Android背锅侠

RxJava + Retrofit2 + OkHttp3 封装及踩坑

Veröffentlicht am

网上对这三个开源库的组合框架代码已经一搜一大把了，但是都很零碎，需要搜索很多东拼西凑才能写一套完整的复合自己需求的框架。这篇文章就是我自己在封装过程遇到的各种问题的记录和总结，免得很多人重复踩坑。。

一、封装后的效果

private void requestTopMovies(int page) {
    showWaitingDialog();
    Subscriber subscriber = new RxCallback<List<Movie>>() {
        @Override
        public void onSuccess(List<Movie> movieList) {
            if (adapter != null) {
                adapter.updateData(movieList);
            }
        }
        @Override
        public void onFinished() {
            dismissWaitingDialog();
        }
    };
    
    RxRetrofitClient.getInstance().requestTop250Movies(subscriber, page, 10);
}

二、封装过程

1. 全局Client管理类封装 RxRetrofitClient（单例）

在这里初始化各种网络设置

/// RxRetrofitClient.java
private void initClient() {
    // 创建OkHttpClient
    OkHttpClient.Builder builder = new OkHttpClient.Builder()
            // 超时设置
            .connectTimeout(DEFAULT_CONNECT_TIMEOUT, TimeUnit.SECONDS)
            .readTimeout(DEFAULT_READ_TIMEOUT, TimeUnit.SECONDS)
            .writeTimeout(DEFAULT_WRITE_TIMEOUT, TimeUnit.SECONDS)
            // 错误重连
            .retryOnConnectionFailure(true)
            // 支持HTTPS
            .connectionSpecs(Arrays.asList(ConnectionSpec.CLEARTEXT, ConnectionSpec.MODERN_TLS)) //明文Http与比较新的Https
            // cookie管理
            .cookieJar(new PersistentCookieJar(new SetCookieCache(), new SharedPrefsCookiePersistor(App.getInstance())));
    // 添加各种插入器
    addInterceptor(builder);
    // 创建Retrofit实例
    Retrofit doubanRetrofit = new Retrofit.Builder()
            .client(builder.build())
            .addConverterFactory(GsonConverterFactory.create())
            // .addConverterFactory(FastJsonConvertFactory.create())
            .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
            .baseUrl(BASE_URL_DOUBAN)
            .build();
    // 创建API接口类
    doubanApi = doubanRetrofit.create(IDoubanApi.class);
}
private void addInterceptor(OkHttpClient.Builder builder) {
    // 添加Header
    builder.addInterceptor(new HttpHeaderInterceptor());
    // 添加缓存控制策略
    File cacheDir = App.getInstance().getExternalCacheDir();
    Cache cache = new Cache(cacheDir, DEFAULT_CACHE_SIZE);
    builder.cache(cache).addInterceptor(new HttpCacheInterceptor());
    // 添加http log
    HttpLoggingInterceptor logger = new HttpLoggingInterceptor();
    logger.setLevel(HttpLoggingInterceptor.Level.BODY);
    builder.addInterceptor(logger);
    // 添加调试工具
    builder.networkInterceptors().add(new StethoInterceptor());
}

2. Get和Post请求封装
/**
 * 豆瓣 Retrofit API
 *
 * Created by XiaoFeng on 16/12/20.
 */
public interface IDoubanApi {
    @GET("top250")
    Observable<DoubanResult<List<Movie>>> getTopMovies(@Query("start") int start, @Query("count") int count);
    /**
     * Json格式的Post请求（application/json）
     */
    @POST("account/update_user_info")
    Observable<RESTResult<String>> updateUserInfo(@Body RequestBody body);
    /**
     * Form格式的Post请求（application/x-www-form-urlencoded）
     */
    @FormUrlEncoded
    @POST("account/update_user_info")
    Observable<RESTResult<String>> updateUserInfo(@FieldMap Map<String, String> params);
}
/// RxRetrofitClient.java
/**
 * 获取豆瓣电影Top250的列表数据
 *
 * @param subscriber 由调用者传过来的观察者对象
 * @param page       页码
 * @param count      每页个数
 */
public void requestTop250Movies(Subscriber<List<Movie>> subscriber, int page, int count) {
    doubanApi.getTopMovies(page * count, count)
            .map(RxUtil.<List<Movie>>handleDoubanResult())
            .compose(RxUtil.<List<Movie>>normalSchedulers())
            .subscribe(subscriber);
}
/**
 * 修改用户信息
 * Json格式
 *
 * @param subscriber
 * @param params
 */
public void updateUserInfo(Subscriber<String> subscriber, Map<String, Object> params) {
    xzApi.updateUserInfo(toRequestBody(params))
            .map(RxUtil.<String>handleRESTFulResult())
            .compose(RxUtil.<String>normalSchedulers())
            .subscribe(subscriber);
}
/**
 * 修改用户信息
 * Form格式
 *
 * @param subscriber
 * @param params
 */
public void updateUserInfo(Subscriber<String> subscriber, Map<String, Object> params) {
    xzApi.updateUserInfo(params)
            .map(RxUtil.<String>handleRESTFulResult())
            .compose(RxUtil.<String>normalSchedulers())
            .subscribe(subscriber);
}

