【RxJava】map过程中各个Observable生命周期分析-Toy模板网

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map和flatMap的区别

首先说下map和flatMap的区别，防止有对RxJava还不够熟悉的小伙伴

map的Function指定如何将A转为B
flatMap的Function则指定如何将Observable<A>转为Observable<B>
map和flatMap最终的转换结果都是Observable<B>
flatMap由于可以自己创建Observable，因此更为强大灵活，map比较简单

Observable生命周期测试

下面，我们创建一个Observable，并通过map和flatMap进行多次Observable转换

分别在正常流程和异常流程下，测试map过程中各个Observable的生命周期执行流程


  import io.reactivex.rxjava3.core.Observable;

  @SuppressWarnings("all")
  public class RxJavaMapTest {

      public static class Action {

          public static String A() {
              System.out.println("A Execute");
              return "A";
          }

          public static Observable<String> B() {
              System.out.println("B Execute");
              return Observable.just("B");
          }

          public static Observable<String> C() {
              System.out.println("C Execute");
              //throw new RuntimeException("Error");
              return Observable.just("C");
          }

          public static Observable<String> D() {
              System.out.println("D Execute");
              return Observable.just("D");
          }

          public static Observable<String> E() {
              System.out.println("E Execute");
              return Observable.just("E");
          }
      }

      public static void main(String[] args) {
          Observable.just("")
                  .map(o -> Action.A())
                  .doOnSubscribe(aAction -> {
                      System.out.println("doOnSubscribe A");
                  })
                  .doOnNext(o -> {
                      System.out.println("doOnNext A1");
                  })
                  .doOnNext(o -> {
                      System.out.println("doOnNext A2");
                  })
                  .doOnError(e -> {
                      System.out.println("doOnError A");
                  })
                  .doOnComplete(() -> {
                      System.out.println("doOnComplete A");
                  })
                  .doFinally(() -> {
                      System.out.println("doOnFinally A");
                  })
                  .flatMap(o -> Action.B())
                  .doOnSubscribe(aAction -> {
                      System.out.println("doOnSubscribe B");
                  })
                  .doOnNext(o -> {
                      System.out.println("doOnNext B");
                  })
                  .doOnError(e -> {
                      System.out.println("doOnError B");
                  })
                  .doOnComplete(() -> {
                      System.out.println("doOnComplete B");
                  })
                  .doFinally(() -> {
                      System.out.println("doOnFinally B");
                  })
                  .flatMap(o -> Action.C())
                  .doOnSubscribe(o -> {
                      System.out.println("doOnSubscribe C");
                  })
                  .doOnNext(o -> {
                      System.out.println("doOnNext C");
                  })
                  .doOnError(e -> {
                      System.out.println("doOnError C");
                  })
                  .doOnComplete(() -> {
                      System.out.println("doOnComplete C");
                  })
                  .doFinally(() -> {
                      System.out.println("doOnFinally C");
                  })
                  .flatMap(o -> Action.D())
                  .doOnSubscribe(o -> {
                      System.out.println("doOnSubscribe D");
                  })
                  .doOnNext(o -> {
                      System.out.println("doOnNext D");
                  })
                  .doOnError(e -> {
                      System.out.println("doOnError D");
                  })
                  .doOnComplete(() -> {
                      System.out.println("doOnComplete D");
                  })
                  .doFinally(() -> {
                      System.out.println("doOnFinally D");
                  })
                  .flatMap(o -> Action.E())
                  .doOnSubscribe(o -> {
                      System.out.println("doOnSubscribe E");
                  })
                  .doOnNext(o -> {
                      System.out.println("doOnNext E");
                  })
                  .doOnError(e -> {
                      System.out.println("doOnError E");
                  })
                  .doOnComplete(() -> {
                      System.out.println("doOnComplete E");
                  })
                  .doFinally(() -> {
                      System.out.println("doOnFinally E");
                  })
                  .subscribe(
                          o -> System.out.println("doOnFinally X"),
                          e -> System.out.println("doOnError X"),
                          () -> System.out.println("doOnFinally X")
                  );
          System.out.println("Task Finish");
      }

  }

正常情况下的运行结果

doOnSubscribe A
doOnSubscribe B
doOnSubscribe C
doOnSubscribe D
doOnSubscribe E
A Execute
doOnNext A1
doOnNext A2
B Execute
doOnNext B
C Execute
doOnNext C
D Execute
doOnNext D
E Execute
doOnNext E
doOnFinally X
doOnComplete A
doOnComplete B
doOnComplete C
doOnComplete D
doOnComplete E
doOnFinally X
doOnFinally E
doOnFinally D
doOnFinally C
doOnFinally B
doOnFinally A
Task Finish

C发生异常时的运行结果

doOnSubscribe A
doOnSubscribe B
doOnSubscribe C
doOnSubscribe D
doOnSubscribe E
A Execute
doOnNext A1
doOnNext A2
B Execute
doOnNext B
C Execute
doOnFinally A
doOnFinally B
doOnError C
doOnFinally C
doOnError D
doOnFinally D
doOnError E
doOnError X
doOnFinally E
Task Finish

下面，我们基于以上两次运行结果进行分析

如果有其它更深层次的疑问，可以复制以上代码，自己调整继续运行文章来源地址https://www.toymoban.com/news/detail-745717.html