Android widget learning Summary

1. widget design steps
Three XML files need to be modified, one class:

1) The first XML is the layout XML file (for example, Main. XML), which belongs to this widget. Generally, if you use this part to display the time, it is okay to declare a textview in the layout XML.

2) The second XML is widget_provider.xml, which is mainly used to declare an appwidget. Layout specifies the above main. xml.

3) The third XML is androidmanifest. XML, which registers broadcastreceiver information.

4) the last class is used for some business logic operations.Let it inherit the appwidgetprovider class.Appwidgetprovider has many methods. Generally, we only override the onupdate (context, appwidgetmanager, int []) method.

2.CodeCase

1)Main. 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/tvcurrtime"  Android: layout_width = "Wrap_content"  Android: layout_height  = "Wrap_content"  Android: Text  = "@ String/hello"   
Android: textcolor  = "@ Color/Black"  />  
 </  Linearlayout  >  

2)Hello_widget_provider.xml

<?XML version = "1.0" encoding = "UTF-8"?> 
<Appwidget-providerXmlns: Android= "Http://schemas.android.com/apk/res/android" 
Android: minwidth= "146dip"Android: minheight= "72dip"Android: initiallayout= "@ Layout/main"> 
</Appwidget-provider> 
 

3)Androidmanifest. xml

<?  XML version = "1.0" encoding = "UTF-8"  ?>  
 <  Manifest  Xmlns: Android  = "Http://schemas.android.com/apk/res/android"  Package  = "Com. Woody. testwidget"  Android: versioncode  = "1"   
Android: versionname  = "1.0"  >  
<  Application  Android: icon  = "@ Drawable/icon"  Android: Label  = "@ String/app_name"  >  
 <  Cycler  Android: Name  = ". Hellowidgetprovider"  Android: Label  = "@ String/app_name"  >   <! -- Hellowidgetprovider is the class (Business Processing)  -->  
 <  Intent-Filter  >  
 <  Action  Android: Name  = "Android. appwidget. Action. appwidget_update"   />   <! --  The specified  -->  
 </ Intent-Filter  >  
 <  Meta-data  Android: Name  = "Android. appwidget. provider" Android: Resource = "@ XML/hello_widget_provider"/> <! -- Specify the widget -->  
 </  Cycler  >  
 </  Application  >  
</  Manifest  >  

4)Hellowidgetprovider. Java

 
Public ClassHellowidgetproviderExtendsAppwidgetprovider {
 

/** called when the activity is first created. */
@ override
Public void onupdate (context, appwidgetmanager, int [] appwidgetids) {
timer = New timer ();
timer. scheduleatfixedrate ( New mytime (context, appwidgetmanager), 1, 1000);
}

Public ClassMytimeExtendsTimertask {
Remoteviews;
Appwidgetmanager;
Componentname thiswidget;
Dateformat format = simpledateformat. gettimeinstance (simpledateformat. Medium, locale. getdefault ());

 
PublicMytime (context, appwidgetmanager ){
This. Appwidgetmanager = appwidgetmanager;
Remoteviews =NewRemoteviews (context. getpackagename (), R. layout. Main );
Thiswidget =NewComponentname (context, hellowidgetprovider.Class);
}
 

@ Override
Public VoidRun (){
Remoteviews. settextviewtext (R. Id. tvcurrtime, "time =" + format. Format (NewDate ()));
Appwidgetmanager. updateappwidget (thiswidget, remoteviews );
}
}
}
 

Code explanation:Remoteview is used to describe the view displayed by a broken process. That is to say, this view is displayed by another process. It is inflate in the layout resource file. It also provides some basic operations that can be used to modify the View content.

Appwidget --- remoteview,Appwidgetprovider is a brocasereceiver that only receives the Enable, update, disale, and delete messages, while the real display interface is appwidgethostview (implemented in launcher ).Communicate through remoteview. Remoteview is used to tell launcher what the appwidget you want is.