RXJAVA之变换操作

RXJAVA提供了以下变换操作，对Observable的消息进行变换操作：

1.window

定期将来自Observable的数据分拆成一些Observable窗口，然后发射这些窗口，而不是每次发射一项。

Observable<String> observable = Observable.just("123", "456","789","abc");

observable.window(3).subscribeWith(new Observer<Observable<String>>(){

@Override

public void onComplete() {

System.out.println("complete");

}

@Override

public void onError(Throwable arg0) {

System.out.println("error");

}

@Override

public void onNext(Observable<String> arg0) {

arg0.subscribeWith(new Observer<String>(){

@Override

public void onSubscribe(Disposable d) {

System.out.println("onSubscribe");

}

@Override

public void onNext(String t) {

System.out.println(t);

}

@Override

public void onError(Throwable e) {

System.out.println("error");

}

@Override

public void onComplete() {

System.out.println("complete");

}});

}

@Override

public void onSubscribe(Disposable arg0) {

System.out.println("onSubscribe");

}

});

}

输出结果

onSubscribe

onSubscribe

123

456

789

complete

onSubscribe

abc

complete

complete

2.map

变换接收到的数据，重新发放出去。map函数只有一个参数，参数一般是Func1，Func1的<I,O>I,O模版分别为输入和输出值的类型，实现Func1的call方法对I类型进行处理后返回O类型数据。

Observable.just("123", "456","789").map(new Function<String,Integer>(){

@Override

public Integer apply(String t) throws Exception {

return Integer.parseInt(t);

}}).subscribeWith(new Observer<Integer>(){

@Override

public void onSubscribe(Disposable d) {

System.out.println("onSubscribe");

}

@Override

public void onNext(Integer t) {

System.out.println(t);

}

@Override

public void onError(Throwable e) {

System.out.println("onError");

}

@Override

public void onComplete() {

System.out.println("onComplete");

}});

}

输出结果

onSubscribe

123

456

789

onComplete

3.flatmap

将Observable发射的数据变换为Observables集合，然后将这些Observable发射的数据平坦化的放进一个单独的Observable，内部采用merge合并。

Observable<String> observable = Observable.just("123", "456","789","abc");

observable.flatMap(new Function<String,Observable<String>>(){

@Override

public Observable<String> apply(String t) throws Exception {

return Observable.just(t+"flatmap");

}}

).subscribeWith(new Observer<String>(){

@Override

public void onSubscribe(Disposable d) {

System.out.println("onSubscribe");

}

@Override

public void onNext(String t) {

System.out.println(t);

}

@Override

public void onError(Throwable e) {

System.out.println("onError");

}

@Override

public void onComplete() {

System.out.println("onComplete");

}});

}

输出结果

onSubscribe

123flatmap

456flatmap

789flatmap

abcflatmap

onComplete