kotlin - 改造成功后，协程问题将数据插入房间数据库

Question

我正在使用Retrofit从API服务器获取新闻记录，如果成功，则它将使用insertAll作为以下代码将数据写入 session 室数据库，但是此代码会产生如下错误
无法访问主线程上的数据库，因为它可能长时间锁定用户界面

我尝试将Coroutine与withContext(Dispatchers.IO)一起使用，但我认为这是不正确的，谢谢您的任何帮助

suspend fun refreshNews(queryString: String="", page: Int = 1) {
  withContext(Dispatchers.IO) {
    RetrofitClient.instance.getAllNews(buatObjectNewsQuery(queryString), page)
        .enqueue(object : Callback<NewsGetAllResponse> {
            override fun onFailure(call: Call<NewsGetAllResponse>, t: Throwable) {
                Timber.tag(TAG).i("sorry network error")
            }

            override fun onResponse(
                call: Call<NewsGetAllResponse>,
                response: Response<NewsGetAllResponse>
            ) {
                val newslist = response.body()?.asDatabaseModel()
                if (newslist != null) {
                    database.databaseNewsDao.insertAll(*newslist)
                    Timber.tag(TAG).i("dalam refresh jumlah data ${newslist.size}")
                }
            }


        })

  }
}

Answer 1

您的代码应看起来像这样。用suspendCoroutine隔离回调代码，以便withContext(Dispatchers.IO)之类的东西可以按预期工作。

suspend fun refreshNews(queryString: String="", page: Int = 1) {
    val call = RetrofitClient.instance.getAllNews(buatObjectNewsQuery(queryString), page)
    val response = suspendCoroutine { cont ->
        call.enqueue(object : Callback<NewsGetAllResponse> {
            override fun onFailure(call: Call<NewsGetAllResponse>, t: Throwable) {
                cont.resumeWithException(t)
            }

            override fun onResponse(
                call: Call<NewsGetAllResponse>,
                response: Response<NewsGetAllResponse>
            ) {
                const.resume(response)
            }
        })
    }

    val newslist = response.body()?.asDatabaseModel()
    if (newslist != null) {
        withContext(Dispatchers.IO) {
            database.databaseNewsDao.insertAll(*newslist)
            Timber.tag(TAG).i("dalam refresh jumlah data ${newslist.size}")
        }
    }
}

编辑:

理想情况下，您想为此创建扩展功能，因此阅读起来看起来并不那么吓人。

suspend fun <T> Call<T>.awaitResponse(): Response<T> {
    return suspendCancellableCoroutine { continuation ->
        continuation.invokeOnCancellation {
            cancel()
        }
        enqueue(object : Callback<T> {
            override fun onResponse(call: Call<T>, response: Response<T>) {
                continuation.resume(response)
            }

            override fun onFailure(call: Call<T>, t: Throwable) {
                continuation.resumeWithException(t)
            }
        })
    }
}

suspend fun refreshNews(queryString: String="", page: Int = 1) {
    val call = RetrofitClient.instance.getAllNews(buatObjectNewsQuery(queryString), page)
    val response = call.awaitResponse()

    val newslist = response.body()?.asDatabaseModel()
    if (newslist != null) {
        withContext(Dispatchers.IO) {
            database.databaseNewsDao.insertAll(*newslist)
            Timber.tag(TAG).i("dalam refresh jumlah data ${newslist.size}")
        }
    }
}