用于编译Android应用程序的Ant脚本工作正常，但在将Google Play Services库更新到5.0 (revision 18)后，ProGuard失败，输出如下:
-obfuscate:
[mkdir] Created dir: /srv2/jenkins/jobs/CCNF Google only/workspace/trunk/org.digitalcure.ccnf.app/bin/proguard
[jar] Building jar: /srv2/jenkins/jobs/CCNF Google only/workspace/trunk/org.digitalcure.ccnf.app/bin/proguard/original.jar
[proguard] ProGuard, version 4.7
[proguard] Reading input...
[proguard] Reading program jar [/srv2/jenkins/jobs/CCNF Google only/workspace/trunk/org.digitalcure.ccnf.app/bin/proguard/original.jar]
[proguard] Reading program jar [/srv2/jenkins/jobs/CCNF Google only/workspace/trunk/org.digitalcure.android.common/bin/classes.jar]
[proguard] Reading program jar [/srv2/jenkins/jobs/CCNF Google only/workspace/trunk/google-play-services_lib/bin/classes.jar]
[proguard] Reading program jar [/srv2/jenkins/jobs/CCNF Google only/workspace/trunk/android-support-v7-appcompat/bin/classes.jar]
[proguard] Reading program jar [/srv2/jenkins/jobs/CCNF Google only/workspace/trunk/android-support-v7-appcompat/libs/android-support-v7-appcompat.jar]
[proguard] Reading program jar [/srv2/jenkins/jobs/CCNF Google only/workspace/trunk/android-support-v7-appcompat/libs/android-support-v4.jar]
[proguard] Reading program jar [/srv2/jenkins/jobs/CCNF Google only/workspace/trunk/google-play-services_lib/libs/google-play-services.jar]
[proguard] Reading library jar [/srv/jenkins/tools/android-sdk-linux/platforms/android-17/android.jar]
[proguard] Initializing...
[proguard] Warning: com.google.android.gms.cast.TextTrackStyle: can't find referenced class android.view.accessibility.CaptioningManager
[proguard] Warning: com.google.android.gms.cast.TextTrackStyle: can't find referenced class android.view.accessibility.CaptioningManager$CaptionStyle
[proguard] Warning: com.google.android.gms.cast.TextTrackStyle: can't find referenced class android.view.accessibility.CaptioningManager$CaptionStyle
[proguard] Warning: com.google.android.gms.cast.TextTrackStyle: can't find referenced class android.view.accessibility.CaptioningManager$CaptionStyle
[proguard] Warning: com.google.android.gms.cast.TextTrackStyle: can't find referenced class android.view.accessibility.CaptioningManager$CaptionStyle
[proguard] Warning: com.google.android.gms.cast.TextTrackStyle: can't find referenced class android.view.accessibility.CaptioningManager$CaptionStyle
[proguard] Warning: com.google.android.gms.cast.TextTrackStyle: can't find referenced class android.view.accessibility.CaptioningManager
[proguard] Warning: com.google.android.gms.cast.TextTrackStyle: can't find referenced class android.view.accessibility.CaptioningManager
[proguard] Warning: com.google.android.gms.cast.TextTrackStyle: can't find referenced class android.view.accessibility.CaptioningManager$CaptionStyle
[proguard] Note: android.support.v4.app.NotificationCompatJellybean: can't find dynamically referenced class android.app.Notification$Action
[proguard] Note: android.support.v4.text.ICUCompatIcs: can't find dynamically referenced class libcore.icu.ICU
[proguard] Note: com.google.android.gms.maps.internal.u: can't find dynamically referenced class com.google.android.gms.maps.internal.CreatorImplGmm6
[proguard] Note: com.google.android.gms.maps.internal.u: can't find dynamically referenced class com.google.android.gms.maps.internal.CreatorImpl
[proguard] Note: the configuration refers to the unknown class 'com.google.vending.licensing.ILicensingService'
[proguard] Note: the configuration refers to the unknown class 'com.android.vending.licensing.ILicensingService'
[proguard] Note: the configuration refers to the unknown class 'Object'
[proguard] Maybe you meant the fully qualified name 'java.lang.Object'?
