将工程混淆下，但是发现有如下的错误：
[java] Warning: android.support.v4.view.accessibility.AccessibilityNodeProviderCompatJellyBean$1: can't find superclass or interface android.view.accessibility.AccessibilityNodeProvider [java] Warning: android.support.v4.app.NavUtilsJB: can't find referenced method 'android.content.Intent getParentActivityIntent()' in class android.app.Activity [java] Warning: android.support.v4.app.NavUtilsJB: can't find referenced method 'boolean shouldUpRecreateTask(android.content.Intent)' in class android.app.Activity [java] Warning: android.support.v4.app.NavUtilsJB: can't find referenced method 'boolean navigateUpTo(android.content.Intent)' in class android.app.Activity [java] Warning: android.support.v4.app.NavUtilsJB: can't find referenced field 'java.lang.String parentActivityName' in class android.content.pm.ActivityInfo [java] Warning: android.support.v4.app.NotificationCompatJellybean: can't find referenced method 'android.app.Notification$Builder setSubText(java.lang.CharSequence)' in class android.app.Notification$Builder [java] Warning: android.support.v4.app.NotificationCompatJellybean: can't find referenced method 'android.app.Notification$Builder setUsesChronometer(boolean)' in class android.app.Notification$Builder [java] Warning: android.support.v4.app.NotificationCompatJellybean: can't find referenced method 'android.app.Notification$Builder setPriority(int)' in class android.app.Notification$Builder [java] Warning: android.support.v4.app.NotificationCompatJellybean: can't find referenced method 'android.app.Notification$Builder addAction(int,java.lang.CharSequence,android.app.PendingIntent)' in class android.app.Notification$Builder
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由于之前混淆这个 android-support-v4.jar包是没有问题的，
可想问题出现：目前的这个android-support-v4.jar JAR包上，果然，当初建工程的时候，引导工程默认是
使用最新的API-17来建工程的，所以系统默认使用支持4.1 Jelly Bean 的android-support-v4.jar JAR包,
打包的时候 API-level调到 >= 16即可,或者将 /libs/android-support-v4.jar 替换成较老版本的。