Android:AppWidget，PendingIntent，RemoteViews用法

什么是AppWidget？AppWidget就是我们平常在桌面上见到的那种一个个的小窗口，利用这个小窗口可以给用户提供一些方便快捷的操作。本篇打算从以下几个点来介绍AppWidget:

      1.如何创建一个简单的AppWidget

      2.如何使得AppWidget与客户端程序交互

下面我们来创建一个简单的AppWidget

1、定义AppWidgetProviderInfor：在res/xml文件夹中定义一个名为 ：example_appwidget_info.xml，这个名字随便取。它是提供AppWidget元数据；设置在桌面上显示的大小 

example_appwidget_info.xml

 

<
appwidget-provider
 
xmlns:android
=
"http://schemas.android.com/apk/res/android"
    android:minWidth
=
"294dp"
    android:minHeight
=
"72dp"
    android:updatePeriodMillis
=
"86400000"
    android:initialLayout
=
"@layout/example_appwidget"
>
    <!-- initiallayout设置引用 的布局文件 -->
 </
appwidget-provider
>

2、为App Widget指定样式和布局；在桌面上显示的内容，布局，就像main.xml布局一样，做为example_appwidget_info.xml的 initialLayout参数的值，用这个布局文件来初始化example_appwidget_info.xml。

 

<?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"
    >
<TextView
    android:id="@+id/widgetTextId"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="firstWidgetText"
    android:background="#000000"
    />
</LinearLayout>

3、实现继承AppWidgetProvider这个类；

这个类有五个方法：都需要继承：（下面按照当第一次加载Widget到删除的时候，这些方法运行的顺序）

1、onReceive (Context  context, Intent  intent)   Implements onReceive(Context, Intent)  to dispatch calls to the various other methods on AppWidgetProvider.

2、onEnabled (Context  context)  Called in response to the ACTION_APPWIDGET_ENABLED  broadcast when the a AppWidget for this provider is instantiated. Override this method to implement your own AppWidget functionality.

3、onUpdate (Context  context, AppWidgetManager  appWidgetManager, int[] appWidgetIds)  Called in response to the ACTION_APPWIDGET_UPDATE  broadcast when this AppWidget provider is being asked to provide RemoteViews  for a set of AppWidgets. Override this method to implement your own AppWidget functionality.

4、onDeleted (Context  context, int[] appWidgetIds)  Called in response to the ACTION_APPWIDGET_DELETED  broadcast when one or more AppWidget instances have been deleted. Override this method to implement your own AppWidget functionality.

5、onDisabled (Context  context)  Called in response to the ACTION_APPWIDGET_DISABLED  broadcast, which is sent when the last AppWidget instance for this provider is deleted. Override this method to implement your own AppWidget functionality.

基中onReceive负责进行接受广播，控制运行哪一个函数，每一个操作都会首先运行这个方法，再调用其它的方法。所以在Widget一次加载到删除过程中，onReceive会执行4次；

如下图：注意message

下面看代码： ExampleAppWidgetProvider.java

 

public
 
class
 ExampleAppWidgetProvider 
extends
 AppWidgetProvider {
    @Override
    public
 
void
 onUpdate(Context context, AppWidgetManager appWidgetManager,
            int
[] appWidgetIds) {
        System.out.println("onupdate"
);
        super
.onUpdate(context, appWidgetManager, appWidgetIds);
    }

    @Override
    public
 
void
 onDeleted(Context context, 
int
[] appWidgetIds) {
        System.out.println("onDeleted"
);
        super
.onDeleted(context, appWidgetIds);
    }

    @Override
    public
 
void
 onDisabled(Context context) {
        System.out.println("onDisabled"
);
        super
.onDisabled(context);
    }

    @Override
    public
 
void
 onEnabled(Context context) {
        System.out.println("onEnabled"
);
        super
.onEnabled(context);
    }
}

在这个实例中，因为与Activity脱离关系，所以Activity不用更改，只是在应用系统中注册了一个与这个应用程序相关的AppWidget而已：结果：

下面再来看看如何在AppWidget中添加按钮，添加监听事件。

1、在example_appwidget_info.xml文件里添加Button迫使

2、添加TargetActivity

只是用来响应点击事件，在此例中没有实际意义

public
 
class
 TargetActivity 
extends
 Activity {
    @Override
    protected
 
void
 onCreate(Bundle savedInstanceState) {
        super
.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }
}

3、在AndroidManifest.xml文件注册TargetActivity

4、重写ExampleAppWidgetProvider类的onUpdate方法，在第一次创建WidGet的时候，向按钮添加监听。并用PendingIntent，和RemoteView两个类，对事件进行处理；

 

public
 
void
 onUpdate(Context context, AppWidgetManager appWidgetManager,
            int
[] appWidgetIds) {
        System.out.println("onupdated"
);

        for
 (
int
 i = 
0
; i <appWidgetIds.length; i++) {
            System.out.println(appWidgetIds[i]);
            //创建一个Intent对象
            Intent intent = new
 Intent(context,TargetActivity.
class
);
            //创建一个PendingIntent（有四种方法获取）
            PendingIntent pendingIntent = PendingIntent.getActivity(context, 0
, intent, 
0
);
            RemoteViews remoteViews = new
 RemoteViews(context.getPackageName(),R.layout.example_appwidget);
            //为按钮绑定事件处理器
            //第一个参数用来指定被绑定处理器的控件的ID
            //第二个参数用来指定当事件发生时，哪个PendingIntent将会被执行
            remoteViews.setOnClickPendingIntent(R.id.widgetButton, pendingIntent);
            //更新AppWidget
            //第一个参数用于指定被更新AppWidget的ID
            appWidgetManager.updateAppWidget(appWidgetIds[i], remoteViews);
        }
        super
.onUpdate(context, appWidgetManager, appWidgetIds);
    }

 

Called in response to the ACTION_APPWIDGET_DELETED  broadcast when one or more AppWidget instances have been deleted. Override this method to implement your own AppWidget functionality.

