用代码来实现selector

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平常我们都是用xml来创建编写selector，最近由于项目需要，需要加载网络图片，问题来了，既要设置drawableTop又要动态加载网络图片？一开始想想没招，后面查找了资料，发现我们平常写的selector.xml其实也可以用代码实现，以下就是相关介绍：

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>

采用代码实现：

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前面加负号代表xml中android:state_pressed="false"

注意里面的“-”号，当XML的设定是false时，就需要使用资源符号的负值来设定。

加载网络图片，记得不能主线程里加载转化为Drawable，否则会导致异常：

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();

//通过网络地址转为Drawable

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;}

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