我正在尝试使用 Retrofit2 从网站获取数据到我的 Android Studios 代码，但不知何故它不起作用

Question

我想从这个网站获取数据： http://ries.world:32170/rest/getDateTime 。有 4 个信息 Local、utc、message 和 code。我试图获取它们，然后在模拟器中显示它们，但不知何故它没有显示信息，我真的不知道为什么。而且程序根本没有显示任何错误。

这就是MainActivity.kt

package com.example.test48

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.TextView
import retrofit2.Call
import retrofit2.Callback
import retrofit2.Response
import retrofit2.Retrofit
import retrofit2.converter.gson.GsonConverterFactory

class MainActivity : AppCompatActivity() {

    private lateinit var local: TextView
    private lateinit var utc: TextView
    private lateinit var message: TextView
    private lateinit var code: TextView

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        local = findViewById(R.id.local)
        utc = findViewById(R.id.utc)
        message = findViewById(R.id.message)
        code = findViewById(R.id.code)

        val retrofit = Retrofit.Builder()
            .baseUrl("http://ries.world:32170/")
            .addConverterFactory(GsonConverterFactory.create())
            .build()

        val apiService = retrofit.create(ApiService::class.java)

        val call: Call<ApiResponse> = apiService.getData()

        call.enqueue(object : Callback<ApiResponse> {
            override fun onResponse(call: Call<ApiResponse>, response: Response<ApiResponse>) {
                if (response.isSuccessful) {
                    val apiResponse: ApiResponse? = response.body()

                    local.text = getString(R.string.local_placeholder, apiResponse?.local.orEmpty())
                    utc.text = getString(R.string.utc_placeholder, apiResponse?.local.orEmpty())
                    message.text = getString(R.string.message_placeholder, apiResponse?.local.orEmpty())
                    code.text = getString(R.string.code_placeholder, apiResponse?.local.orEmpty())

                }
            }

            override fun onFailure(call: Call<ApiResponse>, t: Throwable) {
                t.printStackTrace()
            }
        })
    }
}

这就是ApiService

package com.example.test48

import retrofit2.Call
import retrofit2.http.GET

interface ApiService {
    @GET("rest/getDateTime")
    fun getData(): Call<ApiResponse>
}

这就是 ApiResponse

package com.example.test48

data class ApiResponse(
    val local: String?,
    val utc: String?,
    val message: String?,
    val code: String?
)

这就是activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/local"
        android:layout_width="407dp"
        android:layout_height="75dp"
        android:layout_marginStart="131dp"
        android:layout_marginTop="77dp"
        android:layout_marginEnd="131dp"
        android:text="@string/local_label"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/utc"
        android:layout_width="412dp"
        android:layout_height="67dp"
        android:layout_marginStart="131dp"
        android:layout_marginTop="200dp"
        android:layout_marginEnd="131dp"
        android:text="@string/utc_label"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/message"
        android:layout_width="408dp"
        android:layout_height="66dp"
        android:layout_marginStart="131dp"
        android:layout_marginTop="330dp"
        android:layout_marginEnd="131dp"
        android:text="@string/message_label"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/code"
        android:layout_width="405dp"
        android:layout_height="56dp"
        android:layout_marginStart="131dp"
        android:layout_marginTop="460dp"
        android:layout_marginEnd="131dp"
        android:text="@string/code_label"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

这就是build.graddle.kts

plugins {
    id("com.android.application")
    id("org.jetbrains.kotlin.android")
}

android {
    namespace = "com.example.test48"
    compileSdk = 34

    defaultConfig {
        applicationId = "com.example.test48"
        minSdk = 28
        targetSdk = 34
        versionCode = 1
        versionName = "1.0"

        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            isMinifyEnabled = false
            proguardFiles(
                getDefaultProguardFile("proguard-android-optimize.txt"),
                "proguard-rules.pro"
            )
        }
    }
    compileOptions {
        sourceCompatibility = JavaVersion.VERSION_1_8
        targetCompatibility = JavaVersion.VERSION_1_8
    }
    kotlinOptions {
        jvmTarget = "1.8"
    }
}

dependencies {

    implementation("androidx.core:core-ktx:1.12.0")
    implementation("androidx.appcompat:appcompat:1.6.1")
    implementation("com.google.android.material:material:1.11.0")
    implementation("androidx.constraintlayout:constraintlayout:2.1.4")
    testImplementation("junit:junit:4.13.2")
    androidTestImplementation("androidx.test.ext:junit:1.1.5")
    androidTestImplementation("androidx.test.espresso:espresso-core:3.5.1")
    implementation("com.squareup.retrofit2:retrofit:2.9.0")
    implementation("com.squareup.retrofit2:converter-gson:2.9.0")
}

这在 AndroidManifest.xml 中

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

最后，这是 Strings.xml

<resources>
    <string name="app_name">Test48</string>
    <string name="local_placeholder">Local: %1$s</string>
    <string name="utc_placeholder">Utc: %1$s</string>
    <string name="message_placeholder">Message: %1$s</string>
    <string name="code_placeholder">Code: %1$s</string>
    <string name="local_label">Local: </string>
    <string name="utc_label">Utc: </string>
    <string name="message_label">Message: </string>
    <string name="code_label">Code: </string>
</resources>

我尝试从上述网站获取数据，然后将其显示在 Android Studios 模拟器上。然而它并没有按计划进行，我看不到数据，我完全不知道为什么。

Answer 1

尝试在 Manifest

android:usesCleartextTraffic

和/或

true

中设置

NetworkSecurityPolicy.getInstance().isCleartextTrafficPermitted()

，它应该返回 false