在实际应用在AppWidget更多的是利用广播机制Action进行处理的；下面我们来看看如何利用广播机制，单击改变AppWidget的内容；在上例 的基础上进行扩展：

1、AppWidget的布局文件：widget01.xml

<?
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"
    >
<
Button
 
android:id
=
"@+id/widgetButton"
    android:layout_width
=
"fill_parent"
    android:layout_height
=
"wrap_content"
    android:text
=
"@string/widget_button"
/>

<
TextView
 
android:id
=
"@+id/test_text"
    android:layout_width
=
"fill_parent"
    android:layout_height
=
"wrap_content"
    android:text
=
"@string/test_text"
    android:gravity
=
"center"
    android:textColor
=
"#fff"
/>
</
LinearLayout
>

其中的Button控件是测试按钮，TextView用来反应单击Button之后显示的内容变化；（这是给Button添加监听器，再利用Action广播。收onRecerve接收，做出动作）

2、修改AndroidManifest.xml

在Reservi里添加action，注册事件

<
receiver
 
android:name
=
"ExampleAppWidgetProvider"
>
<!--如果action匹配成功，就在此类中进行处理-->
    <
intent-filter
>
        <!--利用广播机制接收,onUpdate会接收广播。查看源码可收得知  Called in response to the ACTION_APPWIDGET_UPDATE
            broadcast when this AppWidget provider is being asked to provide RemoteViews
            for a set of AppWidgets. Override this method to implement your own AppWidget
            functionality. 这个也必须要，不然onRecerve不会调用 。-->
        <!--这是自定义的Action事件-->
<
action
 
android:name
=
"android.appwidget.action.APPWIDGET_UPDATE"
/>
        <
action
 
android:name
=
"learn.test.UPDATE_APP_WIDGET"
/>
    </
intent-filter
>
    <
meta-data
 
android:name
=
"android.appwidget.provider"
 
android:resource
=
"@xml/widget_test"
 
/>
</
receiver
>

3、修改ExampleAppWidgetProvider.java代码文件，如下：

public
 
class
 ExampleAppWidgetProvider 
extends
 AppWidgetProvider {
    //定义一个常量字符串，该常量用于命名Action
    private
 
static
 
final
 String UPDATE_ACTION = 
"learn.test.UPDATE_APP_WIDGET"
;

    @Override
    public
 
void
 onDeleted(Context context, 
int
[] appWidgetIds) {
        // TODO Auto-generated method stub
System.out.println("onDeleted"
);
        super
.onDeleted(context, appWidgetIds);
    }

    @Override
    public
 
void
 onDisabled(Context context) {
        // TODO Auto-generated method stub
System.out.println("onDisabled"
);
        super
.onDisabled(context);
    }

    @Override
    public
 
void
 onEnabled(Context context) {
        // TODO Auto-generated method stub
System.out.println("onEnabled"
);
        super
.onEnabled(context);
    }

    @Override
    public
 
void
 onReceive(Context context, Intent intent) {
        // TODO Auto-generated method stub
System.out.println("onReceive"
);

        String action = intent.getAction();
        if
 (UPDATE_ACTION.equals(action)) {
            RemoteViews remoteViews = new
 RemoteViews(context.getPackageName(),
                    R.layout.widget01);
            remoteViews.setTextViewText(R.id.test_text, "this is OnReceive"
);
            //getInstance(Context context)  Get the AppWidgetManager instance to use for the supplied Context object.静态方法。
            AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context);

            ComponentName componentName = new
 ComponentName(context,ExampleAppWidgetProvider.
class
);
            appWidgetManager.updateAppWidget(componentName, remoteViews);
        } else
 {
            super
.onReceive(context, intent);
这里一定要添加，eles部分，不然，onReceive不会去调用其它的方法。但是如果把这条语句放在外面，就会每次运行
onUpdate,onDeleted等方法，就会运行两次，因为UPDATE_ACTION.equals(action)配置成功会运行一
次，uper.onReceive(context, intent)配置成功又会运行一次，后都是系统自定义的。
        }
    }

    @Override
    public
 
void
 onUpdate(Context context, AppWidgetManager appWidgetManager,
            int
[] appWidgetIds) {
        // TODO Auto-generated method stub
System.out.println("onUpdated"
);

//创建一个Intent对象
        Intent intent = new
 Intent();
        //为Intent对象设置Action
        intent.setAction(UPDATE_ACTION);
        //使用getBroadcast方法，得到一个PendingIntent对象，当该对象执行时，会发送一个广播
        PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0
,
                intent, 0
);
        RemoteViews remoteViews = new
 RemoteViews(context.getPackageName(),
                R.layout.widget01);

        remoteViews.setOnClickPendingIntent(R.id.widgetButton, pendingIntent);
        appWidgetManager.updateAppWidget(appWidgetIds, remoteViews);
        super
.onUpdate(context, appWidgetManager, appWidgetIds);
    }

}

评论

1 楼 liurui89 2012-05-29