暂停执行协程以等待回调

素材狗 2022-01-01 13:22:25 文章分类：移动开发问题点击数：1次

文章标签

Suspend Coroutines#39;s execution to wait for callback(暂停执行协程以等待回调)

本文介绍了暂停执行协程以等待回调的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

最近，我在我的项目中应用了Cooutine，看起来一切都很好，但今天我遇到了一个问题[使用Coroutine+Retrofit将文件/图像上传到服务器][1] Cooutine+Retrofit上传文件似乎没有解决方案，所以必须使用回调进行改造。

//Api interface
interface UploadFileApiKotlin {
    @Multipart
    @POST("/uploadFileApi")
    fun uploadFiles(
        @Part listUri: List<MultipartBody.Part>
    ): Call<Response<List<FileResponse>?>>
}
//ViewModel class
serviceScope.launch {
                //Insert into db
                repository.insertNewExtAct()
                //Send data into server.
                val call = RequestHelper.getUpLoadFilesKotlinRequest().uploadFiles(partList)
                call.enqueue(object : Callback<Response<List<FileResponse>?>> {
                    override fun onResponse(
                        call: Call<Response<List<FileResponse>?>>,
                        response: Response<Response<List<FileResponse>?>>
                    ) {
                        TODO("Not yet implemented")
                    }

                    override fun onFailure(
                        call: Call<Response<List<FileResponse>?>>,
                        t: Throwable
                    ) {
                        TODO("Not yet implemented")
                    }
                })
                //Wait for response from server and do logic
            }

我的问题是：如何挂起协程的执行以等待Retrofit的回调？

谢谢你兄弟。 [1]：Upload file/image into server using Coroutine + Retrofit

推荐答案

您可以使用suspendCoroutine或suspendCancellableCoroutine处理回调：

serviceScope.launch {
    //Insert into db
    repository.insertNewExtAct()
    //Send data into server.
    uploadFile()
    //Wait for response from server and do logic
}

suspend fun uploadFile() = suspendCoroutine<Response<List<FileResponse>?>> { continuation ->
    val call = RequestHelper.getUpLoadFilesKotlinRequest().uploadFiles(partList)
    call.enqueue(object : Callback<Response<List<FileResponse>?>> {
        override fun onResponse(
            call: Call<Response<List<FileResponse>?>>,
            response: Response<Response<List<FileResponse>?>>
        ) {
            // Resume coroutine with a value provided by the callback
            continuation.resumeWith(response.data)
        }

        override fun onFailure(
            call: Call<Response<List<FileResponse>?>>,
            t: Throwable
        ) {
            continuation.resumeWithException(t)
        }
    })
}