android - 有数据要处理的时候如何使用rxJava进行异步处理数据

问题描述

我需要实现下面这段代码，但是应该是耗时太长放在主界面会卡，所以希望异步处理

JsonReader jsonReader = new JsonReader();cityObject = jsonReader.jsonObject();try { cityArray = cityObject.getJSONArray('city_info'); for (int i=0;i<cityArray.length();i++) {Gson gson = new Gson();JSONObject city = (JSONObject) cityArray.get(i);cityDataList.add(gson.fromJson(city.toString(), CityData.class)); }} catch (JSONException e) { e.printStackTrace();}provinceList = getProvinceList();cityMap = getCityMap();

public class JsonReader { public JSONObject jsonObject(){InputStream inputStream = getClass().getClassLoader().getResourceAsStream('assets/cityList.json');InputStreamReader streamReader = new InputStreamReader(inputStream);BufferedReader reader = new BufferedReader(streamReader);String line;StringBuilder stringBuilder = new StringBuilder();try { while ((line = reader.readLine()) != null) {stringBuilder.append(line); } reader.close(); reader.close(); inputStream.close();} catch (IOException e) { e.printStackTrace();}try { JSONObject cityJson = new JSONObject(stringBuilder.toString()); return cityJson;} catch (JSONException e) { e.printStackTrace();}return null; }}

private List<String> getProvinceList() {List<String> list = new ArrayList<>();for (int i = 0; i < cityDataList.size(); i++) { CityData cityData = cityDataList.get(i); boolean isProvince = false; for (int j = 0; j < list.size(); j++) {if (list.get(j).equals(cityData.getProv())) { isProvince = true; break;} } if (isProvince) continue; else list.add(cityData.getProv());}return list; } private HashMap<String, List<String>> getCityMap() {HashMap<String, List<String>> map = new HashMap<>();for (int i = 0; i < provinceList.size(); i++) { String prov = provinceList.get(i); List<String> list = new ArrayList<>(); for (int j = 0; j < cityDataList.size(); j++) {if (cityDataList.get(j).getProv().equals(prov)) list.add(cityDataList.get(j).getCity()); } map.put(prov, list);}return map; }

这几个操作循环比较多，比较耗时，我想用rxjava处理，但是对observable的使用还是不太清楚，有人能介绍一下像我这样observable怎么写吗？我想要改进的是用observable通过flatmap等这些操作符来返回provinceList和cityMap,并且把线程转到后台，在前台接收到这两个数据就好了

问题解答

帮楼主写了下示例代码，像楼主这种需求，其实无须操作符进行变换的。

Observable.create(new Observable.OnSubscribe<Pair>() { @Override public void call(Subscriber<? super Pair> subscriber) {JsonReader jsonReader = new JsonReader();cityObject = jsonReader.jsonObject();try { cityArray = cityObject.getJSONArray('city_info'); for (int i=0;i<cityArray.length();i++) {Gson gson = new Gson();JSONObject city = (JSONObject) cityArray.get(i);cityDataList.add(gson.fromJson(city.toString(), CityData.class)); }} catch (JSONException e) { e.printStackTrace();}provinceList = getProvinceList();cityMap = getCityMap();Pair pair = new Pair(provinceList, cityMap); }}).subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread()).subscribe(new Subscriber<Pair>() { @Override public void onCompleted() { } @Override public void onError(Throwable e) { } @Override public void onNext(Pair pair) {//pair.first -> provinceList//pair.second -> cityMap }});回答2：

你需要的是cityDataList这个list吧？那么就可以使用Observable.create来新建一个Observable，把所有操作放在OnSubscribe对象中的call方法中，在最后数据准备完成后调用subscriber相应的onNext就行了。同时处理一下对应的onCompleted和onError