java代码中实现android背景选择的selector-StateListDrawable的应用

http://www.jcodecraeer.com/a/anzhuokaifa/androidkaifa/2014/0924/1712.html

 

private StateListDrawable addStateDrawable(Context context,  int idNormal, int idPressed, int idFocused) {
    StateListDrawable sd = new StateListDrawable();
    Drawable normal = idNormal == -1 ? null : context.getResources().getDrawable(idNormal);
    Drawable pressed = idPressed == -1 ? null : context.getResources().getDrawable(idPressed);
    Drawable focus = idFocused == -1 ? null : context.getResources().getDrawable(idFocused);
    //注意该处的顺序，只要有一个状态与之相配，背景就会被换掉
    //所以不要把大范围放在前面了，如果sd.addState(new[]{},normal)放在第一个的话，就没有什么效果了
    sd.addState(new int[]{android.R.attr.state_enabled, android.R.attr.state_focused}, focus);
    sd.addState(new int[]{android.R.attr.state_pressed, android.R.attr.state_enabled}, pressed);
    sd.addState(new int[]{android.R.attr.state_focused}, focus);
    sd.addState(new int[]{android.R.attr.state_pressed}, pressed);
    sd.addState(new int[]{android.R.attr.state_enabled}, normal);
    sd.addState(new int[]{}, normal);
    return sd;
}