoding="utf-8"?>
<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
    android:minHeight="150dp"
    android:minWidth="150dp"
    android:initialLayout="@layout/appwidget_clock"
    android:updatePeriodMillis="0">

</appwidget-provider>

其中minWidth與minHeight定義小部件的寬高，initialLayout初始化佈局文件。updatePeriodMillis更新的週期（0表示沒有更新週期）。

3，定義小部件類，繼承AppWidgetProvider。

/**
 * 
 * 最重要的方法有兩種onReceive, onUpdate.
 * onUpdate, 小部件被加載到桌面
 * onReceive，自定義的點擊事件（即發送自定義的廣播，在這裏接收並處理）。
 */

public class AppWidgetClockProvider extends AppWidgetProvider {

    public static final String tag = "AppWidgetClockProvider";
    private static RemoteViews remoteViews;
    //自定義的廣播Action。
    public static final String AppWidget_Click_Action = "com.example.littledemo.appwidgetclockprovider";
    //自定義的時鐘的Drawable，根據當前的時間，繪製正確的圖形。
    ClockDrawable clockDrawable;
    //用於實現，每隔一秒更新桌面小部件，（最好應該啓動service定時跟新小部件，因爲廣播接收器的生命週期很短）
    Timer timer;
    Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
        }
    };
    
    /**
     * 接收廣播
     * @param context
     * @param intent
     */
    @Override
    public void onReceive(Context context, Intent intent) {
        super.onReceive(context, intent);
        LogUtil.i(tag, "onReceive");
        String action = intent.getAction();
        LogUtil.i(tag, "action" + action);
        //接收到click點擊事件發送的廣播，啓動主界面（響應點擊事件）
        if(AppWidget_Click_Action.equals(action)){
            Intent in = new Intent(context, AppWidgetActivity.class);
            in.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            context.startActivity(in);
        }
    }

    /**
     * 小部件被更新時，調用方法
     * (原以爲響應updatePeriodMillis 定義的週期，但其實沒有。)
     * @param context
     * @param appWidgetManager
     * @param appWidgetIds
     */
    @Override
    public void onUpdate(final Context context, final AppWidgetManager appWidgetManager, final int[] appWidgetIds) {
        super.onUpdate(context, appWidgetManager, appWidgetIds);
        LogUtil.i(tag, "onUpdate");
        //啓動定義任務，更新小部件
        if(timer == null){
            timer = new Timer();
            timer.schedule(new TimerTask() {
                @Override
                public void run() {
                    handler.post(new Runnable() {
                        @Override
                        public void run() {
                            for (int i = 0; i < appWidgetIds.length; i++) {
                                onWidgetUpdate(context, appWidgetManager, appWidgetIds[i]);
                            }
                        }
                    });
                }
            }, 0, 1000);
        }
    }

    private void onWidgetUpdate(Context context, AppWidgetManager appWidgetManager, int appWidgetId){
        RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.appwidget_clock);

        //設置點擊事件
        Intent intent = new Intent(AppWidget_Click_Action);
        PendingIntent pIntent = PendingIntent.getBroadcast(context, 0, intent, 0);
        remoteViews.setOnClickPendingIntent(R.id.id_iv_clock, pIntent);

        //更新小部件，圖標
        if(clockDrawable == null){
            clockDrawable = new ClockDrawable(context);
            clockDrawable.setBounds(0, 0, PixelUtil.dp2px(150, context),PixelUtil.dp2px(150, context));
        }
        Bitmap bitmap = BitmapUtil.drawable2Bitmap(clockDrawable);
        remoteViews.setImageViewBitmap(R.id.id_iv_clock, bitmap);
        //更新部件文本
        String txt = StringUtil.getAppWidgetTxt();
        remoteViews.setTextViewText(R.id.id_tv_clock, txt);

        //更新部件
        appWidgetManager.updateAppWidget(appWidgetId, remoteViews);
        bitmap.recycle();
    }

    /**
     * 每刪除一次窗口小部件，就調用一次
     *
     * @param context
     * @param appWidgetIds
     */
    @Override
    public void onDeleted(Context context, int[] appWidgetIds) {
        super.onDeleted(context, appWidgetIds);
        LogUtil.i(tag, "onDeleted");
        LogUtil.i(tag, "timer is" + timer != null? "timer" : null);
        if(timer != null){
            timer.cancel();
        }
        timer = null;
    }

