android 所有焦点问题汇总【Focus】

一. 主动获取焦点

setFocusable(true);    //  是设置能否获得焦点而已。.

requestFocus();          //是让控件得到焦点

requestFocusInWindow()  //的作用应该是获取窗口的焦点

二:子类是否获取焦点

android:descendantFocusability
  
  
  
  

   
   
   
   
Defines the relationship between the ViewGroup and its descendants when looking for a View to take focus.
   
   
   
   
Must be one of the following constant values.
   
   
   
   
 
    
 
      
      
      
     
 
      
 
       
Constant
 
       
Value
 
       
Description
 
      
 
      
 
       
beforeDescendants
 
       
  0
 
       
The ViewGroup will get focus before any of its descendants.
 
      
 
      
 
       
afterDescendants
 
       
  1
 
       
The ViewGroup will get focus only if none of its descendants want it.
 
      
 
      
 
       
blocksDescendants
 
       
  2
 
       
The ViewGroup will block its descendants from receiving focus
 
      
 
     
 
    
 
   
   
   
   
   

       
   
   
   
   
   

     具体可以看另外一篇文章： android:descendantFocusability用法简析 
   
  
  
  
  

 

三：监听activity获取/失去焦点（onWindowFocusChanged）

作用：1.可以监听activity获取/失去焦点 【hasFocus： true 获取焦点， false失去焦点】

            2.判断activity加载完成（当所有生命周期完成后调用该方法）

@Override

public void onWindowFocusChanged(boolean hasFocus) {
    // TODO Auto-generated method stub
    super.onWindowFocusChanged(hasFocus);
}