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 {

	@Override
	public 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;
	
	@Override
	public void onCreate() {
		timer = new Timer();
		timer.schedule(new TimeUpdateTask(), 0, 1000);
	}
	
	private class TimeUpdateTask extends TimerTask{
		@Override
		public 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);
		}
	}

	@Override
	public void onDestroy() {
		timer.cancel();
		timer = null;
	}

	@Override
	public IBinder onBind(Intent arg0) {
		// TODO Auto-generated method stub
		return null;
	}

}

TimeWidgetProvider重构代码，负责开启和销毁服务

public class TimeWidgetProvider extends AppWidgetProvider {

	@Override
	public void onEnabled(Context context) {
		context.startService(new Intent(context, TimeWidgetService.class));
	}

	@Override
	public void onDisabled(Context context) {
		context.stopService(new Intent(context, TimeWidgetService.class));
	}

}

完工~~~