以项目中的登陆模块为例演示MVP+retrofit+rxjava的使用

依赖

    //网络库
    implementation 'com.squareup.retrofit2:retrofit:2.4.0'
    implementation 'com.squareup.okhttp3:okhttp:3.11.0'
    //json解析
    implementation 'com.squareup.retrofit2:converter-gson:2.4.0'
    implementation 'com.google.code.gson:gson:2.8.5'
    //rx相关
    implementation 'io.reactivex.rxjava2:rxjava:2.2.0'
    implementation 'io.reactivex.rxjava2:rxandroid:2.0.2'
    implementation 'com.squareup.retrofit2:adapter-rxjava2:2.4.0'

封装网络请求

Api:
public interface ApiService {
   @POST(ApiNameConstant.LOGIN)
    Observable<UserInfo> doLogin(@Body RequestBody body);
}
Method:
public class HttpMethods {

    private static final int DEFAULT_TIMEOUT = 20;//默认超时时间
    private Retrofit mRetrofit;
    private ApiService mService;
    private static Gson gson;
    private String baseUrl = ApiNameConstant.BASE_URL;

    public void setBaseUrl(String baseUrl) {
        this.baseUrl = baseUrl;
    }

    private HttpMethods() {
        init(baseUrl);
    }

    private void init(String url) {
        //创建OKHttpClient
        OkHttpClient.Builder client = new OkHttpClient.Builder();
        client.connectTimeout(DEFAULT_TIMEOUT, TimeUnit.SECONDS);
        mRetrofit = new Retrofit.Builder()
                .client(client.build())
                .addConverterFactory(GsonConverterFactory.create(buildGson()))
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .baseUrl(url)
                .build();
        mService = mRetrofit.create(ApiService.class);
    }

    private static Gson buildGson() {
        if (gson == null) {
            gson = new GsonBuilder()
                    .registerTypeAdapter(Integer.class, new IntegerDefault0Adapter())
                    .registerTypeAdapter(int.class, new IntegerDefault0Adapter())
                    .registerTypeAdapter(Double.class, new DoubleDefault0Adapter())
                    .registerTypeAdapter(double.class, new DoubleDefault0Adapter())
                    .registerTypeAdapter(Long.class, new LongDefault0Adapter())
                    .registerTypeAdapter(long.class, new LongDefault0Adapter())
                    .registerTypeAdapter(String.class, new StringDefault0Adapter())
                    .create();
        }
        return gson;
    }

    private static final HttpMethods INSTANCE = new HttpMethods();
    
    public static HttpMethods getInstance() {
        return INSTANCE;
    }

    /**
     * 登录
     *
     * @param subscriber
     * @param body
     */
    public void login(ProgressSubscriber<UserInfo> subscriber, RequestBody body) {
        mService.doLogin(body)
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(subscriber);
    }
}

ProgressSubscriber类来自于
https://github.com/zhou-you/RxEasyHttp实现带有进度的订阅
Model：

public interface ILoginModel {

    void login(Context context, String userName, String password, OnLoginListener listener);

    interface OnLoginListener {
        void onLoginFail(String errorMsg);

        void onLoginSuccess(String token, String userId);
    }

}

public class LoginModel implements ILoginModel {

    @Override
    public void login(final Context context,String userName, String password, final OnLoginListener listener) {
        RequestBody body = getBody(userName, password);
        IProgressDialog dialog = UIUtils.getProgressDialog(context, "登录中...");
        HttpMethods.getInstance().login(new ProgressSubscriber<UserInfo>(dialog,
                true, true) {
            @Override
            public void onError(ApiException e) {
                super.onError(e);
                listener.onLoginFail(e.getMessage());
            }

            @Override
            public void onNext(UserInfo loginResponseInfo) {
                super.onNext(loginResponseInfo);
                // TODO: 根据返回json格式，做非空判断和成功失败的判断
                listener.onLoginSuccess(data.getToken(), data.getUserId());
                 listener.onLoginFail(e.getMessage());
            }
        }, body);
    }

    @NonNull
    private RequestBody getBody(String userName, String password) {
        LoginParams params = new LoginParams();
        params.setLoginName(userName);
        params.setLoginPwd(password);
        params.setSourceCode(AppConstant.SOURCE_TIME_SHARE);
        String json = JsonUtil.toJson(params,1);
        return RequestBody.create(MediaType.parse("application/json;charset=UTF-8"), json);
    }

}

Presenter：调用Model中的方法，回调交给View来处理

public interface ILoginPresenter {
    void login(String userName, String password);
}

public class LoginPresenter implements ILoginPresenter {

    private Context context;
    private ILoginView view;
    private ILoginModel model;

    public LoginPresenter(Context context, ILoginView view) {
        this.context = context;
        this.view = view;
        model=new LoginModel();
    }

    @Override
    public void login(String userName, String password) {
        model.login(context, userName, password, new ILoginModel.OnLoginListener() {
            @Override
            public void onLoginFail(String errorMsg) {
                view.onLoginFail(errorMsg);
            }

            @Override
            public void onLoginSuccess(String token, String userId) {
                view.onLoginSuccess(token,userId);
            }
        });
    }
}

View:

public interface ILoginView {

    void onLoginFail(String errorMsg);

    void onLoginSuccess(String token, String userId);

}

使用：

public class LoginActivity extends BaseActivity implements ILoginView {
    private ILoginPresenter presenter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        setContentView(R.layout.activity_login);
        ButterKnife.bind(this);
        presenter = new LoginPresenter(this, this);
    }
    
    @OnClick({R.id.btn_login})
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.btn_login:
                login();
                break;
        }
    }

    private void login() {
        String phone = etPhone.getText().toString().trim();
        String pwd = etPwd.getText().toString().trim();
        ...
        检查手机号格式和密码格式
        MD5加密密码
        ...
        presenter.login(phone, pwd);       
    }

    @Override
    public void onLoginFail(String errorMsg) {
        ToastUtil.showShortToast(errorMsg);
    }

    @Override
    public void onLoginSuccess(String token, String userId) {
        // TODO: 保存数据
        finish();
    }
}