改写，原文地址：http://blog.csdn.net/android_tutor/article/details/5544471
Widget就是Android中的一个挂件。曾几何时，这个被认为是革命性的东西，现在慢慢没落。其原因有很多。流量、耗电、内存。。。
下面还是说下widget的使用吧：
首先看效果图：
1.首先在res文件夹下新建一个xml文件夹。注意是文件夹。然后在这个文件夹下新建一个xml文件：widget_provider.xml。resouce-type选择appwidget-provider，如图：
xml文件内容如下：
<?xml version="1.0" encoding="utf-8"?><appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android" android:minWidth="50dp" android:minHeight="50dp" android:updatePeriodMillis="10000" android:initialLayout="@layout/main"/>
2.修改layout文件夹的main.xml文件：
<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" android:background="@drawable/git" ><TextView android:id="@+id/wordcup" android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="hello" android:textSize="12px" android:textColor="#ff0000" /></LinearLayout>
3.修改WidetDemo.java
package com.wf.mywidgetdemo;import java.util.Calendar;import java.util.Date;import java.util.GregorianCalendar;import java.util.Timer;import java.util.TimerTask;import android.appwidget.AppWidgetManager;import android.appwidget.AppWidgetProvider;import android.content.ComponentName;import android.content.Context;import android.widget.RemoteViews;public class WidetDemo extends AppWidgetProvider{ /** Called when the activity is first created. */ @Override public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) { Timer timer = new Timer(); timer.scheduleAtFixedRate(new MyTime(context,appWidgetManager), 1, 60000); super.onUpdate(context, appWidgetManager, appWidgetIds); } private class MyTime extends TimerTask{ RemoteViews remoteViews; AppWidgetManager appWidgetManager; ComponentName thisWidget; public MyTime(Context context,AppWidgetManager appWidgetManager){ this.appWidgetManager = appWidgetManager; remoteViews = new RemoteViews(context.getPackageName(),R.layout.main); thisWidget = new ComponentName(context,WidetDemo.class); } @Override public void run() { Date date = new Date(); Calendar calendar = new GregorianCalendar(2018,06,8); long days = (((calendar.getTimeInMillis()-date.getTime())/1000))/86400; remoteViews.setTextViewText(R.id.wordcup, "距离俄罗斯世界杯还有" + days+"天"); appWidgetManager.updateAppWidget(thisWidget, remoteViews); } }}4.修改AndroidManifest.xml文件：
<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.wf.mywidgetdemo" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="8" android:targetSdkVersion="18" /> <application android:allowBackup="true" android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" > <receiver android:name=".WidetDemo" android:label="@string/app_name"> <intent-filter> <action android:name="android.appwidget.action.APPWIDGET_UPDATE" /> </intent-filter> <meta-data android:name="android.appwidget.provider" android:resource="@xml/widget_provider" /> </receiver> </application></manifest>搞定。