android高手之路之Android Widget

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。