是的,您可以创建一个自定义类型适配器来根据layerType
解析JSON,方法如下:
是的,您可以创建一个自定义类型适配器来根据layerType
解析JSON,方法如下:
class LayerAdapter {
@FromJson
fun fromJson(layerJson: LayerJson): Layer = when (layerJson.layerType) {
LayerType.SHAPE -> ShapeLayer(layerJson.layerType, layerJson.shape ?: "")
LayerType.TEXT -> TextLayer(layerJson.layerType, layerJson.text ?: "")
LayerType.IMAGE -> ImageLayer(layerJson.layerType, layerJson.image ?: "")
}
@ToJson
fun toJson(layer: Layer): LayerJson = when (layer) {
is ShapeLayer -> LayerJson(layer.type, shape = layer.shape)
is TextLayer -> LayerJson(layer.type, text = layer.text)
is ImageLayer -> LayerJson(layer.type, image = layer.image)
else -> throw RuntimeException("Not support data type")
}
}
这里我对您的数据类进行了一些更改,以增加其清晰度(每个Layer
类型都添加了一个额外的属性,例如ShapeLayer
的shape
):
sealed class Layer
data class ShapeLayer(val type: LayerType, val shape: String) : Layer()
data class TextLayer(val type: LayerType, val text: String) : Layer()
data class ImageLayer(val type: LayerType, val image: String) : Layer()
data class LayerJson(val layerType: LayerType, val shape: String? = null, val text: String? = null, val image: String? = null) : Layer()
enum class LayerType {
SHAPE, TEXT, IMAGE
}
测试代码:
val moshi = Moshi.Builder()
.add(LayerAdapter())
.build()
val type = Types.newParameterizedType(List::class.java, Layer::class.java)
val adapter = moshi.adapter<List<Layer>>(type)
val layers: List<Layer>? = adapter.fromJson("""
[
{"layerType":"SHAPE", "shape":"I am rectangle"},
{"layerType":"TEXT", "text":"I am text"},
{"layerType":"IMAGE", "image":"I am image"}
]
""".trimIndent())
layers?.forEach(::println)
val jsonString: String = adapter.toJson(layers)
println(jsonString)
输出:
ShapeLayer(type=SHAPE, shape=I am rectangle)
TextLayer(type=TEXT, text=I am text)
ImageLayer(type=IMAGE, image=I am image)
[{"layerType":"SHAPE","shape":"I am rectangle"},{"layerType":"TEXT","text":"I am text"},{"image":"I am image","layerType":"IMAGE"}]
编辑:
当您尝试解析包含 Layer
的其他对象时,您可以像往常一样添加适配器。假设您有一个像这样的对象:
data class LayerContainer(val layers: List<Layer>)
测试代码:
val moshi = Moshi.Builder()
.add(LayerAdapter())
.build()
val adapter = moshi.adapter(LayerContainer::class.java)
val layerContainer: LayerContainer? = adapter.fromJson("""
{
"layers": [
{"layerType":"SHAPE", "shape":"I am rectangle"},
{"layerType":"TEXT", "text":"I am text"},
{"layerType":"IMAGE", "image":"I am image"}
]
}
""".trimIndent())
layerContainer?.layers?.forEach(::println)
val jsonString: String = adapter.toJson(layerContainer)
println(jsonString)
@ToJson
方法?下面的答案是正确的。 - Eric Cochran