Android widget使用

widget必须继承AppWidgetProvider
在AppWidgetProvider源码中可以看到AppWidgetProvider继承了BroadcastReceiver
也就是说widget本身就是个BroadcastReceiver(广播接受者)

AndroidManifest.xml中配置

<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>

当往窗口添加widget是会发出更新广播
更新广播的名称为"android.appwidget.action.APPWIDGET_UPDATE"
meta-data为组件提供参数
android:name="android.appwidget.provider"为固定的
android:resource="@xml/example_appwidget_info"为widght所采用的界面

example_appwidget_info.xml代码

<?xml version="1.0" encoding="utf-8"?><appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"    android:minWidth="294dp"    android:minHeight="72dp"    android:updatePeriodMillis="0"    android:initialLayout="@layout/time_appwidget"></appwidget-provider>

time_appwidget.xml代码

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:orientation="vertical"    android:background="@drawable/rectangle" >    <TextView         android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:id="@+id/textView"    android:textColor="@android:color/black"    android:textSize="20dp"    android:text="Just For Test"/></LinearLayout>

一个简单的wdiget,只有一句话"Just For Test"

接下来改进一下，把文字换成时间

public class TimeWidgetProvider extends AppWidgetProvider {@Overridepublic void onUpdate(Context context, AppWidgetManager appWidgetManager,int[] appWidgetIds) {SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");String time = dateFormat.format(System.currentTimeMillis());RemoteViews remoteView = new RemoteViews(context.getPackageName(), R.layout.time_appwidget);remoteView.setTextViewText(R.id.textView, time);appWidgetManager.updateAppWidget(appWidgetIds[0], remoteView);}}

部署后时间出来了，但是时间是固定的，没有改变，需要加入服务
新建服务

package com.ice.widght;import java.text.SimpleDateFormat;import java.util.Timer;import java.util.TimerTask;import android.app.Service;import android.appwidget.AppWidgetManager;import android.content.ComponentName;import android.content.Intent;import android.os.IBinder;import android.widget.RemoteViews;public class TimeWidgetService extends Service {private Timer timer;@Overridepublic void onCreate() {timer = new Timer();timer.schedule(new TimeUpdateTask(), 0, 1000);}private class TimeUpdateTask extends TimerTask{@Overridepublic void run() {SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");String time = dateFormat.format(System.currentTimeMillis());RemoteViews remoteView = new RemoteViews(getPackageName(), R.layout.time_appwidget);remoteView.setTextViewText(R.id.textView, time);AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(getApplicationContext());appWidgetManager.updateAppWidget(new ComponentName(getApplicationContext(), TimeWidgetProvider.class), remoteView);}}@Overridepublic void onDestroy() {timer.cancel();timer = null;}@Overridepublic IBinder onBind(Intent arg0) {// TODO Auto-generated method stubreturn null;}}

TimeWidgetProvider重构代码，负责开启和销毁服务

public class TimeWidgetProvider extends AppWidgetProvider {@Overridepublic void onEnabled(Context context) {context.startService(new Intent(context, TimeWidgetService.class));}@Overridepublic void onDisabled(Context context) {context.stopService(new Intent(context, TimeWidgetService.class));}}

完工~~~

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