平常我們都是用xml來建立編寫selector，最近由於專案需要，需要載入網路圖片，問題來了，既要設定drawableTop又要動態載入網路圖片？一開始想想沒招，後面查找了資料，發現我們平常寫的selector.xml其實也可以用程式碼實現，以下就是相關介紹：

selector.xml

<?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/woman_icon_select"/>
    <item android:state_pressed="false" android:drawable="@drawable/woman_icon_default"/>
</selector>

採用程式碼實現：

StateListDrawable drawable = new StateListDrawable();
Drawable selected = context.getResources().getDrawable(R.drawable.woman_icon_select
 
);
Drawable unSelected = context.getResources().getDrawable(R.drawable.woman_icon_default);
drawable.addState(new int[]{android.R.attr.state_pressed},
selected);
drawable.addState(new int[]{-android.R.attr.state_pressed},
unSelected);
tv.setCompoundDrawablesWithIntrinsicBounds(null, drawable, null, null
 
);

-android.R.attr.state_presses前面加負號代表xml中android:state_pressed="false"

注意裡面的“-”號，當XML的設定是false時，就需要使用資源符號的負值來設定。

載入網路圖片，記得不能主執行緒里加載轉化為Drawable，否則會導致異常：

new AsyncTask<Void, Void, Drawable>() {

    @Override
protected Drawable doInBackground(Void... params) {
        StateListDrawable drawable = new StateListDrawable();
Drawable selected = loadImageFromNetwork("http://img0.imgtn.bdimg.com/it/u=919099284,2188508604&fm=15&gp=0.jpg");
Drawable unSelected = loadImageFromNetwork("http://img14.360buyimg.com/n4/g15/M00/04/01/rBEhWlLorJcIAAAAAAKhgJm7YvkAAIPwAI8vyUAAqGY603.jpg");
drawable.addState(new int[]{android.R.attr.state_pressed},
selected);
drawable.addState(new int[]{},
unSelected);
        return drawable;
}

    @Override
protected void onPostExecute(Drawable drawable) {
        super.onPostExecute(drawable);
tv.setCompoundDrawablesWithIntrinsicBounds(null, drawable, null, null);
}

}.execute();

private Drawable loadImageFromNetwork(String address) {
    Drawable drawable = null;
    try {
        drawable = Drawable.createFromStream(new URL(address).openStream(), "image.jpg");
} catch (IOException e) {
        Log.d("test", e.getMessage());
}
    return drawable;
}