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Flowable 的 subscribe 方法

public final Disposable subscribe() {
    return subscribe(Functions.emptyConsumer(), Functions.ON_ERROR_MISSING,
            Functions.EMPTY_ACTION, FlowableInternalHelper.RequestMax.INSTANCE);
}

public final Disposable subscribe(Consumer<? super T> onNext) {
    return subscribe(onNext, Functions.ON_ERROR_MISSING,
            Functions.EMPTY_ACTION, FlowableInternalHelper.RequestMax.INSTANCE);
}

public final Disposable subscribe(Consumer<? super T> onNext, Consumer<? super Throwable> onError) {
    return subscribe(onNext, onError, Functions.EMPTY_ACTION,
            FlowableInternalHelper.RequestMax.INSTANCE);
}

public final Disposable subscribe(Consumer<? super T> onNext, Consumer<? super Throwable> onError,
                                  Action onComplete) {
    return subscribe(onNext, onError, onComplete,
            FlowableInternalHelper.RequestMax.INSTANCE);
}

public final Disposable subscribe(Consumer<? super T> onNext, Consumer<? super Throwable> onError,
                                  Action onComplete, Consumer<? super Subscription> onSubscribe) {
    LambdaSubscriber<T> ls = new LambdaSubscriber<T>(onNext, onError, onComplete, onSubscribe);
    subscribe(ls);
    return ls;
}

public final void subscribe(Subscriber<? super T> s) {
    if (s instanceof FlowableSubscriber) {
        subscribe((FlowableSubscriber<? super T>)s);
    } else {
        ObjectHelper.requireNonNull(s, "s is null");
        subscribe(new StrictSubscriber<T>(s));
    }
}

public final void subscribe(FlowableSubscriber<? super T> s) {
    ObjectHelper.requireNonNull(s, "s is null");
    try {
        Subscriber<? super T> z = RxJavaPlugins.onSubscribe(this, s);
        subscribeActual(z);
    } catch (...) {
       ...
    }
}

protected abstract void subscribeActual(Subscriber<? super T> s);

前面四个方法都是调用了通过默认的：

• Functions.emptyConsumer() :

  static final class EmptyConsumer implements Consumer<Object> {
      @Override
      public void accept(Object v) { }
  
      @Override  
      public String toString() {
          return "EmptyConsumer";
      }
  }
  

• Functions.ON_ERROR_MISSING :

  static final class OnErrorMissingConsumer implements Consumer<Throwable> {
      @Override
      public void accept(Throwable error) {
          RxJavaPlugins.onError(new OnErrorNotImplementedException(error));
      }
  }
  

• Functions.EMPTY_ACTION :

  static final class EmptyAction implements Action {
      @Override
      public void run() { }
  
      @Override
      public String toString() {
          return "EmptyAction";
      }
  }
  

• FlowableInternalHelper.RequestMax.INSTANCE :

  public enum RequestMax implements Consumer<Subscription> {
      INSTANCE;
      @Override
      public void accept(Subscription t) throws Exception {
          t.request(Long.MAX_VALUE);
      }
  }
  

调用了subscribe(onNext, onError, onComplete, onSubscribe)，然后将四个参数包装成一个 LambdaSubscriber对象 传递给 子类重写 的 subscribeActual方法。

而 subscribe(Subscriber<? super T> s) 则通过自己传递 实现FlowableSubscriber接口 或者 传递一个Subscriber构造成StrictSubscriber 传递给 子类重写 的 subscribeActual方法。

然后接下来的流程就和 Rxjava之create操作符源码解析 中介绍的类似。

以上。