1. res/raw下：

        InputStream is = getResources().openRawResource(R.id.xxx);

2.res/xml下：

       XmlResourceParser xmlResourceParser = getResources().getXml(R.xml.xxx);

3.src/下：

        InputStream is = getClass().getClassLoader().getResourceAsStream("xxx.xml");

4.assets/下：

        AssetManager assets = getAssets();

        InputStream is = assets.open("xxx.xml");