Jackson + ProGuard：不能反序列化使用自定义解串器的类

Question

我的应用使用Jackson。我得到了最小化，构建大多与此配置工作：

# don't obfuscate Jackson classes 
-keep class com.fasterxml.** { *; } 

# don't strip runtime annotations 
-keepattributes RuntimeVisibleAnnotations 

# keep members with Jackson annotations 
-keepclassmembers public class * { 
    @com.fasterxml.jackson.annotation.JsonCreator *; 
    @com.fasterxml.jackson.annotation.JsonProperty *; 
} 

但最小化版本是仍然无法反序列化使用自定义解串器，又使用一厂一类。工厂，反序列化器和映射器都是由Dagger2生产的。错误是：

com.fasterxml.jackson.databind.JsonMappingException: No suitable constructor found for type [simple type, class com.mycompany.myapp.c.y]: can not instantiate from JSON object (missing default constructor or creator, or perhaps need to add/enable type information?) 
      at [Source: N/A; line: -1, column: -1] 
      at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromObjectUsingNonDefault(Unknown Source) 
      at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(Unknown Source) 
      at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(Unknown Source) 
      at com.fasterxml.jackson.databind.ObjectMapper._readValue(Unknown Source) 
      at com.fasterxml.jackson.databind.ObjectMapper.readValue(Unknown Source) 
      at com.fasterxml.jackson.databind.ObjectMapper.treeToValue(Unknown Source) 
      at com.mycompany.myapp.c.x.a(Unknown Source) 
      at com.mycompany.myapp.c.x.a(Unknown Source) 
      at com.mycompany.myapp.c.x.deserialize(Unknown Source) 
      at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(Unknown Source) 
      at com.fasterxml.jackson.databind.ObjectMapper.readValue(Unknown Source) 
      at com.mycompany.myapp.c.ag.d(Unknown Source) 
      at com.mycompany.myapp.c.ag.a(Unknown Source) 
      at com.mycompany.myapp.c.at.run(Unknown Source) 
      at android.os.Handler.handleCallback(Handler.java:605) 
      at android.os.Handler.dispatchMessage(Handler.java:92) 
      at android.os.Looper.loop(Looper.java:137) 
      at android.app.ActivityThread.main(ActivityThread.java:4508) 
      at java.lang.reflect.Method.invokeNative(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:511) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:809) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:576) 
      at dalvik.system.NativeStart.main(Native Method) 

错误消息表明我的课没有默认构造函数，它的确如此，因为实例是由自定义解串器使用工厂创建。这在我禁用ProGuard时正常工作。我需要做些什么才能使它与ProGuard协同工作？

Answer 1

我无意中发现这个方便的故障排除技巧：

-keepnames class * { *; } 

这表明真正的罪魁祸首是我的自定义解串器内部的专用静态嵌套类。解决方法是从该类别说明符中删除public：

-keepclassmembers class * { 
    @com.fasterxml.jackson.annotation.JsonCreator *; 
    @com.fasterxml.jackson.annotation.JsonProperty *; 
}