zip操作符的error处理

熟悉rxjava的同学肯定对操作符不会陌生，比如我们使用map操作符处理数据，使用zip操作符合并多个请求，这里演示下zip操作符的对error情况的处理。

比如说我们同时请求了两个接口，在两个接口都响应的情况下才会展示数据，这里我们使用zip操作符来实现。

zip操作符合并请求

我们先模拟两个请求的响应：responseOneObservable和responseTwoObservable，这里responseTwoObservable我们模拟了错误的场景——onError.

Observable<ZipOneBean> responseOneObservable = Observable.create(new ObservableOnSubscribe<ZipOneBean>() {
    @Override
    public void subscribe(ObservableEmitter<ZipOneBean> emitter) {
        ZipOneBean zipOneBean = new ZipOneBean();
        zipOneBean.setName("zipOneBean");
        emitter.onNext(zipOneBean);
        emitter.onComplete();
    }
})
        .subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread());

Observable<ZipTwoBean> responseTwoObservable = Observable.create(new ObservableOnSubscribe<ZipTwoBean>() {
    @Override
    public void subscribe(ObservableEmitter<ZipTwoBean> emitter) {
        ZipTwoBean zipTwoBean = new ZipTwoBean();
        zipTwoBean.setName("zipTwoBean");
        emitter.onError(new RuntimeException("阿西吧"));
    }
})
        .subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread());

接着使用zip操作符进行合并：

Observable.zip(responseOneObservable, responseTwoObservable, new BiFunction<ZipOneBean, ZipTwoBean, ArrayList<ZipBaseData>>() {
    @Override
    public ArrayList<ZipBaseData> apply(ZipOneBean zipOneBean, ZipTwoBean zipTwoBean) {
        ArrayList<ZipBaseData> testDataList = new ArrayList();
        // Add test data from response responseOne & responseTwo
        testDataList.add(zipOneBean);
        testDataList.add(zipTwoBean);
        return testDataList;
    }
}).subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread())
        .subscribe(new Observer<ArrayList<ZipBaseData>>() {
            @Override
            public void onSubscribe(Disposable d) {
                Log.e(TAG, "onSubscribe");
            }

            @Override
            public void onNext(ArrayList<ZipBaseData> zipBaseData) {
                Log.e(TAG, "onNext zipBaseData:" + zipBaseData);
            }

            @Override
            public void onError(Throwable e) {
                Log.e(TAG, "onError e:" + e.getMessage());
            }

            @Override
            public void onComplete() {
                Log.e(TAG, "onComplete");
            }
        });

运行代码，输出结果如下：最终走的是onError方法，

E/ZipErrorHandle: onSubscribe
E/ZipErrorHandle: onError e:阿西吧

onErrorReturn

这种做法肯定不能满足需求，如果两个接口中的一个挂了，导致另外一个正常接口的数据也不展示，这个明显不合逻辑。所以我们需要在请求响应错误的时候做下处理，返回默认数据或者特定的数据，标识这个请求失败，不影响别的接口的数据展示。代码如下：

Observable<ZipOneBean> responseOneObservable = Observable.create(new ObservableOnSubscribe<ZipOneBean>() {
    @Override
    public void subscribe(ObservableEmitter<ZipOneBean> emitter) {
        ZipOneBean zipOneBean = new ZipOneBean();
        zipOneBean.setName("zipOneBean");
        emitter.onNext(zipOneBean);
        emitter.onComplete();
    }
}).onErrorReturn(new Function<Throwable, ZipOneBean>() {
    @Override
    public ZipOneBean apply(Throwable throwable) {
        ZipOneBean zipOneBean = new ZipOneBean();
        zipOneBean.setName("大哥我错了，我是zipOneBean");
        return zipOneBean;
    }
})
        .subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread());

Observable<ZipTwoBean> responseTwoObservable = Observable.create(new ObservableOnSubscribe<ZipTwoBean>() {
    @Override
    public void subscribe(ObservableEmitter<ZipTwoBean> emitter) {
        ZipTwoBean zipTwoBean = new ZipTwoBean();
        zipTwoBean.setName("zipTwoBean");
        emitter.onError(new RuntimeException("阿西吧"));
    }
}).onErrorReturn(new Function<Throwable, ZipTwoBean>() {
    @Override
    public ZipTwoBean apply(Throwable throwable) {
        ZipTwoBean zipTwoBean = new ZipTwoBean();
        zipTwoBean.setName("大哥我错了，我是zipTwoBean");
        return zipTwoBean;
    }
})
        .subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread());

接下来我们再运行代码，输出如下：

E/ZipErrorHandle: onSubscribe
E/ZipErrorHandle: onNext zipBaseData:[ZipBaseData{name='zipOneBean'}, ZipBaseData{name='大哥我错了，我是zipTwoBean'}]
E/ZipErrorHandle: onComplete

可以看出即使一个请求出错，也是走了成功的回调的。

参考

https://stackoverflow.com/questions/41342844/rxjava-how-to-handle-error-with-zip-operator