android背景选择器selector用法汇总

在res/drawable文件夹新增一个文件，此文件设置了图片的触发状态，你可以设置 state_pressed，state_checked，state_pressed，state_selected，state_focused，state_enabled 等几个状态：

android:state_pressed

Boolean. "true" if this item should be used when the object is pressed (such as when a button is touched/clicked); "false" if this item should be used in the default, non-pressed state.

如果是true，当被点击时显示该图片，如果是false没被按下时显示默认。

android:state_focused

Boolean. "true" if this item should be used when the object is focused (such as when a button is highlighted using the trackball/d-pad); "false" if this item should be used in the default, non-focused state.

true，获得焦点时显示；false，没获得焦点显示默认。

android:state_selected

Boolean. "true" if this item should be used when the object is selected (such as when a tab is opened); "false" if this item should be used when the object is not selected.

true，当被选择时显示该图片；false，当未被选择时显示该图片。

android:state_checkable

Boolean. "true" if this item should be used when the object is checkable; "false" if this item should be used when the object is not checkable. (Only useful if the object can transition between a checkable and non-checkable widget.)

true，当CheckBox能使用时显示该图片；false，当CheckBox不能使用时显示该图片。

android:state_checked

Boolean. "true" if this item should be used when the object is checked; "false" if it should be used when the object is un-checked.

true，当CheckBox选中时显示该图片；false，当CheckBox为选中时显示该图片。

android:state_enabled

Boolean. "true" if this item should be used when the object is enabled (capable of receiving touch/click events); "false" if it should be used when the object is disabled.

true，当该组件能使用时显示该图片；false，当该组件不能使用时显示该图片。

android:state_window_focused

Boolean. "true" if this item should be used when the application window has focus (the application is in the foreground), "false" if this item should be used when the application window does not have focus (for example, if the notification shade is pulled down or a dialog appears).

true，当此activity获得焦点在最前面时显示该图片；false，当没在最前面时显示该图片。

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true"
          android:drawable="@drawable/button_pressed"/><!-- pressed -->
    <item android:state_focused="true"
          android:drawable="@drawable/button_focused"/><!-- focused -->
    <item android:drawable="@drawable/button_normal"/><!-- default -->
</selector>

一．创建xml文件，位置：drawable/xxx.xml,同目录下记得要放相关图片
<?xml version="1.0" encoding="utf-8" ?>  
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<!-- 默认时的背景图片--> 
  <item android:drawable="@drawable/pic1" />   
<!-- 没有焦点时的背景图片 --> 
  <item android:state_window_focused="false"  
        android:drawable="@drawable/pic1" />  
<!-- 非触摸模式下获得焦点并单击时的背景图片 --> 
  <item android:state_focused="true" android:state_pressed="true"   android:drawable= "@drawable/pic2" />
<!-- 触摸模式下单击时的背景图片--> 
<item android:state_focused="false" android:state_pressed="true"   android:drawable="@drawable/pic3" /> 
<!--选中时的图片背景--> 
  <item android:state_selected="true"   android:drawable="@drawable/pic4" />  
<!--获得焦点时的图片背景--> 
  <item android:state_focused="true"   android:drawable="@drawable/pic5" />  
</selector>
二.使用xml文件：
1.方法一：在listview中配置android:listSelector="@drawable/xxx
或者在listview的item中添加属性android：background="@drawable/xxx"
2.方法二：Drawable drawable = getResources().getDrawable(R.drawable.xxx); 
       ListView.setSelector(drawable);但是这样会出现列表有时候为黑的情况，需要加上：android:cacheColorHint="@android:color/transparent"使其透明。

相关属性：
android:state_selected是选中
android:state_focused是获得焦点
android:state_pressed是点击
android:state_enabled是设置是否响应事件,指所有事件
根据这些状态同样可以设置button的selector效果。也可以设置selector改变button中的文字状态。

以下是配置button中的文字效果：
drawable/button_font.xml
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_selected="true" android:color="#FFF" />
    <item android:state_focused="true" android:color="#FFF" />
    <item android:state_pressed="true" android:color="#FFF" />
    <item android:color="#000" />
</selector>
Button还可以实现更复杂的效果，例如渐变
drawable/button_color.xml
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">         /
<item android:state_pressed="true">//定义当button 处于pressed 状态时的形态。
                <shape>
                <gradient  android:startColor="#8600ff" />
                      <stroke   android:width="2dp" android:color="#000000" />
                       <corners android:radius="5dp" /> 
                       <padding android:left="10dp" android:top="10dp"
                                android:bottom="10dp" android:right="10dp"/> 
                 </shape>
</item>
<item android:state_focused="true">//定义当button获得 focus时的形态
                 <shape>
                       <gradient android:startColor="#eac100"/>
                        <stroke android:width="2dp" android:color="#333333"  color="#ffffff"/>
                         <corners android:radius="8dp" />  
                         <padding android:left="10dp" android:top="10dp"
                                  android:bottom="10dp" android:right="10dp"/>                  
                </shape>
</item>
</selector>
最后，需要在包含 button的xml文件里添加两项。例如main.xml 文件，需要在<Button />里加两项android：focusable="true" android:background="@drawable/button_color"