Android 使用 Retrofit 发送网络请求

简介

在Android应用中，如果不是单机的话，应该都有请求后端接口API的情况，本篇文章就介绍下Retrofit在Android中如何进行使用的

相关代码

我们以一个简单的登录接口为例

完整代码GitHub上有：github.com/lw124392545…

仅做代码参考，目前数据监控上传是有了，但界面这些还很粗糙，没有完善

相关的依赖引入

首先我们在工程中引入相关的依赖：

    implementation 'com.squareup.okhttp3:okhttp:4.5.0'

    implementation 'com.squareup.retrofit2:retrofit:2.9.0'

    implementation 'com.squareup.retrofit2:converter-gson:2.9.0'

相关的手机权限开启

需要在文件中开启网络权限：

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.example.selfgrowth">


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


    <application

    ......

    </application>


</manifest>

配置Retrofit Client

Client的相关配置：单例，配置基于OKHTTP，Gson序列化;OKHTTP中添加了请求拦截器

@Data

public class RetrofitClient {


    private static final RetrofitClient instance = new RetrofitClient();


    private final Retrofit retrofit = new Retrofit.Builder()

            .baseUrl(HttpConfig.ADDRESS) //基础url,其他部分在GetRequestInterface里

            .client(httpClient())

            .addConverterFactory(GsonConverterFactory.create()) //Gson数据转换器

            .build();


    public static RetrofitClient getInstance() {

        return instance;

    }


    private OkHttpClient httpClient() {

        return new OkHttpClient.Builder()

                .addInterceptor(new AccessTokenInterceptor())

                .connectTimeout(20, TimeUnit.SECONDS)

                .build();

    }

}

配置通用的请求拦截器

比如在请求中，带上Authorization等

public class AccessTokenInterceptor implements Interceptor {


    @NonNull

    @Override

    public Response intercept(@NonNull Chain chain) throws IOException {

        if (UserCache.getInstance().getToken() == null) {

            return chain.proceed(chain.request());

        }


        Request original = chain.request();

        Request.Builder requestBuilder = original.newBuilder()

                .addHeader("Authorization", UserCache.getInstance().getToken());

        Request request = requestBuilder.build();

        return chain.proceed(request);

    }

}

Retrofit接口定义

登录请求的接口定义：

public interface UserApi {


    /**

     * 用户登录

     **/

    @POST("auth/user/login")

    Call<ApiResponse> login(@Body LoginUser user);

}

Retrofit Request具体请求编写

我们首先定义一个抽象类，在其中持有我们的RetrofitClient全局类，在其中发起请求，由于Android UI的形式，请求是异步的

public abstract class Request {


    final Retrofit retrofit;


    public Request() {

        this.retrofit = RetrofitClient.getInstance().getRetrofit();

    }


    /**

     * 发送网络请求(异步)

     * @param call call

     */

    void sendRequest(Call<ApiResponse> call, Consumer<? super Object> success, Consumer<? super Object> failed) {

        call.enqueue(new Callback<ApiResponse>() {

            @Override

            public void onResponse(Call<ApiResponse> call, Response<ApiResponse> response) {

                if (response.code() != 200) {

                    Log.w("Http Response", "请求响应错误");

                    failed.accept(response.raw().message());

                    return;

                }

                if (response.body() == null || response.body().getData() == null) {

                    success.accept(null);

                    return;

                }

                Object res = response.body().getData();

                if (String.valueOf(res).isEmpty()) {

                    success.accept(null);

                    return;

                }

                success.accept(res);

            }


            @Override

            public void onFailure(Call<ApiResponse> call, Throwable t) {

                System.out.println("GetOutWarehouseList->onFailure(MainActivity.java): "+t.toString() );

            }

        });

    }

}

如上所示，请求成功就执行success相关的逻辑，失败则执行failed相关的逻辑

登录请求的具体逻辑如下：构造Retrofit Interface，发起请求

public class UserRequest extends Request {


    public void login(LoginUser user, Consumer<? super Object> success, Consumer<? super Object> failed) {

        UserApi request = retrofit.create(UserApi.class);

        Call<ApiResponse> call = request.login(user);

        sendRequest(call, success, failed);

    }

}

Android UI中进行调动

使用示例如下，点击一个登录按钮后触发

public class LoginFragment extends Fragment {


    private final UserRequest userRequest = new UserRequest();


    @Nullable

    @Override

    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

        View rootView = inflater.inflate(R.layout.fragment_login, container, false);

        Button loginButton = rootView.findViewById(R.id.login_button);

        loginButton.setOnClickListener(view -> {

            EditText email = rootView.findViewById(R.id.login_email_edit);

            EditText password = rootView.findViewById(R.id.login_password_edit);


            final LoginUser user = LoginUser.builder()

                    .email(email.getText().toString())

                    .password(password.getText().toString())

                    .build();


            // 获取相关的用户名和密码后，调用登录接口

            userRequest.login(user, (token) -> {

                UserCache.getInstance().initUser(email.getText().toString(), token.toString());

                final SharedPreferences preferences = requireContext().getSharedPreferences("userInfo", Context.MODE_PRIVATE);

                final SharedPreferences.Editor edit = preferences.edit();

                edit.putString("username", email.getText().toString());

                edit.putString("password", password.getText().toString());

                edit.apply();

                Snackbar.make(view, "登录成功:" + token.toString(), Snackbar.LENGTH_LONG)

                        .setAction("Action", null).show();

            }, failedMessage -> {

                Snackbar.make(view, "登录失败:" + failedMessage, Snackbar.LENGTH_LONG)

                        .setAction("Action", null).show();

            });

        });

        return rootView;

    }


    @Override

    public void onActivityCreated(@Nullable Bundle savedInstanceState) {

        super.onActivityCreated(savedInstanceState);

        final SharedPreferences preferences = getActivity().getSharedPreferences("userInfo", Activity.MODE_PRIVATE);

        final String userName = preferences.getString("username", "");

        final String password = preferences.getString("password", "");

        final EditText emailEdit = getView().findViewById(R.id.login_email_edit);

        final EditText passwordEdit = getView().findViewById(R.id.login_password_edit);

        emailEdit.setText(userName);

        passwordEdit.setText(password);

    }

}

总结

本篇文章中介绍了如Android学习中如何使用Retrofit发起网络请求

但由于吃初学，虽然感觉能用，但有点繁琐，不知道在实际的Android开发中，网络请求的最近实践是怎么样的，如果有的话，大佬可以在评论区告知下，感谢