    /**
     * 當最後一個窗口小部件被刪除時，調用此方法
     *
     * @param context
     */
    @Override
    public void onDisabled(Context context) {
        super.onDisabled(context);
        LogUtil.i(tag, "onDisabled");
    }

    /**
     * 當第一個框口小部件第一次被添加到桌面，調用此方法
     *
     * @param context
     */
    @Override
    public void onEnabled(Context context) {
        super.onEnabled(context);
        LogUtil.i(tag, "onEnabled");
    }

    @Override
    public void onRestored(Context context, int[] oldWidgetIds, int[] newWidgetIds) {
        super.onRestored(context, oldWidgetIds, newWidgetIds);
        LogUtil.i(tag, "onRestored");
    }

    @Override
    public void onAppWidgetOptionsChanged(Context context, AppWidgetManager appWidgetManager, int appWidgetId, Bundle newOptions) {
        super.onAppWidgetOptionsChanged(context, appWidgetManager, appWidgetId, newOptions);
        LogUtil.i(tag, "onAppWidgetOptionsChanged");
    }

}

4，在AndroidMinifest.xml中聲明小部件類

        <receiver android:name=".appwidget.AppWidgetClockProvider">
            <meta-data
                android:name="android.appwidget.provider"
                android:resource="@xml/appwidget_clock">
            </meta-data>

            <intent-filter>
                <action android:name="com.example.littledemo.appwidgetclockprovider"></action>
                <action android:name="android.appwidget.action.APPWIDGET_UPDATE"></action>
                <action android:name="android.appwidget.action.APPWIDGET_UPDATE_OPTIONS"></action>
                <action android:name="android.appwidget.action.APPWIDGET_RESTORED"></action>
                <action android:name="android.appwidget.action.APPWIDGET_DELETED"></action>
            </intent-filter>
        </receiver>

注意，<action android:name="android.appwidget.action.APPWIDGET_UPDATE"></action>是必須添加的

如果不添加，則不發出現在小部件的列表中。其中

<action android:name="com.example.littledemo.appwidgetclockprovider"></action>

是自定義的Action，是小部件上的點擊事件所要發送的廣播Action；

下面附上一個工具的類的代碼：

自定義ClockDrawable：

public class ClockDrawable extends Drawable {

    private Paint mPaint;
    private final static int C_default = Color.WHITE;
    private final static String tag = "ClockDrawable";
    private Context mContext;
    private int padding = 2;

    public ClockDrawable(Context context) {
        this.mContext = context;
        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setColor(C_default);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeWidth(PixelUtil.dp2px(2, mContext));
        mPaint.setTextSize(PixelUtil.sp2px(12, mContext));
        padding = PixelUtil.dp2px(padding, mContext);
    }

    @Override
    public void draw(Canvas canvas) {
        LogUtil.i(tag, "draw");
        final Rect rect = getBounds();
        //畫圓
        drawCircle(rect, canvas);
        //畫豎線
        drawVerLine(rect, canvas);
        //畫數字
        drawNum(rect, canvas);
        //畫時針和分針
        drawHourMinuteHand(rect, canvas);
    }

    private void drawCircle(Rect rect, Canvas canvas) {
        float cx = rect.exactCenterX();
        float cy = rect.exactCenterY();
        float radius = Math.min(cx, cy) - padding;
        canvas.drawCircle(cx, cy, radius, mPaint);
        canvas.drawCircle(cx, cy, PixelUtil.dp2px(2, mContext), mPaint);
    }

    private void drawVerLine(Rect rect, Canvas canvas) {
        float cx = rect.exactCenterX();
        float cy = rect.exactCenterY();
        for (int i = 0; i < 12; i++) {
            canvas.save();
            canvas.rotate(30 * i, cx, cy);
            canvas.drawLine(cx, padding, cx, padding + PixelUtil.dp2px(5, mContext), mPaint);
            canvas.restore();
        }
    }

    private void drawNum(Rect rect, Canvas canvas) {
        float cx = rect.exactCenterX();
        float cy = rect.exactCenterY();
        for (int i = 0; i < 12; i++) {
            canvas.save();

            String txt = "" + i;
            if (i == 0) {
                txt = "12";
            }
            Rect tempRect = new Rect();
            mPaint.getTextBounds(txt, 0, txt.length(), tempRect);

            if (i == 0 || i == 1 || i == 2 || i == 10 || i == 11) {
                canvas.rotate(30 * i, cx, cy);
                float x = cx - tempRect.width() / 2.0f;
                float y = padding + PixelUtil.dp2px(5, mContext) + tempRect.height();
                canvas.drawText(txt, x, y, mPaint);
            } else if (i == 3) {
                float x = rect.width() - padding - tempRect.width() - PixelUtil.dp2px(5, mContext);
                float y = rect.height() / 2.0f + tempRect.height() / 2.0f;
                canvas.drawText(txt, x, y, mPaint);
            } else if (i == 9) {
                float x = padding + PixelUtil.dp2px(5, mContext);
                float y = rect.height() / 2.0f + tempRect.height() / 2.0f;
                canvas.drawText(txt, x, y, mPaint);
            } else {
                canvas.rotate(30 * (i - 6), cx, cy);
                float x = cx - tempRect.width() / 2.0f;
                float y = rect.height() - padding - PixelUtil.dp2px(5, mContext);
                canvas.drawText(txt, x, y, mPaint);
            }
            canvas.restore();
        }
    }

    private void drawHourMinuteHand(Rect rect, Canvas canvas) {
        float cx = rect.exactCenterX();
        float cy = rect.exactCenterY();
        Calendar calendar = Calendar.getInstance();
        int hour = calendar.get(Calendar.HOUR_OF_DAY);
        int minutes = calendar.get(Calendar.MINUTE);
        int second = calendar.get(Calendar.SECOND);

        int rotate = (int) (360f * (hour * 60 * 60 + minutes * 60 + second) / (12 * 60.0f * 60));
        LogUtil.i(tag, "hour:" + hour + " minutes:" + minutes + " second:" + second + " rotate:" + rotate);

        canvas.save();
        canvas.rotate(rotate, cx, cy);
        canvas.drawLine(cx, cy - rect.height() / 6.0f, cx, cy + rect.height() / 10.0f, mPaint);
        canvas.restore();

        canvas.save();
        canvas.rotate(360 * (minutes * 60 + second) / (60 * 60.0f), cx, cy);
        canvas.drawLine(cx, cy - rect.height() / 4.0f, cx, cy + rect.height() / 10.0f, mPaint);
        canvas.restore();
    }

    @Override
    public void setBounds(Rect bounds) {
        super.setBounds(bounds);
    }

    @Override
    public void setAlpha(int alpha) {
        mPaint.setAlpha(alpha);
    }

    @Override
    public void setColorFilter(ColorFilter colorFilter) {
        mPaint.setColorFilter(colorFilter);
    }

    @Override
    public int getOpacity() {
        return PixelFormat.TRANSLUCENT;
    }
}

BItmapUtil

public class BitmapUtil {

    /**
     * 根據Drawaable轉Bitmap
     * @param drawable
     * @return
     */
    public static Bitmap drawable2Bitmap(Drawable drawable){
        Bitmap bitmap = Bitmap.createBitmap(drawable.getBounds().width(), drawable.getBounds().height(), Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);
        drawable.draw(canvas);
        return bitmap;
    }
}

StringUtil

public class StringUtil {

    private static String[] weeks = new String[]{
            "週日", "週一","週二"," 週三","週四","週五","週六"
    };

    public static String getAppWidgetTxt(){
        Calendar calendar = Calendar.getInstance();
        int month = calendar.get(Calendar.MONTH) + 1;
        int day = calendar.get(Calendar.DAY_OF_MONTH);
        int day_of_week = calendar.get(Calendar.DAY_OF_WEEK);
        int am = calendar.get(Calendar.AM_PM);

        StringBuffer sb = new StringBuffer();
        sb.append(month+ "/" + day + " ")
                .append(weeks[day_of_week - 1] + " ")
                .append(am == 0 ? "上午 " : "下午 ")
                .append(SDFUtil.format("hh:mm", calendar.getTimeInMillis()));
        return sb.toString();
    }
}