Question

我对科特林和观察员是陌生的。我正在使用Retrofit进行API调用。我的API调用以空数组形式返回响应。我无法弄清楚如何使用观察者来处理它。拜托，任何人，请帮帮我。预先感谢

API调用方法：

@GET("transaction/get")
fun getTransactions(@Query("date") date: String?, @Query("user_id") user_id: Int, @Query("account_id") account_id: Int?): Observable<TransactionModel>

连接类

public class ApiServiceNetwork private constructor()//hide the public constructor
    : Interceptor {
    @Throws(IOException::class)
    override fun intercept(chain: Interceptor.Chain): Response {
        val request = chain.request()
        val builder: Request.Builder
        builder = request.newBuilder()
        val request1 = builder.build()
        //Here we can modify request1 and response if we want (like adding header or auth)
        val response = chain.proceed(request1)

        return response
    }

    private val logger: okhttp3.logging.HttpLoggingInterceptor
        get() {
            val logging = okhttp3.logging.HttpLoggingInterceptor()
            logging.level = okhttp3.logging.HttpLoggingInterceptor.Level.HEADERS
            logging.level = okhttp3.logging.HttpLoggingInterceptor.Level.BASIC
            logging.level = okhttp3.logging.HttpLoggingInterceptor.Level.BODY
            return logging
        }

    fun getNetworkService(): WebServiceInterface {
        return createRetrofitInstance(EndPoint.SERVER_ENDPOINT).create(WebServiceInterface::class.java)
    }

    private fun createRetrofitInstance(url: String): Retrofit {
        val okHttpClient = OkHttpClient.Builder()
        okHttpClient.addInterceptor(this)
        okHttpClient.addNetworkInterceptor(StethoInterceptor())
        okHttpClient.addInterceptor(logger)
        retrofit.baseUrl(url)
                .addConverterFactory(GsonConverterFactory.create(GsonBuilder().serializeNulls().setLenient().create()))
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .client(okHttpClient.connectTimeout(60,
                        TimeUnit.SECONDS).writeTimeout(60,
                        TimeUnit.SECONDS).readTimeout(60,
                        TimeUnit.SECONDS).build())
        return retrofit.build()

    }

    companion object {
        private val retrofit = Retrofit.Builder()

        fun getInstance(): ApiServiceNetwork {
            return ApiServiceNetwork()
        }
    }

我的活动中的函数调用：

mApiServiceNetwork.getNetworkService().getTransactions(date, user_id, account_id)
                .subscribeOn(Schedulers.io())
                .unsubscribeOn(Schedulers.computation())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe({

                    this.transaction = it

                    this.expenseDataAdapter.setExpenses(it.expenses!!)
                    this.recyclerView.adapter = expenseDataAdapter

                    this.textViewSpendingAccount.text = it.account!!.title

                    this.textViewSpendingExpense.text = it.total_expense.toString()
                    this.textViewSpendingIncome.text = it.total_income.toString()
                    this.textViewSpendingBalance.text = it.balance.toString()

                    Log.d("__EXPENSE", it.total_expense.toString())

                }, {
                    Toast.makeText(this.requireContext(), it.message, Toast.LENGTH_LONG).show()
                }, {
                    this.expenseDataAdapter.notifyDataSetChanged()
                })

Answer 1

如果您从不关心响应中的数据（即，如果它始终是一个空数组），则可以使用Completable而不是Observable<TransactionModel>。查看您的代码，情况似乎并非如此。
如果响应有时包含数据，有时返回空数组，则可以使用自定义Converter.Factory截获GSON转换器工厂之前的调用，并以所需的方式格式化返回值。这将空响应限制为您可以接受的呼叫。

带有伪代码的示例：

class EmptyArrayConverterFactory : Converter.Factory() {

    override fun responseBodyConverter(type: Type, annotations: Array<Annotation>, retrofit: Retrofit): Converter<ResponseBody, *>? {
        val delegate = retrofit.nextResponseBodyConverter<Any>(this, type, annotations)
        return Converter<ResponseBody, Any> { body ->
            var bodyString = body.String()
            if (bodyString == "{[]}") { // Or whatever the empty array is returned as
                bodyString = //Convert body string to empty/error TransactionModel JSON
            }
            delegate.convert(bodyString) 
        }
    }

}

另一种选择，如果响应有时包含数据而有时没有数据，则可以返回Observable<ResponseBody>而不是Observable<TransactionModel>，然后在subscribe()函数中自行解析响应，同时考虑到空数组的可能性。考虑到情况和我对您情况的有限了解，我认为这将是最灵活的选择。

这看起来像这样：

API定义： @GET（“交易/获取”） fun getTransactions（@Query（“ date”）date：字符串？，@Query（“ user_id”）user_id：Int，@Query（“ account_id”）account_id：Int？）：可观察

用法：

mApiServiceNetwork.getNetworkService().getTransactions(date, user_id, account_id)
            .subscribeOn(Schedulers.io())
            .unsubscribeOn(Schedulers.computation())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe({ responseBody ->

                if(responseBody.string() == "{[]}"){
                    // handle the empty list however you want
                }
                else{ 
                    // Handle the response normally
                    this.transaction = it

                    this.expenseDataAdapter.setExpenses(it.expenses!!)
                    this.recyclerView.adapter = expenseDataAdapter

                    this.textViewSpendingAccount.text = it.account!!.title

                    this.textViewSpendingExpense.text = it.total_expense.toString()
                    this.textViewSpendingIncome.text = it.total_income.toString()
                    this.textViewSpendingBalance.text = it.balance.toString()

                    Log.d("__EXPENSE", it.total_expense.toString())
                }

            }, {
                Toast.makeText(this.requireContext(), it.message, Toast.LENGTH_LONG).show()
            }, {
                this.expenseDataAdapter.notifyDataSetChanged()
            })

如何在Kotlin中通过改造来处理HTTP响应中的空数组

1 个答案: