改造问题：尽管设置正确，但“无法连接到端点”

Question

我正在开发一个 Android 应用程序，它使用 Retrofit 来调用 Render 上托管的模型。端点应该接受带有州和年份的请求，并返回包含预测降雨数据的 JSON 对象。

以下是典型 JSON 响应的示例：

{
  "predicted_rainfall": {
    "APR": 124.20799999999997,
    "AUG": 358.282,
    "DEC": 68.95199999999994,
    "FEB": 27.997999999999966,
    "JAN": 18.76000000000003,
    "JUL": 911.7139999999999,
    "JUN": 666.5559999999996,
    "MAR": 44.099999999999994,
    "MAY": 177.19000000000023,
    "NOV": 259.6499999999997,
    "OCT": 305.5620000000003,
    "SEP": 296.3400000000001
  },
  "state": "KERALA",
  "year": "1901"
}

终点是

"https://rainfallpredictionmodel.onrender.com/predict/rainfall"

。

我创建了一个 Retrofit 设置来调用此端点，但它总是失败，并显示错误“连接失败”。最初，我使用 Volley 但遇到了同样的问题，促使改用 Retrofit。

这是改造设置的代码：

import retrofit2.Retrofit
import retrofit2.converter.gson.GsonConverterFactory
import retrofit2.Call
import retrofit2.Callback
import retrofit2.Response
import android.os.Bundle
import android.util.Log
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Button
import android.widget.EditText
import android.widget.Toast
import com.google.android.material.bottomsheet.BottomSheetDialogFragment
import okhttp3.OkHttpClient
import org.json.JSONObject
import java.util.concurrent.TimeUnit

class BottomSheetRainfall : BottomSheetDialogFragment() {
    private val TAG = "RainfallFragment"

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        return inflater.inflate(R.layout.fragment_bottom_sheet_rainfall, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        val submitButton = view.findViewById<Button>(R.id.submit_rainfall)
        val stateNameEditText = view.findViewById<EditText>(R.id.state_name)
        val yearEditText = view.findViewById<EditText>(R.id.year)

        val okHttpClient = OkHttpClient.Builder()
            .connectTimeout(30, TimeUnit.SECONDS)  // Increased connection timeout
            .readTimeout(30, TimeUnit.SECONDS)     // Increased read timeout
            .writeTimeout(30, TimeUnit.SECONDS)    // Increased write timeout
            .build()

        val retrofit = Retrofit.Builder()
            .baseUrl("https://rainfallpredictionmodel.onrender.com/")
            .client(okHttpClient)
            .addConverterFactory(GsonConverterFactory.create())
            .build()

        val rainfallService = retrofit.create(RainfallService::class.java)

        submitButton.setOnClickListener {
            val state = stateNameEditText.text.toString().uppercase()
            val year = yearEditText.text.toString()

            if (state.isNotEmpty() && year isNotEmpty()) {
                val request = RainfallRequest(state, year)

                rainfallService.predictRainfall(request).enqueue(object : Callback<RainfallResponse> {
                    override fun onResponse(
                        call: Call<RainfallResponse>,
                        response: Response<RainfallResponse>
                    ) {
                        if (response.isSuccessful) {
                            val predictedRainfall = response.body()?.predicted_rainfall ?: emptyMap()
                            Toast.makeText(
                                requireContext(),
                                "Rainfall data retrieved successfully",
                                Toast.LENGTH_SHORT
                            ).show()
                        } else {
                            Toast.makeText(
                                requireContext(),
                                "Error: ${response.message()}",
                                Toast.LENGTH_SHORT
                            ).show()
                        }
                    }

                    override fun onFailure(call: Call<RainfallResponse>, t: Throwable) {
                        Log.e(TAG, "Error during API call", t)
                        Toast.makeText(requireContext(), "Error: ${t.localizedMessage}", Toast.LENGTH_SHORT).show()
                    }
                })
            } else {
                Toast.makeText(requireContext(), "Please enter both state and year", Toast.LENGTH_SHORT).show()
            }
        }
    }
}

RainfallService

界面如下所示：

package com.example.safenet

import retrofit2.Call
import retrofit2.http.Body
import retrofit2.http.POST

interface RainfallService {
    @POST("predict/rainfall")
    fun predictRainfall(@Body request: RainfallRequest): Call<RainfallResponse>
}

这是请求和响应的数据类：

com.example.safenet 包

数据类 RainfallRequest(val 状态: String, val 年份: String)

数据类 RainfallResponse(val Predicted_rainfall: Map)

尽管如此设置，我仍然收到以下错误：“无法连接到

https://rainfallpredictionmodel.onrender.com/predict/rainfall

。” Retrofit 和 Volley 都会出现同样的错误。对于解决此问题的任何建议，我将不胜感激。

Answer 1

你添加了吗

<uses-permission android:name="android.permission.INTERNET" />

在 AndroidManifest 中？