响应：logcat 中的 null

问：

我正在尝试获取Nextcloud服务器中的所有用户ID。我有这个 Login.java。我可以在 Web 应用程序中正常调用 getNCUserIds，但在 Android 应用程序中出现错误。我检查logcat，这里是：

响应：null

响应不应为 null，因为至少有一个帐户是 admin。我试图记录状态代码，但它没有显示。 这是服务器端使用 PHP 的 API：

public function getNCUserIds() {
    $users = \OC::$server->getUserManager()->search('');
    $userIds = array_map(function($user) {
        return $user->getUID();
    }, $users);
    return new JSONResponse(['users' => $userIds]);
}

这是我存储 JSON 的模型：

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

import java.util.List;

public class YourResponseModel {
    @SerializedName("users")
    @Expose
    private List<String> users;

    public List<String> getUsers() {
        return users;
    }
}

这是 Login.java。我调用一个 API 来检查我是否成功登录：

import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import com.example.app.R;
import com.example.app.api.AndroidNCApi;
import com.example.app.api.ApiProvider;
import com.example.app.api.GsonConfig;
import com.example.app.database.model.Account;
import com.example.app.database.model.YourResponseModel;
import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
import com.owncloud.android.lib.common.OwnCloudClient;
import com.owncloud.android.lib.common.OwnCloudClientFactory;
import com.owncloud.android.lib.common.OwnCloudCredentials;
import com.owncloud.android.lib.common.OwnCloudCredentialsFactory;
import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.HttpException;
import retrofit2.Response;

import java.io.Reader;
import java.lang.reflect.Type;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class Login extends AppCompatActivity {

    private static final String TAG = "LoginActivity";
    private Button loginButton;
    private OwnCloudClient mClient;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);

        loginButton = findViewById(R.id.btnLogin);

        loginButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String username = "admin";
                String password = "admin";

                ExecutorService executor = Executors.newSingleThreadExecutor();
                executor.execute(new Runnable() {
                    @Override
                    public void run() {
                        performNetworkOperation(username, password);
                    }
                });
            }
        });
    }

    private void performNetworkOperation(String username, String password) {
        try {
            Uri serverUri = Uri.parse(getString(R.string.url_server));
            mClient = OwnCloudClientFactory.createOwnCloudClient(serverUri, Login.this, true);
            mClient.setCredentials(
                    OwnCloudCredentialsFactory.newBasicCredentials(username, password)
            );

            AndroidNCApi api = ApiProvider.getClient(Login.this).create(AndroidNCApi.class);

            Call<YourResponseModel> call = api.getNCUserIds();

            call.enqueue(new Callback<YourResponseModel>() {
                @Override
                public void onResponse(Call<YourResponseModel> call, Response<YourResponseModel> response) {
                    Log.e(TAG, "Response: " + response.body());
                    if (response.isSuccessful()) {
                        YourResponseModel responseData = response.body();
                        Log.e(TAG, "responseData: " + responseData.toString());
                        if (responseData != null) {
                            List<String> userIDs = responseData.getUsers();
                            Log.e(TAG, "User IDs: " + userIDs);

                            if (userIDs != null && !userIDs.isEmpty()) {
                                runOnUiThread(new Runnable() {
                                    @Override
                                    public void run() {
                                        Toast.makeText(Login.this, "Login successful", Toast.LENGTH_SHORT).show();
                                    }
                                });
                            } else {
                                runOnUiThread(new Runnable() {
                                    @Override
                                    public void run() {
                                        Toast.makeText(Login.this, "No user IDs found", Toast.LENGTH_SHORT).show();
                                    }
                                });
                            }
                        } else {
                            runOnUiThread(new Runnable() {
                                @Override
                                public void run() {
                                    Toast.makeText(Login.this, "Response is empty", Toast.LENGTH_SHORT).show();
                                }
                            });
                        }
                    } else {
                        runOnUiThread(new Runnable() {
                            @Override
                            public void run() {
                                Toast.makeText(Login.this, "Login failed", Toast.LENGTH_SHORT).show();
                            }
                        });
                    }
                }

                @Override
                public void onFailure(Call<YourResponseModel> call, Throwable t) {
                    Log.e(TAG, "Error: " + t.getMessage());
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            Toast.makeText(Login.this, "Network error", Toast.LENGTH_SHORT).show();
                        }
                    });
                }
            });
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}