如何使用改造和 moshi 解析换行符分隔的 JSON？

编程问答 2022-05-15

问题描述

我正在尝试使用改造和 moshi 解析换行符分隔的 json。这是我的 GET 函数：

suspend fun getDeviceValuesNew(@Path("application-id") applicationId: String,@Path("device-id") deviceid: String) 
: Response<List<ValueApiResponse>>

当我尝试运行它时，出现此错误：

 com.squareup.moshi.JsonDataException: Expected BEGIN_ARRAY but was BEGIN_OBJECT at path $

HTTP 调用返回这样的 json：

{
    "result": {
        "end_device_ids": {
            "device_id": "esp32","application_ids": {}
        },"received_at": "2021-03-31T11:33:42.757281753Z","uplink_message": {
            "decoded_payload": {
                "brightness": 0
            },"settings": {
                "data_rate": {}
            },"received_at": "2021-03-31T11:33:42.547285090Z"
        }
    }
}
{
    "result": {
        "end_device_ids": {
            "device_id": "esp32","received_at": "2021-03-31T11:18:17.745921472Z","received_at": "2021-03-31T11:18:17.538276218Z"
        }
    }
}

编辑 #1： 正如您在下面的回答中所看到的，我设法从 API 获得了有效的 JSON 响应，但我仍在努力将这些 JSON 对象解析为 Kotlin 对象列表。 如何让 moshi 将这些换行分隔的 JSON 对象作为列表处理？ 我认为问题在于 moshi 要求将对象包装在数组中才能被识别为列表。我该怎么做？

这是我用于解析的数据类：

@JsonClass(generateAdapter = true)
data class ValueDto(
    @Json(name = "result")
    val result: Result
) {
    @JsonClass(generateAdapter = true)
    data class Result(
        @Json(name = "end_device_ids")
        val enddeviceids: Enddeviceids,@Json(name = "received_at")
        val receivedAt: String,@Json(name = "uplink_message")
        val uplinkMessage: UplinkMessage
    ) {
        @JsonClass(generateAdapter = true)
        data class Enddeviceids(
            @Json(name = "application_ids")
            val applicationIds: ApplicationIds,@Json(name = "device_id")
            val deviceid: String
        ) {
            @JsonClass(generateAdapter = true)
            class ApplicationIds(
            )
        }

        @JsonClass(generateAdapter = true)
        data class UplinkMessage(
            @Json(name = "decoded_payload")
            val decodedPayload: DecodedPayload,@Json(name = "received_at")
            val receivedAt: String,@Json(name = "settings")
            val settings: Settings
        ) {
            @JsonClass(generateAdapter = true)
            data class DecodedPayload(
                @Json(name = "brightness")
                val brightness: Int
            )
            @JsonClass(generateAdapter = true)
            data class Settings(
                @Json(name = "data_rate")
                val datarate: Datarate
            ) {
                @JsonClass(generateAdapter = true)
                class Datarate(
                )
            }
        }
    }
}

解决方法

@tyczj 是对的，这不是有效的 ndjson，因为在 ndjson 中换行符只出现在每个单独的 json 文本之后。解决方案是使用 HTTP 请求发送 Accept: text/event-stream，现在我得到了一个有效的 ndjson 响应，如下所示：

{"result":{"end_device_ids":{"device_id":"esp32-bh1750","application_ids":{}},"received_at":"2021-04-24T10:19:04.021238048Z","uplink_message":{"decoded_payload":{"brightness":0},"settings":{"data_rate":{}},"received_at":"2021-04-24T10:19:03.809173924Z"}}}

{"result":{"end_device_ids":{"device_id":"esp32-bh1750","received_at":"2021-04-24T10:25:22.260712161Z","uplink_message":{"decoded_payload":{"brightness":119},"received_at":"2021-04-24T10:25:22.046086937Z"}}}

{"result":{"end_device_ids":{"device_id":"esp32-bh1750","received_at":"2021-04-24T10:18:58.438947740Z","received_at":"2021-04-24T10:18:58.228671174Z"}}}

{"result":{"end_device_ids":{"device_id":"esp32-bh1750","received_at":"2021-04-24T10:21:10.102303310Z","uplink_message":{"decoded_payload":{"brightness":106},"received_at":"2021-04-24T10:21:09.893217735Z"}}}

{"result":{"end_device_ids":{"device_id":"esp32-bh1750","received_at":"2021-04-24T10:23:16.177064041Z","uplink_message":{"decoded_payload":{"brightness":108},"received_at":"2021-04-24T10:23:15.967959055Z"}}}

{"result":{"end_device_ids":{"device_id":"esp32-bh1750","received_at":"2021-04-24T10:27:28.334312076Z","uplink_message":{"decoded_payload":{"brightness":117},"received_at":"2021-04-24T10:27:28.126104222Z"}}}

{"result":{"end_device_ids":{"device_id":"esp32-bh1750","received_at":"2021-04-24T10:29:34.400253264Z","uplink_message":{"decoded_payload":{"brightness":99},"received_at":"2021-04-24T10:29:34.190980301Z"}}}

{"result":{"end_device_ids":{"device_id":"esp32-bh1750","received_at":"2021-04-24T10:31:40.481766225Z","uplink_message":{"decoded_payload":{"brightness":118},"received_at":"2021-04-24T10:31:40.270452429Z"}}}

{"result":{"end_device_ids":{"device_id":"esp32-bh1750","received_at":"2021-04-24T10:33:46.567235913Z","uplink_message":{"decoded_payload":{"brightness":114},"received_at":"2021-04-24T10:33:46.357373037Z"}}}

{"result":{"end_device_ids":{"device_id":"esp32-bh1750","received_at":"2021-04-24T10:35:52.737386496Z","uplink_message":{"decoded_payload":{"brightness":121},"received_at":"2021-04-24T10:35:52.426583804Z"}}}

我已经通过改造注释添加了标题： @Headers("Accept: text/event-stream ")

androidandroidjsonmoshindjsonretrofit