android实现按键效果

有两种方法。

第一种:
该方法通过onTouch来实现

    btn3 = (ImageButton) findViewById(R.id.ImageButton03);  
    btn3.setOnTouchListener(touchListener3);  
    View.OnTouchListener touchListener = new OnTouchListener() {  
    @Override  
    public boolean onTouch(View v, MotionEvent event) {  
    ImageButton imageBtn = (ImageButton) v;  
    if(event.getAction() == MotionEvent.ACTION_DOWN){  
    //更改为按下时的背景图片  
    imageBtn .setImageResource(R.drawable.pressed);  
    }else if(event.getAction() == MotionEvent.ACTION_UP){  
    //改为抬起时的图片  
    imageBtn .setImageResource(R.drawable.released);  
    }  
    return false;  
    }  
    };  

第二种:
通过XML来实现：

将下面的文件放在drawable目录下面。命名为button_add_x.xml

<?xml version="1.0" encoding="UTF-8"?>  
<selector xmlns:android="http://schemas.android.com/apk/res/android">  
<item           
android:state_pressed="false"  
android:drawable="@drawable/button_add" />  
<item           
android:state_pressed="true"  
android:drawable="@drawable/button_add_pressed" />  
<item           
android:state_focused="true"  
android:drawable="@drawable/button_add_pressed" />  
<item           
android:drawable="@drawable/button_add" />  
</selector>

使用的时候：

<ImageButton  
android:id="@+id/ImageButton"  
android:layout_width="wrap_content"  
android:layout_height="wrap_content"  
android:background="#00000000"  
android:src="@drawable/button_add_x"  
>  
</ImageButton>

下面详细介绍下几种触发属性：

1）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。

2）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。

3）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。

4）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。

5）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。

6）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。

7）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。