Jackson + ProGuard：无法反序列化使用自定义反序列化器的类

Question

我的应用程序使用 Jackson。 我得到了最小化的构建，主要使用此配置：

# 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 *;
}

但是最小化构建仍然无法反序列化使用自定义反序列化器的类，而自定义反序列化器又使用工厂。 工厂、反序列化器、映射器都是Dagger2制作的。 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)

错误消息表明我的类缺少默认构造函数，确实如此，因为实例是由自定义反序列化器使用工厂创建的。 当我禁用 ProGuard 时，这工作正常。 我需要做什么才能使其与 ProGuard 一起使用？

Answer 1

我无意中发现了这个方便的故障排除技巧：

-keepnames class * { *; }

这揭示了真正的罪魁祸首是我的自定义反序列化器中的私有静态嵌套类。 解决方案是从该选项的类说明符中删除

public

：

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

Answer 2

只需保留自定义解串器类：

-keep class * extends com.fasterxml.jackson.databind.JsonDeserializer { *; }

并保留模型：

-keep class com.your.model.path.ModelClass { *; }