[proguard] Note: the configuration refers to the unknown class 'fqcn.of.javascript.interface.for.webview'
[proguard] Note: the configuration keeps the entry point 'com.google.ads.AdSize { AdSize(com.google.android.gms.ads.AdSize); }', but not the descriptor class 'com.google.android.gms.ads.AdSize'
[proguard] Note: the configuration keeps the entry point 'com.google.ads.mediation.admob.AdMobAdapter { com.google.android.gms.ads.AdRequest a(android.content.Context,com.google.android.gms.ads.mediation.MediationAdRequest,android.os.Bundle,android.os.Bundle); }', but not the descriptor class 'com.google.android.gms.ads.mediation.MediationAdRequest'
[proguard] Note: the configuration keeps the entry point 'com.google.ads.mediation.admob.AdMobAdapter { void requestBannerAd(android.content.Context,com.google.android.gms.ads.mediation.MediationBannerListener,android.os.Bundle,com.google.android.gms.ads.AdSize,com.google.android.gms.ads.mediation.MediationAdRequest,android.os.Bundle); }', but not the descriptor class 'com.google.android.gms.ads.mediation.MediationBannerListener'
[proguard] Note: the configuration keeps the entry point 'com.google.ads.mediation.admob.AdMobAdapter { void requestBannerAd(android.content.Context,com.google.android.gms.ads.mediation.MediationBannerListener,android.os.Bundle,com.google.android.gms.ads.AdSize,com.google.android.gms.ads.mediation.MediationAdRequest,android.os.Bundle); }', but not the descriptor class 'com.google.android.gms.ads.AdSize'
[proguard] Note: the configuration keeps the entry point 'com.google.ads.mediation.admob.AdMobAdapter { void requestBannerAd(android.content.Context,com.google.android.gms.ads.mediation.MediationBannerListener,android.os.Bundle,com.google.android.gms.ads.AdSize,com.google.android.gms.ads.mediation.MediationAdRequest,android.os.Bundle); }', but not the descriptor class 'com.google.android.gms.ads.mediation.MediationAdRequest'
[proguard] Note: the configuration keeps the entry point 'com.google.ads.mediation.admob.AdMobAdapter { void requestInterstitialAd(android.content.Context,com.google.android.gms.ads.mediation.MediationInterstitialListener,android.os.Bundle,com.google.android.gms.ads.mediation.MediationAdRequest,android.os.Bundle); }', but not the descriptor class 'com.google.android.gms.ads.mediation.MediationInterstitialListener'
[proguard] Note: the configuration keeps the entry point 'com.google.ads.mediation.admob.AdMobAdapter { void requestInterstitialAd(android.content.Context,com.google.android.gms.ads.mediation.MediationInterstitialListener,android.os.Bundle,com.google.android.gms.ads.mediation.MediationAdRequest,android.os.Bundle); }', but not the descriptor class 'com.google.android.gms.ads.mediation.MediationAdRequest'
[proguard] Note: the configuration keeps the entry point 'com.google.ads.mediation.admob.AdMobAdapter$a { AdMobAdapter$a(com.google.ads.mediation.admob.AdMobAdapter,com.google.android.gms.ads.mediation.MediationBannerListener); }', but not the descriptor class 'com.google.android.gms.ads.mediation.MediationBannerListener'
[proguard] Note: the configuration keeps the entry point 'com.google.ads.mediation.admob.AdMobAdapter$b { AdMobAdapter$b(com.google.ads.mediation.admob.AdMobAdapter,com.google.android.gms.ads.mediation.MediationInterstitialListener); }', but not the descriptor class 'com.google.android.gms.ads.mediation.MediationInterstitialListener'
[proguard] Note: the configuration keeps the entry point 'com.google.ads.mediation.customevent.CustomEventAdapter { void requestBannerAd(com.google.ads.mediation.MediationBannerListener,android.app.Activity,com.google.ads.mediation.customevent.CustomEventServerParameters,com.google.ads.AdSize,com.google.ads.mediation.MediationAdRequest,com.google.android.gms.ads.mediation.customevent.CustomEventExtras); }', but not the descriptor class 'com.google.android.gms.ads.mediation.customevent.CustomEventExtras'
[proguard] Note: the configuration keeps the entry point 'com.google.ads.mediation.customevent.CustomEventAdapter { void requestInterstitialAd(com.google.ads.mediation.MediationInterstitialListener,android.app.Activity,com.google.ads.mediation.customevent.CustomEventServerParameters,com.google.ads.mediation.MediationAdRequest,com.google.android.gms.ads.mediation.customevent.CustomEventExtras); }', but not the descriptor class 'com.google.android.gms.ads.mediation.customevent.CustomEventExtras'
[proguard] Note: there were 4 references to unknown classes.
[proguard] You should check your configuration for typos.
[proguard] Note: there were 11 unkept descriptor classes in kept class members.
[proguard] You should consider explicitly keeping the mentioned classes
[proguard] (using '-keep').
[proguard] Note: there were 5 unresolved dynamic references to classes or interfaces.
[proguard] You should check if you need to specify additional program jars.
[proguard] Warning: there were 9 unresolved references to classes or interfaces.
[proguard] You may need to specify additional library jars (using '-libraryjars').
与之前的(工作)输出比较，以下行是新的:
[proguard] Warning: com.google.android.gms.cast.TextTrackStyle: can't find referenced class android.view.accessibility.CaptioningManager
[proguard] Warning: com.google.android.gms.cast.TextTrackStyle: can't find referenced class android.view.accessibility.CaptioningManager$CaptionStyle
[proguard] Warning: com.google.android.gms.cast.TextTrackStyle: can't find referenced class android.view.accessibility.CaptioningManager$CaptionStyle
[proguard] Warning: com.google.android.gms.cast.TextTrackStyle: can't find referenced class android.view.accessibility.CaptioningManager$CaptionStyle
[proguard] Warning: com.google.android.gms.cast.TextTrackStyle: can't find referenced class android.view.accessibility.CaptioningManager$CaptionStyle
[proguard] Warning: com.google.android.gms.cast.TextTrackStyle: can't find referenced class android.view.accessibility.CaptioningManager$CaptionStyle
[proguard] Warning: com.google.android.gms.cast.TextTrackStyle: can't find referenced class android.view.accessibility.CaptioningManager
[proguard] Warning: com.google.android.gms.cast.TextTrackStyle: can't find referenced class android.view.accessibility.CaptioningManager
[proguard] Warning: com.google.android.gms.cast.TextTrackStyle: can't find referenced class android.view.accessibility.CaptioningManager$CaptionStyle
[proguard] Note: android.support.v4.app.NotificationCompatJellybean: can't find dynamically referenced class android.app.Notification$Action
加上输出末尾的错误信息。
发生了什么事?似乎android.view.accessibility.CaptioningManager是在API级别19时引入的。
我注意到Android支持库的目标版本从16更改为19(同时更新为修订版20)。我的应用程序是基于目标版本17构建的。所以我把主app项目的目标版本从17改成了19，现在一切都好了。就是这样!
对于@stefan222的回答不起作用的人，您可以添加
-dontwarn com.google.android.gms.cast.**
到proguard.cfg
这样做风险自负。如果你添加了这些内容，请确保彻底测试你的应用。
对于想要摆脱警告的人:
所以根本不会显示任何警告
-dontwarn com.google.android.gms.**