看完不懂Rxjava我跪搓板（3）

2018-05-19 本文已影响17人付凯强

0. 为了月薪1.8万

奋斗方向和目标.png

1. 序言

上一篇博客讲述的是过滤操作符，如需了解，请点击跳转阅读：https://www.jianshu.com/p/154da44670de

2. 组合操作符

startWith：在源Observable数据前插上一些数据：

  Observable.just("Hello", "World", "Hello").startWith("Beijing", "上海", "广州")
                .subscribe(new Action1<String>() {
                    @Override
                    public void call(String s) {
                        Log.i(TAG, "Action1: String:" + s);
                    }
                });

05-18 20:46:32.343 1658-1658/com.best.testrxjava I/MainActivity: Action1: String:Beijing
05-18 20:46:32.343 1658-1658/com.best.testrxjava I/MainActivity: Action1: String:上海
05-18 20:46:32.343 1658-1658/com.best.testrxjava I/MainActivity: Action1: String:广州
05-18 20:46:32.343 1658-1658/com.best.testrxjava I/MainActivity: Action1: String:Hello
05-18 20:46:32.343 1658-1658/com.best.testrxjava I/MainActivity: Action1: String:World
05-18 20:46:32.344 1658-1658/com.best.testrxjava I/MainActivity: Action1: String:Hello

merge:

将多个Observable合并为一个Observable。

Observable<String> obs1 = Observable.just("A", "B", "C");
        Observable<String> obs2 = Observable.just("D", "E", "F");
        Observable<String> obs3 = Observable.just("G", "H", "I");
        Observable<String> obs4 = Observable.just("G", "K", "L");
        Observable.merge(obs1,obs2,obs3,obs4).subscribe(new Action1<String>() {
            @Override
            public void call(String s) {
                Log.i(TAG, "Action1: String:" + s);
            }
        });

05-18 21:05:20.709 2032-2032/com.best.testrxjava I/MainActivity: Action1: String:A
05-18 21:05:20.709 2032-2032/com.best.testrxjava I/MainActivity: Action1: String:B
05-18 21:05:20.709 2032-2032/com.best.testrxjava I/MainActivity: Action1: String:C
05-18 21:05:20.709 2032-2032/com.best.testrxjava I/MainActivity: Action1: String:D
05-18 21:05:20.709 2032-2032/com.best.testrxjava I/MainActivity: Action1: String:E
05-18 21:05:20.710 2032-2032/com.best.testrxjava I/MainActivity: Action1: String:F
05-18 21:05:20.710 2032-2032/com.best.testrxjava I/MainActivity: Action1: String:G
05-18 21:05:20.710 2032-2032/com.best.testrxjava I/MainActivity: Action1: String:H
05-18 21:05:20.710 2032-2032/com.best.testrxjava I/MainActivity: Action1: String:I
05-18 21:05:20.710 2032-2032/com.best.testrxjava I/MainActivity: Action1: String:G
05-18 21:05:20.710 2032-2032/com.best.testrxjava I/MainActivity: Action1: String:K
05-18 21:05:20.710 2032-2032/com.best.testrxjava I/MainActivity: Action1: String:L

merge合并可能发生错乱（Observable订阅的线程不同时）

Observable<String> obs1 = Observable.just("A", "B", "C").subscribeOn(Schedulers.io());
        Observable<String> obs2 = Observable.just("D", "E", "F").subscribeOn(Schedulers.io());
        Observable<String> obs3 = Observable.just("G", "H", "I");
        Observable.merge(obs1,obs2,obs3).subscribe(new Action1<String>() {
            @Override
            public void call(String s) {
                Log.i(TAG, "Action1: String:" + s);
            }
        });