这里有几个 坑

  1. 写Form格式的Post请求时，需要添加 @FormUrlEncoded 注解，否则编译器会报错
  2. 写Json格式的Post请求时，不使用@FieldMap注解，而是使用 @Body 注解，并声明 RequestBody 类型变量
3. RequestBody封装
private RequestBody toRequestBody(Map params) {
    return RequestBody.create(JSON, toJsonStr(params));
}
private String toJsonStr(Map params) {
    return new JSONObject(params).toString();
}
4. 对请求结果统一封装 RESTResult
/**
 * RESTFul 返回值封装类
 *
 * Created by XiaoFeng on 16/12/21.
 */
public class RESTResult<T> {
    public static final int FAILURE = 0;
    public static final int SUCCESS = 1;
    @SerializedName("res")
    private int res;
    @SerializedName("msg")
    private String msg;
    @SerializedName("data")
    T data;
    public int getRes() {
        return res;
    }
    public void setRes(int res) {
        this.res = res;
    }
    public String getMsg() {
        return msg;
    }
    public void setMsg(String msg) {
        this.msg = msg;
    }
    public T getData() {
        return data;
    }
    public void setData(T data) {
        this.data = data;
    }
}
5. 对请求结果进行转换和预处理（map）
/// RxUtil.java
/**
 * 对RESTful返回结果做预处理，对逻辑错误抛出异常
 *
 * @param <T>
 * @return
 */
public static <T> Func1<RESTResult<T>, T> handleRESTFulResult() {
    return new Func1<RESTResult<T>, T>() {
        @Override
        public T call(RESTResult<T> restResult) {
            if (restResult.getRes() != RESTResult.SUCCESS) {
                throw new ApiException(restResult.getRes(), restResult.getMsg());
            }
            return restResult.getData();
        }
    };
}
6. rxjava线程切换封装（compose）
/// RxUtil.java
/**
 * 普通线程切换: IO -> Main
 *
 * @param <T>
 * @return
 */
public static <T> Observable.Transformer<T, T> normalSchedulers() {
    return new Observable.Transformer<T, T>() {
        @Override
        public Observable<T> call(Observable<T> source) {
            return source.subscribeOn(Schedulers.io())
                    .observeOn(AndroidSchedulers.mainThread());
        }
    };
}

这里有一个 坑 ：
我把handleRESTFulResult和normalSchedulers封装到了单独的帮助类RxUtil中，这样在使用map或者compose做转换时，需要显式写明返回类型，不然编译器会报错，这点在很多网上查找的资料中都没有提及

.map(RxUtil.handleRESTFulResult())
.compose(RxUtil.normalSchedulers())

7. 对服务器返回的逻辑错误进行统一拦截和封装，抛出异常
/**
 * 对服务器返回的逻辑错误值进行封装
 *
 * Created by XiaoFeng on 16/12/21.
 */
public class ApiException extends RuntimeException {
    private static final int USER_NOT_EXIST = 100;
    private static final int WRONG_PASSWORD = 101;
    private int errorCode;
    public ApiException(String detailMessage) {
        super(detailMessage);
    }
    public ApiException(int resultCode) {
        this(resultCode, toApiExceptionMessage(resultCode));
    }
    public ApiException(int resultCode, String detailMessage) {
        super(detailMessage);
        this.errorCode = resultCode;
    }
    public int getErrorCode() {
        return errorCode;
    }
    /**
     * 映射服务器返回的自定义错误码，
     * （此时的http状态码在[200, 300) 之间）
     *
     * @param resultCode
     * @return
     */
    private static String toApiExceptionMessage(int resultCode) {
        String message;
        switch (resultCode) {
            case USER_NOT_EXIST:
                message = "该用户不存在";
                break;
            case WRONG_PASSWORD:
                message = "密码错误";
                break;
            default:
                message = "未知错误";
        }
        return message;
    }
}
8. 对Subscriber的封装，同时对onError异常再次封装
/**
 * 暴露给最上层的网络请求回调处理类
 *
 * Created by XiaoFeng on 16/12/28.
 */
public abstract class RxCallback<T> extends Subscriber<T> {
    /**
     * 成功返回结果时被调用
     *
     * @param t
     */
    public abstract void onSuccess(T t);
    /**
     * 成功或失败到最后都会调用
     */
    public abstract void onFinished();
    @Override
    public void onCompleted() {
        onFinished();
    }
    @Override
    public void onError(Throwable e) {
        String errorMsg;
        if (e instanceof IOException) {
            /** 没有网络 */
            errorMsg = "Please check your network status";
        } else if (e instanceof HttpException) {
            /** 网络异常，http 请求失败，即 http 状态码不在 [200, 300) 之间, such as: "server internal error". */
            errorMsg = ((HttpException) e).response().message();
        } else if (e instanceof ApiException) {
            /** 网络正常，http 请求成功，服务器返回逻辑错误 */
            errorMsg = e.getMessage();
        } else {
            /** 其他未知错误 */
            errorMsg = !TextUtils.isEmpty(e.getMessage()) ? e.getMessage() : "unknown error";
        }
        Toast.makeText(App.getInstance(), errorMsg, Toast.LENGTH_SHORT).show();
        onFinished();
    }
    @Override
    public void onNext(T t) {
        onSuccess(t);
    }
}

参考：
https://gank.io/post/56e80c2c677659311bed9841
http://tech.glowing.com/cn/glow-android-performance-optimization/
http://www.jianshu.com/p/f3f0eccbcd6f
http://wuxiaolong.me/2016/06/18/retrofits/
http://stackoverflow.com/questions/35243785/rxjava-static-generic-utility-method-with-transformer