December 2019
Beginner to intermediate
330 pages
10h 7m
Chinese
Content preview from RxJava反应式编程
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62
｜
第
3
章
3.2.1
使用
merge()
将多个
Observable
合并为一个
还记得
3.1.2
节中的 Observable<LicensePlate> recognize(CarPhoto photo) 方法吗？这个
方法会异步地根据 CarPhoto 识别 LicensePlate。我们曾经简单地提过这样的流可能会同时
使用多个算法，有的可能会更快，有的可能会更精确。但是，我们并不想将这些细节暴露
给外部世界，只是想有一个包含渐进式优化结果的流，这个结果来源于各个算法，从最快
的到最精确的。
假设现在有三个支持
RxJava
的算法，每个算法都使用 Observable 进行了很好的封装。当
然，每个算法可能会生成零个到无穷个结果。
Observable<LicensePlate> fastAlgo(CarPhoto photo) {
//速度快但质量差
}
Observable<LicensePlate> preciseAlgo(CarPhoto photo) {
//精确但代价高昂
}
Observable<LicensePlate> experimentalAlgo(CarPhoto photo) {
//不可预测，但是可运行
}
我们想要达到的效果是同时运行这三个算法（参见
4.9.2
节，了解
RxJava
处理并发的更多
细节）并尽快接收结果。我们并不关心是哪个算法发布了事件，只想要捕获所有的事件并
将它们聚集到一个流中。这就是 merge() 操作符能实现的功能，如下所示。
Observable<LicensePlate> ...
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