05-18 21:21:44.646 2489-2489/? I/MainActivity: Action1: String:G
05-18 21:21:44.646 2489-2489/? I/MainActivity: Action1: String:H
05-18 21:21:44.646 2489-2489/? I/MainActivity: Action1: String:I
05-18 21:21:44.646 2489-2505/? I/MainActivity: Action1: String:A
05-18 21:21:44.647 2489-2505/? I/MainActivity: Action1: String:B
05-18 21:21:44.647 2489-2505/? I/MainActivity: Action1: String:C
05-18 21:21:44.648 2489-2505/? I/MainActivity: Action1: String:D
05-18 21:21:44.648 2489-2505/? I/MainActivity: Action1: String:E
05-18 21:21:44.648 2489-2505/? I/MainActivity: Action1: String:F

concat：将多个Observable发射的数据进行合并，而且不会乱序：

 Observable<String> obs1 = Observable.just("A", "B", "C").subscribeOn(Schedulers.io());
        Observable<String> obs2 = Observable.just("D", "E", "F").subscribeOn(Schedulers.io());
        Observable<String> obs3 = Observable.just("G", "H", "I");
        Observable.concat(obs1,obs2,obs3).subscribe(new Action1<String>() {
            @Override
            public void call(String s) {
                Log.i(TAG, "Action1: String:" + s);
            }
        });

05-18 21:28:06.152 2592-2606/? I/MainActivity: Action1: String:A
05-18 21:28:06.152 2592-2606/? I/MainActivity: Action1: String:B
05-18 21:28:06.152 2592-2606/? I/MainActivity: Action1: String:C
05-18 21:28:06.152 2592-2606/? I/MainActivity: Action1: String:D
05-18 21:28:06.152 2592-2606/? I/MainActivity: Action1: String:E
05-18 21:28:06.152 2592-2606/? I/MainActivity: Action1: String:F
05-18 21:28:06.152 2592-2606/? I/MainActivity: Action1: String:G
05-18 21:28:06.152 2592-2606/? I/MainActivity: Action1: String:H
05-18 21:28:06.152 2592-2606/? I/MainActivity: Action1: String:I

zip：合并两个或多个Observable发射出的数据项，根据指定的函数变换他们，并发射一个新值。

Observable<String> obs1 = Observable.just("A", "B", "C").subscribeOn(Schedulers.io());
        Observable<String> obs2 = Observable.just("D", "E", "F").subscribeOn(Schedulers.io());
        Observable.zip(obs1, obs2, new Func2<String, String, String>() {
            @Override
            public String call(String s, String s2) {
                return s + s2;
            }
        }).subscribe(new Action1<String>() {
            @Override
            public void call(String s) {
                Log.d(TAG, "zip: " + s);
            }
        });

05-18 22:50:14.022 3063-3079/com.best.testrxjava D/MainActivity: zip: AD
05-18 22:50:14.022 3063-3079/com.best.testrxjava D/MainActivity: zip: BE
05-18 22:50:14.022 3063-3079/com.best.testrxjava D/MainActivity: zip: CF

combineLastest：

Observable<String> obs1 = Observable.just("A", "B", "C").subscribeOn(Schedulers.io());
        Observable<String> obs2 = Observable.just("D", "E", "F").subscribeOn(Schedulers.io());
        Observable.combineLatest(obs1, obs2, new Func2<String, String, String>() {
            @Override
            public String call(String s, String s2) {
                return s + s2;
            }
        }).subscribe(new Action1<String>() {
            @Override
            public void call(String s) {
                Log.d(TAG, "combineLatest: " + s);
            }
        });

05-18 22:56:52.381 3241-3258/com.best.testrxjava D/MainActivity: combineLatest: CD
05-18 22:56:52.381 3241-3258/com.best.testrxjava D/MainActivity: combineLatest: CE
05-18 22:56:52.381 3241-3258/com.best.testrxjava D/MainActivity: combineLatest: CF

说明：与zip不同的是：

combineLastest结合最新的数进行合并，比如obs1中的"C"是最近发射的，最近发射的和obs2中的所有数据进行合并。
zip指的是多个Observable的合并处理，而combineLastest指的是两个Observable的合并处理。

3. 推荐博客：

如果Recyclerview基础不太好，欢迎跳转阅读 https://www.jianshu.com/p/3eb81f50f4db

4. 后续

如果大家喜欢这篇文章，欢迎点赞；如果想看更多前端移动端后端Java或Python方面的技术，欢迎关注！

看完不懂Rxjava我跪搓板（3）

0. 为了月薪1.8万

1. 序言

2. 组合操作符

3. 推荐博客：

4. 后续

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