AndroidStudio混淆时候报错java.io.IOException: Please correct the above warnings first

在用AndroidStudio混淆代码的时候，在添加了一些不须要混淆的文件以后，在编译运行的时候会发生这样的warning:

Warning: library class android.content.res.XmlResourceParser extends or implements program class org.xmlpull.v1.XmlPullParser  
Warning: library class android.content.Intent depends on program class org.xmlpull.v1.XmlPullParser  
Warning: library class android.content.IntentFilter depends on program class org.xmlpull.v1.XmlPullParser  
Warning: library class android.content.res.ColorStateList depends on program class org.xmlpull.v1.XmlPullParser  
Warning: library class android.graphics.drawable.BitmapDrawable depends on program class org.xmlpull.v1.XmlPullParser  
Warning: library class android.graphics.drawable.ColorDrawable depends on program class org.xmlpull.v1.XmlPullParser  
Warning: library class android.graphics.drawable.Drawable depends on program class org.xmlpull.v1.XmlPullParser  
Warning: library class android.graphics.drawable.Drawable depends on program class org.xmlpull.v1.XmlPullParser  
Warning: library class android.graphics.drawable.Drawable depends on program class org.xmlpull.v1.XmlPullParser  
Warning: library class android.util.Xml depends on program class org.xmlpull.v1.XmlPullParser  
Warning: library class android.util.Xml depends on program class org.xmlpull.v1.XmlPullParser  
Warning: library class android.view.LayoutInflater depends on program class org.xmlpull.v1.XmlPullParser  
Warning: library class android.view.LayoutInflater depends on program class org.xmlpull.v1.XmlPullParser  

尽管是waring，可是程序运行不起来，如今有个解决办法就是:

在proguard-rules.pro中加上一行:

-ignorewarnings