Android源代码中引用@hide类出现引用异常的问题error: cannot find symbol

    自己开发的APP在Android中使用一些系统隐藏的类

    

   编译的时候报错，出现如下异常

error: cannot find symbol
import android.net.EthernetManager;
                  ^
  symbol:   class EthernetManager
  location: package android.net

   原因是由于app在Android.mk中配置了LOCAL_SDK_VERSION 属性，将其去掉，然后重新编译，出现

Warning: there were 69 unresolved references to classes or interfaces.
         You may need to add missing library jars or update their versions.
         If your code works fine without the missing classes, you can suppress
         the warnings with '-dontwarn' options.
         (http://proguard.sourceforge.net/manual/troubleshooting.html#unresolvedclass)
Warning: there were 489 instances of library classes depending on program classes.
         You must avoid such dependencies, since the program classes will
         be processed, while the library classes will remain unchanged.
         (http://proguard.sourceforge.net/manual/troubleshooting.html#dependency)
Error: Please correct the above warnings first.
build/core/java.mk:460: recipe for target 'out/target/common/obj/APPS/AP4_intermediates/proguard.classes.jar' failed

 原因是由于混淆导致的warning太多，可以在Android.mk文件中的LOCAL_PROGUARD_FLAG_FILES指定的文件中（如果没有可以新增一条LOCAL_PROGUARD_FLAG_FILES属性）忽略掉错误

-ignorewarnings

当然，也可以按照提示在proguard文件中按包名忽略错误

#对应的warning的包名
-dontwarn com.** 

再次编译，即可成功