java - Gson IllegalStateException 预期为 BEGIN_OBJECT，但当数据类型为 CharSequence 时为 STRING

Question

假设我有一个简单的数据类

data class Car(var make: String)

和一个 Json 字符串

val json = "[{'make':'foo'}, {'make':'bar'}]"

当我使用Gson反序列化字符串时

val carList : MutableList<Car> = gson.fromJson(json, Array<Car>::class.java).toMutableList()

它按预期工作。但是当我将 Car 中 make 的数据类型更改为 CharSequence

data class Car(var make: CharSequence)

还有 GsonBuilder

val builder = GsonBuilder()
builder.registerTypeAdapter(CharSequence::class.java, object : InstanceCreator<CharSequence> {
    override fun createInstance(type: Type?): CharSequence {
        return String()
    }
})
gson = builder.create()

我收到 com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 11 path $[0].make

一直在努力使其与 CharSequence 类型一起工作，任何建议都值得赞赏。

Answer 1

您必须创建适当的JsonDeserializer。不是InstanceCreator。例如:

builder.registerTypeAdapter(CharSequence::class.java, object : JsonDeserializer<CharSequence> {
    override fun deserialize(
        json: JsonElement?,
        typeOfT: Type?,
        context: JsonDeserializationContext?
    ): CharSequence = json?.asString ?: ""
})