rxjava之数据分批加载

本文主要是介绍rxjava之数据分批加载，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

使用场景:

当从服务器请求的数据比较庞大时，这个时候，需要对数据进行分批处理，然后以当前的数据刷新界面

效果图:

原理分析图:

完整代码如下:

mDataInfo = new DataInfo();
List<Integer> objects = new ArrayList<>();
for (int i = 0; i < 4000; i++) {objects.add(i);
}
mDataInfo.l1 = objects;
objects = new ArrayList<>();
for (int i = 0; i < 8000; i++) {objects.add(i);
}
mDataInfo.l2 = objects;
objects = new ArrayList<>();
for (int i = 0; i < 12000; i++) {objects.add(i);
}Observable.concat(Observable.just(mDataInfo.l1), Observable.just(mDataInfo.l2), Observable.just(mDataInfo.l3)).subscribeOn(Schedulers.io()).concatMap(new Function<List<Integer>, Observable<NewPageInfo>>() {@Overridepublic Observable<NewPageInfo> apply(List<Integer> list1) throws Exception {LoggerUtils.loge("concatMap list1.size = " + list1.size());List<NewPageInfo> list = new ArrayList<>();int pageSize = list1.size() / 1000;int start = -1, end = 0;List<Integer> tmp = new ArrayList<>(list1);NewPageInfo newPageInfo = null;String tagStr = "";if (list1.size() == mDataInfo.l1.size()) {tagStr = "l1";} else if (list1.size() == mDataInfo.l2.size()) {tagStr = "l2";} else if (list1.size() == mDataInfo.l3.size()) {tagStr = "l3";}for (int i = 0; i < pageSize; i++) {// 0 : 0// 1 1000start = i * 1000;end = (i + 1) * 1000 - 1;LoggerUtils.loge("s : " + start + " , e : " + end);List<Integer> subList = tmp.subList(start, end);newPageInfo = new NewPageInfo();newPageInfo.tag = tagStr;newPageInfo.datas = subList;newPageInfo.page = i + "";list.add(newPageInfo);}ThreadUtils.doSleep(1500);return Observable.fromIterable(list);}}).observeOn(AndroidSchedulers.mainThread()).subscribe(new Consumer<NewPageInfo>() {@Overridepublic void accept(NewPageInfo newPageInfo) throws Exception {List<Integer> datas = newPageInfo.datas;int size = datas.size();String msg = "count : " + newPageInfo.page + " , dataSize : " + size + " " +", " + "scope : start : " + datas.get(0) + " , end : " + datas.get(size- 1);LoggerUtils.loge(msg);UiUtils.postDelayed(new Runnable() {@Overridepublic void run() {if ("l1".equalsIgnoreCase(newPageInfo.tag)) {line1.append(msg + "\r\n");} else if ("l2".equalsIgnoreCase(newPageInfo.tag)) {line2.append(msg + "\r\n");} else if ("l3".equalsIgnoreCase(newPageInfo.tag)) {line3.append(msg + "\r\n");}}}, 800);}});

