RxJava结合Retrofit和Volley简单比较

通过使用Retrofit+RxJavaVolley获取知乎日报消息,比较两者的使用区别。

run.gif

文中 RR:代指Retrofit+Rxjava

主要两个方面使用

  1. 使用两者获取Json数据,使用Gson解析。
  2. 使用两者获取网络图片

1.第一步添加RR和Volley的gradle依赖

//google's volley
compile 'com.mcxiaoke.volley:library:1.0.19'
//RxAndroid
compile 'io.reactivex:rxandroid:1.2.1'
//RxJava
compile 'io.reactivex:rxjava:1.2.3'
//Retrofit
compile 'com.squareup.retrofit2:retrofit:2.1.0'
compile 'com.squareup.retrofit2:adapter-rxjava:2.1.0'
compile 'com.squareup.retrofit2:converter-gson:2.1.0'

2.分析知乎首页Api返回的Json格式

Api: http://news-at.zhihu.com/api/4/news/latest

Json.png

分析图片来自GitHub [izzyleung](https://github.com/izzyleung)/**[ZhihuDailyPurify](https://github.com/izzyleung/ZhihuDailyPurify)**

3.构建bean

在AndroidStudio里我是使用一个Json2Pojo插件,可以直接将Json对象转换为适合Gson的JavaBean

Json2Pojo

在AS的插件管理里可以直接安装 Json2Pojo

 /**
 * 知乎当日消息
 */
public class Stories {
    //供 Google Analytics 使用
    @SerializedName("ga_prefix")
    private String mGaPrefix;
    //url 与 share_url 中最后的数字(应为内容的 id)
    @SerializedName("id")
    private Long mId;
    //图像地址(官方 API 使用数组形式。目前暂未有使用多张图片的情形出现,曾见无 images 属性的情况,请在使用中注意 )
    @SerializedName("images")
    private List<String> mImages;
    //消息是否包含多张图片(仅出现在包含多图的新闻中)
    @SerializedName("multipic")
    private Boolean mMultipic;
    //消息标题
    @SerializedName("title")
    private String mTitle;
    //作用未知
    @SerializedName("type")
    private Long mType;

    public Stories(String mGaPrefix, Long mId, List<String> mImages, Boolean mMultipic, String mTitle, Long mType) {
        this.mGaPrefix = mGaPrefix;
        this.mId = mId;
        this.mImages = mImages;
        this.mMultipic = mMultipic;
        this.mTitle = mTitle;
        this.mType = mType;
    }

    public void setGaPrefix(String mGaPrefix) {
        this.mGaPrefix = mGaPrefix;
    }

    public void setId(Long mId) {
        this.mId = mId;
    }

    public void setImages(List<String> mImages) {
        this.mImages = mImages;
    }

    public void setMultipic(Boolean mMultipic) {
        this.mMultipic = mMultipic;
    }

    public void setTitle(String mTitle) {
        this.mTitle = mTitle;
    }

    public void setType(Long mType) {
        this.mType = mType;
    }

    public String getGaPrefix() {
        return mGaPrefix;
    }

    public Long getId() {
        return mId;
    }

    public List<String> getImages() {
        return mImages;
    }

    public Boolean getMultipic() {
        return mMultipic;
    }

    public String getTitle() {
        return mTitle;
    }

    public Long getType() {
        return mType;
    }

    @Override
    public String toString() {
        return "Stories{" +
                "mGaPrefix='" + mGaPrefix + '\'' +
                ", mId=" + mId +
                ", mImages=" + mImages +
                ", mMultipic=" + mMultipic +
                ", mTitle='" + mTitle + '\'' +
                ", mType=" + mType +
                '}';
    }
}

4.定义Retrofit和Volley的单例管理

获取Retrofit单例
public class RetrofitManager {
    static final String BASE_URL = "http://news-at.zhihu.com/api/4/news/";
    private Retrofit retrofit;
    private static RetrofitManager ourInstance = new RetrofitManager();

    public static RetrofitManager getInstance() {
        return ourInstance;
    }

    private RetrofitManager() {
    }

    /**
     * 获取retrofit单例
     *
     * @return Retrofit single
     */
    public Retrofit getRetrofit() {
        if (retrofit == null) {
            retrofit = new Retrofit.Builder()
                    .baseUrl(BASE_URL)
                    .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
                    .addConverterFactory(GsonConverterFactory.create())
                    .build();
        }
        return retrofit;
    }
}
获取Volley RequestQueue单例
public class VolleyManager {
    private RequestQueue requestQueue;
    private static VolleyManager ourInstance = new VolleyManager();

    public static VolleyManager getInstance() {
        return ourInstance;
    }

    private VolleyManager() {
    }

    /**
     * 获取 volley requestQueue 单例
     *
     * @param context activity
     * @return volley requestQueue
     */
    public RequestQueue getRequestQueue(Context context) {
        if (requestQueue == null) {
            requestQueue = Volley.newRequestQueue(context);
        }
        return requestQueue;
    }
}

