Android Studio改版调用失败

Question

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

implementation 'com.squareup.retrofit2:retrofit:2.5.0'
implementation 'com.squareup.retrofit2:converter-gson:2.5.0'

import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;

public class TimeForIstanbul {
    @SerializedName("day_of_week")
    @Expose
    public Integer dayOfWeek;
    @SerializedName("utc_datetime")
    @Expose
    public String utcDatetime;
    @SerializedName("week_number")
    @Expose
    public Integer weekNumber;

    public Integer getDayOfWeek() {
        return dayOfWeek;
    }

    public void setDayOfWeek(Integer dayOfWeek) {
        this.dayOfWeek = dayOfWeek;
    }

    public String getUtcDatetime() {
        return utcDatetime;
    }

    public void setUtcDatetime(String utcDatetime) {
        this.utcDatetime = utcDatetime;
    }

    public Integer getWeekNumber() {
        return weekNumber;
    }

    public void setWeekNumber(Integer weekNumber) {
        this.weekNumber = weekNumber;
    }
}

import retrofit2.Call;
import retrofit2.http.GET;

public interface ApiService {
    @GET("Europe/Istanbul")
    Call<TimeForIstanbul> getTime();
}

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;

import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;
import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;

public class MainActivity extends AppCompatActivity {

    private Retrofit retrofit;
    private ApiService apiService;
    private String BASE_URL = "http://worldtimeapi.org/api/timezone/";
    private Call<TimeForIstanbul> timeForIstanbulCall;
    private TimeForIstanbul timeForIstanbul;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        setRetrofitSettings();
    }
    private void setRetrofitSettings(){
        retrofit = new Retrofit.Builder()
                .baseUrl(BASE_URL)
                .addConverterFactory(GsonConverterFactory.create())
                .build();
        apiService = retrofit.create(ApiService.class);
        timeForIstanbulCall = apiService.getTime();
        timeForIstanbulCall.enqueue(new Callback<TimeForIstanbul>() {
            @Override
            public void onResponse(Call<TimeForIstanbul> call, Response<TimeForIstanbul> response) {
                if(response.isSuccessful()){
                    timeForIstanbul = response.body();
                    System.out.println(timeForIstanbul.getDayOfWeek());
                }
            }

            @Override
            public void onFailure(Call<TimeForIstanbul> call, Throwable t) {
                System.out.println("Error is ");
                System.out.println(t.toString());
            }
        });
    }
}

I/System.out: Error is 
    java.net.UnknownServiceException: CLEARTEXT communication to worldtimeapi.org not permitted by network security policy

在logcat上，所以它转到onfailure。我错过了什么？这里怎么了？这个例子的资源是这个视频

Answer 1

您必须将https与该API一起使用。变化：

private String BASE_URL = "http://worldtimeapi.org/api/timezone/";

到

private String BASE_URL = "https://worldtimeapi.org/api/timezone/";

如果您希望与api进行明文通信，您必须遵循Android文档中的步骤