android代码实现背景切换

在android 中，如果要实现点击按钮，切换背景xml配置为：

?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android"
    android:constantSize=["true" | "false"]
    android:dither=["true" | "false"]
    android:variablePadding=["true" | "false"] >
    <item
        android:drawable="@[package:]drawable/drawable_resource"
        android:state_pressed=["true" | "false"]
        android:state_focused=["true" | "false"]
        android:state_selected=["true" | "false"]
        android:state_checkable=["true" | "false"]
        android:state_checked=["true" | "false"]
        android:state_enabled=["true" | "false"]
        android:state_window_focused=["true" | "false"] />
</selector>

 这段xml转换成java代码为：

StateListDrawable drawable=new StateListDrawable();
drawable.addState(new int []{android.R.attr.state_pressed}, Drawable.createFromStream(getResources().getAssets().open("mlist1_focush.png"), "src"));
				drawable.addState(new int []{}, Drawable.createFromStream(getResources().getAssets().open("mlist1_unfocush.png"), "src"));

 然后  imageView.setBackgroundDrawable(drawable);

imageView.setBackgroundDrawable(drawable);

 这样就实现了同样的功能，可以用这listview等控件上，非常有用