android代码混淆Warning:okio.DeflaterSink: can't find referenced class

Android studio 代码混淆遇到的两个问题

1. 找不到app/build/intermediates/proguard-rules/release/aapt_rules.txt文件
   解决方法:Build->clean Project->Make Project

2. Information:Gradle tasks [:app:assembleRelease]
   Warning:okio.DeflaterSink: can’t find referenced class org.codehaus.mojo.animal_sniffer.IgnoreJRERequirement
   Warning:okio.Okio: can’t find referenced class java.nio.file.Files
   Warning:okio.Okio: can’t find referenced class java.nio.file.Path
   Warning:okio.Okio: can’t find referenced class java.nio.file.OpenOption
   Warning:okio.Okio: can’t find referenced class java.nio.file.Path
   Warning:okio.Okio: can’t find referenced class java.nio.file.OpenOption
   Warning:okio.Okio: can’t find referenced class org.codehaus.mojo.animal_sniffer.IgnoreJRERequirement
   Warning:okio.Okio: can’t find referenced class java.nio.file.Path
   Warning:okio.Okio: can’t find referenced class java.nio.file.OpenOption
   Warning:okio.Okio: can’t find referenced class java.nio.file.Path
   Warning:okio.Okio: can’t find referenced class java.nio.file.OpenOption
   Warning:okio.Okio: can’t find referenced class org.codehaus.mojo.animal_sniffer.IgnoreJRERequirement
   Warning:there were 14 unresolved references to classes or interfaces.
   Warning:Exception while processing task java.io.IOException: Please correct the above warnings first.
   Error:Execution failed for task ‘:app:transformClassesAndResourcesWithProguardForRelease’.

   Job failed, see logs for details

解决办法:在proguard-rule.pro文件下加一句 -dontwarn okio.**