5.定义Retrofit REST Api 接口

//获取Json数据
public interface GetNews {
    @GET("latest")
    Observable<Result> getNews();
}

//获取图片
public interface GetBitmap {
    @GET
    Observable<ResponseBody> getPicFromNet(@Url String url);
}

这里使用RxJava形式的接口定义,直接返回 被观察者对象

6.获取Json数据,并返回Result对象

通过RR获取
//get data by Retrofit & RxJava
private void getDataByRetrofit() {
    progressBar.setVisibility(View.VISIBLE);        
    storiesAdapter.setGetPicByRR(true);// tell adapter get pic by retrofit
    //RR:Retrofit+RxJava
    Subscriber<Result> subscriber = new Subscriber<Result>() {
        @Override
        public void onCompleted() {

        }

        @Override
        public void onError(Throwable e) {
            progressBar.setVisibility(View.INVISIBLE);
            Toast.makeText(context, e.getMessage(), Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onStart() {
            super.onStart();
            storiesList.clear();
        }

        //设置数据到RecyclerView
        @Override
        public void onNext(Result result) {
            storiesList.addAll(result.getStories());
            storiesAdapter.notifyDataSetChanged();
            progressBar.setVisibility(View.INVISIBLE);
        }
    };
    //主要逻辑
    GetNews getNews = RetrofitManager.getInstance().getRetrofit().create(GetNews.class);
    getNews.getNews()
            .subscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(subscriber);
}
通过Volley获取
/**
 * get data by volley
 */
private void getDataByVolley() {
    progressBar.setVisibility(View.VISIBLE);
    storiesAdapter.setGetPicByRR(false);// tell adapter get pic by volley
    //主要逻辑
    StringRequest stringRequest = new StringRequest(Request.Method.GET,
            RetrofitManager.BASE_URL + "latest",
            new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    //Json to Bean
                    Gson gson = new Gson();
                    Result result = gson.fromJson(response, Result.class);
                    storiesList.addAll(result.getStories());
                    //设置数据到RecyclerView
                    storiesAdapter.notifyDataSetChanged();
                    progressBar.setVisibility(View.INVISIBLE);
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    Toast.makeText(context, error.getMessage(), Toast.LENGTH_SHORT).show();
                }
            });
    VolleyManager.getInstance().getRequestQueue(this.getApplication()).add(stringRequest);
}

7.Adapter中获取图片

通过RR获取
//get pic by Retrofit and RxJava
        Action1<Bitmap> bitmapAction1 = new Action1<Bitmap>() {
            @Override
            public void call(Bitmap bitmap) {
                holder.ivImg.setImageBitmap(bitmap);
            }
        };
        String url = stories.getImages().get(0);
        GetBitmap getBitmap = RetrofitManager.getInstance().getRetrofit().create(GetBitmap.class);
        getBitmap.getPicFromNet(url)
                .map(new Func1<ResponseBody, Bitmap>() {
                    @Override
                    public Bitmap call(ResponseBody responseBody) {
                        //decode pic
                        return BitmapFactory.decodeStream(responseBody.byteStream());
                    }
                })
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(bitmapAction1);
通过Volley获取
//get pic by volley
        ImageLoader imageLoader = new ImageLoader(VolleyManager.getInstance()
                    .getRequestQueue(context.getApplicationContext())
                , new ImageLoader.ImageCache() {
            @Override
            public Bitmap getBitmap(String url) {
                return null;
            }

            @Override
            public void putBitmap(String url, Bitmap bitmap) {

            }
        });
        ImageLoader.ImageListener imageListener = ImageLoader.getImageListener(holder.ivImg, R.mipmap.ic_launcher, R.mipmap.ic_launcher);
        String url = stories.getImages().get(0);
        imageLoader.get(url, imageListener);

Project目录.png

8.总结

这里只是从简单的使用层面上对比了RR和Volley两者使用上的不同,之前获取网络数据的任务都是交给Volley来做。
有时获取了A数据之后,马上需要进行下一步包装分析A之后获取B数据。
如果是在Volley中就会出现嵌套的逻辑;在RxJava中使用Retrofit就可以使用它的map(或flatMap)进行A数据的包装分析,之后返回B数据的,就不会出现嵌套的逻辑。

以上只是小生简单的对比,用以自身理解RxJava,有什么不对的地方欢迎各位指出 ^_^

9.整体代码放在GitHub上,欢迎浏览

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