NetworkOnMainThreadException 即使订阅了 schedulers.io()答案

【问题标题】：NetworkOnMainThreadException even after subscribing to schedulers.io()NetworkOnMainThreadException 即使订阅了 schedulers.io()
【发布时间】：2019-08-15 20:16:58
【问题描述】：

我尝试练习我的技能，并尝试使用 RX java 模拟网络。

但是当我尝试执行我的代码时，我得到了NetworkOnMainThreadException，尽管我使用了Schedulers.io() 线程。

我想将代码分成三个方法，但它不起作用。我已经用.fromCallable{} 替换了所有.just()，但它仍然无法正常工作

这是我的代码：

fun String.post(authorization: String, params: HashMap<String, String>): Single<out Response> {
    try {
        val url = URL(this)
        val connection = url.openConnection() as HttpsURLConnection
        connection.apply {
            requestMethod = "POST"
            addRequestProperty("Authorization", authorization.sha1())
            addRequestProperty("Content-Type", "application/x-www-form-urlencoded")
            doOutput = true
            DataOutputStream(connection.outputStream).use {
                it.write(params.toUrlEncoded().toByteArray())
            }

            val single = when (connection.responseCode) {
                200, 201 -> {
                    val body = connection.inputStream.bufferedReader().use(BufferedReader::readText)
                    Single.fromCallable { DataResponse(HttpsURLConnection.HTTP_OK, body) }
                }
                else -> {
                    val message = connection.errorStream.bufferedReader().use(BufferedReader::readText)
                    Single.fromCallable { ErrorResponse(connection.responseCode, message) }
                }
            }
            connection.disconnect()
            return single
        }
    } catch (e: Exception) {
        e.printStackTrace()
        return Single.fromCallable { ErrorResponse(500, e.message.toString()) }
    }
} 

fun downloadImage(authorization: String, params: HashMap<String, String>): Single<Any> {
        return (BuildConfig.BASE_URL + IMAGE_URL).post(authorization, params).flatMap {
            when (it) {
                is DataResponse -> {
                    val json = JSONObject(it.body)
                    if (json.has("image")) {
                        return@flatMap Single.fromCallable { ImageData(json.getString("image")) }
                    } else {
                        return@flatMap Single.error<HttpException>(HttpException(-1, ""))
                    }
                }
                is ErrorResponse -> {
                    return@flatMap Single.error<HttpException>(HttpException(it.code, it.message))
                }
                else -> {
                    return@flatMap Single.error<HttpException>(HttpException(-1, ""))
                }
            }
        }
    } 

repository.downloadImage(password, hashMapOf("username" to login)).subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread()).subscribeBy({
                it.printStackTrace()
            }, {
                _imageData.postValue(it as ImageData)
            })

【问题讨论】：

标签： android kotlin rx-java2 kotlin-android-extensions

【解决方案1】：

好的，这很奇怪，但我设法通过从 String.post() 函数中删除 Single() 包装类来解决它。所以工作代码：

fun String.post(authorization: String, params: HashMap<String, String>): Response {
    try {
        val url = URL(this)
        val connection = url.openConnection() as HttpsURLConnection
        connection.apply {
            requestMethod = "POST"
            addRequestProperty("Authorization", authorization.sha1())
            addRequestProperty("Content-Type", "application/x-www-form-urlencoded")
            doOutput = true
            DataOutputStream(connection.outputStream).use {
                it.write(params.toUrlEncoded().toByteArray())
            }

            val response = when (connection.responseCode) {
                200, 201 -> {
                    val body = connection.inputStream.bufferedReader().use(BufferedReader::readText)
                    DataResponse(HttpsURLConnection.HTTP_OK, body)
                }
                else -> {
                    val message = connection.errorStream.bufferedReader().use(BufferedReader::readText)
                     ErrorResponse(connection.responseCode, message)
                }
            }
            connection.disconnect()
            return response
        }
    } catch (e: Exception) {
        e.printStackTrace()
        return ErrorResponse(500, e.message.toString())
    }
} 


fun downloadImage(authorization: String, params: HashMap<String, String>): Single<Any> {
        return Single.fromCallable { (BuildConfig.BASE_URL + IMAGE_URL).post(authorization, params) }.flatMap {
            when (it) {
                is DataResponse -> {
                    val json = JSONObject(it.body)
                    if (json.has("image")) {
                        return@flatMap Single.fromCallable { ImageData(json.getString("image")) }
                    } else {
                        return@flatMap Single.error<HttpException>(HttpException(-1, ""))
                    }
                }
                is ErrorResponse -> {
                    return@flatMap Single.error<HttpException>(HttpException(it.code, it.message))
                }
                else -> {
                    return@flatMap Single.error<HttpException>(HttpException(-1, ""))
                }
            }
        }
    }

【讨论】：