kotlinx.serialization.SerializationException：找不到类“MultiPartFormDataContent”的序列化程序

Posted 2023-04-15

【中文标题】kotlinx.serialization.SerializationException：找不到类“MultiPartFormDataContent”的序列化程序

【英文标题】：kotlinx.serialization.SerializationException: Serializer for class 'MultiPartFormDataContent' is not found

【发布时间】：2021-04-25 18:56:53

【问题描述】：

我正在尝试上传多个文件。

val ktorVersion = "1.5.0"
val serializationVersion = "1.0.1"

我就是这样做的：

  override suspend fun uploadFiles(
    binaryFiles: Map<String,ByteArray>
  ): BaseResponse<List<String>> 
    return client.submitForm 

      url(fileUploadUrl)
      method = HttpMethod.Post
      body = MultiPartFormDataContent(
        formData 
          headers
            append("Content-Type", "application/json")
            append("Authorization", "Bearer $token")
          
          binaryFiles.entries.forEach 
            append(
              key = "files",
              value = it.value,
              headers = Headers.build 
                append(HttpHeaders.ContentDisposition, "filename=$it.key")
              
            )
          
        
      )
    
  

但是会抛出异常

kotlinx.serialization.SerializationException: Serializer for class 'MultiPartFormDataContent' is not found.
Mark the class as @Serializable or provide the serializer explicitly.
    at kotlinx.serialization.internal.Platform_commonKt.serializerNotRegistered(Platform.common.kt:91)
    at kotlinx.serialization.SerializersKt__SerializersKt.serializer(Serializers.kt:130)
    at kotlinx.serialization.SerializersKt.serializer(Unknown Source)
    at io.ktor.client.features.json.serializer.KotlinxSerializerKt.buildSerializer(KotlinxSerializer.kt:82)
    at io.ktor.client.features.json.serializer.KotlinxSerializerKt.access$buildSerializer(KotlinxSerializer.kt:1)
    at io.ktor.client.features.json.serializer.KotlinxSerializer.writeContent$ktor_client_serialization(KotlinxSe
    at io.ktor.client.features.json.serializer.KotlinxSerializer.write(KotlinxSerializer.kt:26)
    at io.ktor.client.features.json.JsonFeature$Feature$install$1.invokeSuspend(JsonFeature.kt:150)
    at io.ktor.client.features.json.JsonFeature$Feature$install$1.invoke(JsonFeature.kt)
    at io.ktor.util.pipeline.SuspendFunctionGun.loop(SuspendFunctionGun.kt:243)
    at io.ktor.util.pipeline.SuspendFunctionGun.proceed(SuspendFunctionGun.kt:113)
    at io.ktor.util.pipeline.SuspendFunctionGun.proceedWith(SuspendFunctionGun.kt:123)
    at io.ktor.client.features.HttpCallValidator$Companion$install$1.invokeSuspend(HttpCallValidator.kt:106)
    at io.ktor.client.features.HttpCallValidator$Companion$install$1.invoke(HttpCallValidator.kt)
    at io.ktor.util.pipeline.SuspendFunctionGun.loop(SuspendFunctionGun.kt:243)
    at io.ktor.util.pipeline.SuspendFunctionGun.proceed(SuspendFunctionGun.kt:113)
    at io.ktor.client.features.HttpRequestLifecycle$Feature$install$1.invokeSuspend(HttpRequestLifecycle.kt:37)
    at io.ktor.client.features.HttpRequestLifecycle$Feature$install$1.invoke(HttpRequestLifecycle.kt)
    at io.ktor.util.pipeline.SuspendFunctionGun.loop(SuspendFunctionGun.kt:243)
    at io.ktor.util.pipeline.SuspendFunctionGun.proceed(SuspendFunctionGun.kt:113)
    at io.ktor.util.pipeline.SuspendFunctionGun.execute(SuspendFunctionGun.kt:133)
    at io.ktor.util.pipeline.Pipeline.execute(Pipeline.kt:79)
    at io.ktor.client.HttpClient.execute(HttpClient.kt:187)
    at io.ktor.client.statement.HttpStatement.executeUnsafe(HttpStatement.kt:104)
    at com.example.package.core.data.network.services.upload.FileUploadApiImpl.uploadFiles(FileUploadApi.kt:99)

我也尝试过，但遇到了同样的问题：

  suspend fun uploadFilesTest(
    binaryFiles: Map<String,ByteArray>
  ): BaseResponse<List<String>> 
    return client.post(fileUploadUrl) 
      headers 
        append("Content-Type", ContentType.Application.Json)
        append("Authorization", "Bearer $token")
      
      body = MultiPartFormDataContent(
        formData 
          binaryFiles.entries.forEach 
            this.appendInput(
              key = "files",
              size = it.value.size.toLong(),
              headers = Headers.build 
                append(HttpHeaders.ContentDisposition, "filename=$it.key")
              ,
            ) buildPacket  writeFully(it.value) 
          
        
      )
    
  

【参考方案1】：

看看你上次说你有同样问题的sn-p，你好像在这样的标题中指定内容类型

append("Content-Type", ContentType.Application.Json)

但您还希望它是多部分的，方法是将 body 设置为 MultiPartFormDataContent，它还需要定义为标头 content-type:multipart/form-data; ...，因此可能是此冲突导致了问题。

我实际上只是在我的代码中自己尝试过，这对我来说似乎是个问题。

【讨论】：

从标题中删除内容类型解决了问题

【参考方案2】：

我为 android 做了这个，但它也可能适用于 ktor。首先，将此行添加到构建项目 gradle 中的 dependencies 中：

classpath "org.jetbrains.kotlin:kotlin-serialization:1.5.21"

将这些也添加到构建应用程序 gradle：

plugins 
    ...
    id 'kotlinx-serialization'

dependencies 
    ...
    implementation 'org.jetbrains.kotlinx:kotlinx-serialization-json:1.2.2'