带有改造的协程 Kotlin Android

Question

class Service{
    interface  RedditApi {
        @GET("/top.json")
        fun getTop(@Query("after") after: String,
                   @Query("limit") limit: String)
                : Deferred<Response<News>>;
    }
}
 val okHttpClient = OkHttpClient.Builder()
            .readTimeout(40, TimeUnit.SECONDS)
            .addInterceptor { chain ->
                val ongoing = chain.request().newBuilder()
                ongoing.addHeader("Cache-Control", "no-cache")
                ongoing.addHeader("User-Agent", System.getProperty("http.agent"))
                //ongoing.addHeader("Authorization", val.trim());
                chain.proceed(ongoing.build())
            }
            .connectTimeout(40, TimeUnit.SECONDS)
            .build()
        val retrofit = Retrofit.Builder()
            .baseUrl( "/rest/s1/mobile/")
            .addConverterFactory(GsonConverterFactory.create())
            .addCallAdapterFactory(CoroutineCallAdapterFactory())
            .client(okHttpClient)
            .build()
        redditApi = retrofit.create(Service.RedditApi::class.java)

好吧，我知道了，我正在尝试对 Coroutine 进行改造。我去我的活动并像下面那样实现它。我得到错误 dispatchers.main unresolved reference main。我使用的是 kotlin 1.3.21。另外我的另一个问题是，如果用户单击活动，我该如何取消协程操作？就像在 Java 中，我曾经用改造来做 call.cancel()。它取消了调用。

class MainActivity : AppCompatActivity(), Fightable {
        override fun onCreate(savedInstanceState: Bundle?) {
            super.onCreate(savedInstanceState)
            setContentView(R.layout.activity_main)


            CoroutineScope(Dispatchers.IO).launch {
                val request = App.redditApi.getTop("after", "limit")
                withContext(Dispatchers.Main) {
                    try {
                        val response = request.await()
                        if (response.isSuccessful) {
                            val news: News? = response.body()
                            //Do something with response e.g show to the UI.
                        } else {
                        }
                    } catch (e: HttpException) {
                    } catch (e: Throwable) {
                    }
                }
            }}}

Answer 1

您需要创建协程上下文的单个实例，并为其定义一个作业。 val job = Job() val coroutineScope = CoroutineContext(Dispatchers.Main+job)

并使用声明的范围开始工作，当您想取消工作时，您只需调用job.cancel() 即可取消所有当前和即将进行的工作。