场景二

以上的操作，对象为空了，直接就会抛出空指针的异常，流程没办法往下走了。

改进后的操作如下

示例代码

private void initData() {MPChartInfo mpChartInfo = new MPChartInfo();mDataInfo = new DataInfo();List<Integer> objects = new ArrayList<>();for (int i = 0; i < 1000; i++) {objects.add(i);}mDataInfo.name = "l1";mDataInfo.l1 = objects;mpChartInfo.V52 = mDataInfo;mDataInfo = new DataInfo();objects = new ArrayList<>();for (int i = 0; i < 2000; i++) {objects.add(i);}mDataInfo.l1 = objects;objects = new ArrayList<>();for (int i = 0; i < 3000; i++) {objects.add(i);}mDataInfo.l2 = objects;mDataInfo.name = "l2";mpChartInfo.V54 = mDataInfo;mDataInfo = new DataInfo();objects = new ArrayList<>();for (int i = 0; i < 3000; i++) {objects.add(i);}mDataInfo.l1 = objects;objects = new ArrayList<>();for (int i = 0; i < 4000; i++) {objects.add(i);}mDataInfo.l2 = objects;objects = new ArrayList<>();for (int i = 0; i < 5000; i++) {objects.add(i);}mDataInfo.name = "l3";mDataInfo.l3 = objects;mpChartInfo.V58 = mDataInfo;showUI(mpChartInfo);
} /*** 标识传递,空数据的处理*/
private void ll_02_03(MPChartInfo mpChartInfo) {mV52 = mpChartInfo.getV52();mV54 = mpChartInfo.getV54();mV54 = null;// 对象为空时就使用空的ObservableObservable empty = Observable.empty();mV58 = mpChartInfo.getV58();mV58 = null;Observable.concat(mV52 != null ? Observable.just(mV52) : empty, mV54 != null ? Observable.just(mV54) : empty, mV58 != null ? Observable.just(mV58) : empty).subscribeOn(Schedulers.io()).concatMap(new Function<DataInfo, Observable<Map<String, List<Integer>>>>() {@Overridepublic Observable<Map<String, List<Integer>>> apply(DataInfo dataInfo) throwsException {LoggerUtils.loge("concatMap apply = " + dataInfo.name);ThreadUtils.doSleep(300);List<Integer> l1 = dataInfo.l1;List<Integer> l2 = dataInfo.l2;List<Integer> l3 = dataInfo.l3;// 定义标识，标识一定要往下传递，要区分是刷新哪个控件使用 Map<String, List<Integer>> map = new LinkedHashMap<>();map.put(dataInfo.name, l1);// 对象为空或集合为空时，使用空的ObservableObservable<Map<String, List<Integer>>> source1 = l1 != null && l1.size()> 0 ?Observable.just(map) : empty;map = new LinkedHashMap<>();map.put(dataInfo.name, l2);Observable<Map<String, List<Integer>>> source2 = l2 != null && l2.size()> 0 ? Observable.just(map) : empty;map = new LinkedHashMap<>();map.put(dataInfo.name, l3);Observable<Map<String, List<Integer>>> source3 = l3 != null && l3.size()> 0 ?Observable.just(map) :empty;Observable<Map<String, List<Integer>>> concat = Observable.concat(source1, source2,source3);return concat;}}).subscribeOn(Schedulers.io()).concatMap(new Function<Map<String, List<Integer>>, Observable<NewPageInfo>>() {@Overridepublic Observable<NewPageInfo> apply(Map<String, List<Integer>> list1) throwsException {Iterator<Map.Entry<String, List<Integer>>> iterator = list1.entrySet().iterator();Map.Entry<String, List<Integer>> entry = iterator.next();List<Integer> entryValue = entry.getValue();String key = entry.getKey();LoggerUtils.loge("concatMap apply tag = " + key + " , list1.size " +"= " + entryValue.size());List<NewPageInfo> list = new ArrayList<>();int pageSize = entryValue.size() / 1000;int start = -1, end = 0;List<Integer> tmp = new ArrayList<>(entryValue);NewPageInfo newPageInfo = null;String tagStr = key;for (int i = 0; i < pageSize; i++) {// 0 : 0// 1 1000start = i * 1000;end = (i + 1) * 1000 - 1;
//                            LoggerUtils.loge("s : " + start + " , e : " + end);List<Integer> subList = tmp.subList(start, end);newPageInfo = new NewPageInfo();newPageInfo.tag = tagStr;newPageInfo.datas = subList;newPageInfo.page = i + "";list.add(newPageInfo);}ThreadUtils.doSleep(500);return Observable.fromIterable(list);}}).observeOn(AndroidSchedulers.mainThread()).subscribe(new Consumer<NewPageInfo>() {@Overridepublic void accept(NewPageInfo newPageInfo) throws Exception {List<Integer> datas = newPageInfo.datas;int size = datas.size();String msg = "count : " + newPageInfo.page + " , dataSize : " + size + " " +", " + "scope : start : " + datas.get(0) + " , end : " + datas.get(size- 1);LoggerUtils.loge("consumer name = " + newPageInfo.tag + " , dataSize : "+ size);UiUtils.postDelayed(new Runnable() {@Overridepublic void run() {// 根据标签刷新控件if ("l1".equalsIgnoreCase(newPageInfo.tag)) {line1.append(msg + "\r\n");} else if ("l2".equalsIgnoreCase(newPageInfo.tag)) {line2.append(msg + "\r\n");} else if ("l3".equalsIgnoreCase(newPageInfo.tag)) {line3.append(msg + "\r\n");}}}, 400);}});
}

简书文章地址

这篇关于rxjava之数据分批加载的文章就介绍到这儿，希望我们推荐的文章对编程师们有所帮助！

---