本文整理了Java中reactor.core.publisher.Mono.hasElement()方法的一些代码示例，展示了Mono.hasElement()的具体用法。这些代码示例主要来源于Github/Stackoverflow/Maven等平台，是从一些精选项目中提取出来的代码，具有较强的参考意义，能在一定程度帮忙到你。Mono.hasElement()方法的具体详情如下：
包路径：reactor.core.publisher.Mono
类名称：Mono
方法名：hasElement

Mono.hasElement介绍

[英]Emit a single boolean true if this Mono has an element.
[中]如果此Mono有元素，则发出一个布尔值true。

代码示例

代码示例来源：origin: reactor/reactor-core

@Test
public void hasElementCancel() throws InterruptedException {
  AtomicBoolean cancelled = new AtomicBoolean();
  Mono.just("foo").hide()
    .doOnCancel(() -> cancelled.set(true))
    .log()
    .hasElement()
    .subscribe(v -> {}, e -> {}, () -> {},
        Subscription::cancel);
  assertThat(cancelled.get()).isTrue();
}

代码示例来源：origin: reactor/reactor-core

@Test
public void testHasElementUpstream() throws InterruptedException {
  AtomicReference<Subscription> sub = new AtomicReference<>();
  Mono.just("foo").hide()
    .hasElement()
    .subscribe(v -> {}, e -> {}, () -> {},
        s -> {
          sub.set(s);
          s.request(Long.MAX_VALUE);
        });
  assertThat(sub.get()).isInstanceOf(MonoHasElement.HasElementSubscriber.class);
  assertThat(Scannable.from(sub.get()).scan(Scannable.Attr.PARENT).getClass()).isEqualTo(FluxHide.HideSubscriber.class);
}

代码示例来源：origin: reactor/reactor-core

@Test
public void monoSourceIsNotCancelled() {
  AtomicLong cancelCount = new AtomicLong();
  StepVerifier.create(Mono.just(1)
              .doOnCancel(cancelCount::incrementAndGet)
              .hasElement())
        .expectNext(true)
        .verifyComplete();
  assertThat(cancelCount.get()).isEqualTo(0);
}

代码示例来源：origin: reactor/reactor-core

@Test
public void emptyMonoSource() {
  AssertSubscriber<Boolean> ts = AssertSubscriber.create();
  Mono.empty().hasElement().subscribe(ts);
  ts.assertValues(false)
   .assertComplete()
   .assertNoError();
}

代码示例来源：origin: reactor/reactor-core

@Test
public void emptySourceBackpressured() {
  AssertSubscriber<Boolean> ts = AssertSubscriber.create(0);
  Mono.empty().hasElement().subscribe(ts);
  ts.assertNoValues()
   .assertNotComplete()
   .assertNoError();
  ts.request(1);
  ts.assertValues(false)
   .assertComplete()
   .assertNoError();
}

代码示例来源：origin: com.aol.cyclops/cyclops-reactor

/**
 * @return
 * @see reactor.core.publisher.Mono#hasElement()
 */
public final Mono<Boolean> hasElement() {
  return boxed.hasElement();
}
/**

代码示例来源：origin: apache/james-project

public Mono<Boolean> executeReturnExists(Statement statement) {
    return executeSingleRowReactor(statement)
        .hasElement();
  }
}

代码示例来源：origin: spring-projects/spring-data-r2dbc

@Override
public Mono<Boolean> existsById(Publisher<ID> publisher) {
  return Mono.from(publisher).flatMap(this::findById).hasElement();
}

代码示例来源：origin: org.springframework.data/spring-data-r2dbc

@Override
public Mono<Boolean> existsById(Publisher<ID> publisher) {
  return Mono.from(publisher).flatMap(this::findById).hasElement();
}

代码示例来源：origin: apache/james-project

@Test
void shouldExecuteTheRunnableAndReturnEmpty() {
  Counter counter = new Counter(1);
  Mono<?> reactor = Mono.empty()
      .switchIfEmpty(ReactorUtils.executeAndEmpty(() -> counter.increment(2)))
      .map(FunctionalUtils.toFunction(any -> counter.increment(4)));
  assertThat(reactor.hasElement().block()).isFalse();
  assertThat(counter.getCounter()).isEqualTo(3);
}

代码示例来源：origin: apache/james-project

@Test
void shouldNotExecuteTheRunnableAndReturnTheValue() {
  Counter counter = new Counter(1);
  Mono<?> reactor = Mono.just(42)
      .switchIfEmpty(ReactorUtils.executeAndEmpty(() -> counter.increment(2)))
      .map(FunctionalUtils.toFunction(any -> counter.increment(4)));
  assertThat(reactor.hasElement().block()).isTrue();
  assertThat(counter.getCounter()).isEqualTo(5);
}

代码示例来源：origin: org.springframework.data/spring-data-r2dbc

@Override
public Mono<Boolean> existsById(ID id) {
  Assert.notNull(id, "Id must not be null!");
  String idColumnName = getIdColumnName();
  BindIdOperation select = accessStrategy.selectById(entity.getTableName(), Collections.singleton(idColumnName),
      idColumnName, 10);
  GenericExecuteSpec sql = databaseClient.execute().sql(select);
  BindSpecAdapter<GenericExecuteSpec> wrapper = BindSpecAdapter.create(sql);
  select.bindId(wrapper, id);
  return wrapper.getBoundOperation().as(entity.getJavaType()) //
      .map((r, md) -> r) //
      .first() //
      .hasElement();
}

代码示例来源：origin: spring-projects/spring-data-r2dbc

@Override
public Mono<Boolean> existsById(ID id) {
  Assert.notNull(id, "Id must not be null!");
  String idColumnName = getIdColumnName();
  BindIdOperation select = accessStrategy.selectById(entity.getTableName(), Collections.singleton(idColumnName),
      idColumnName, 10);
  GenericExecuteSpec sql = databaseClient.execute().sql(select);
  BindSpecAdapter<GenericExecuteSpec> wrapper = BindSpecAdapter.create(sql);
  select.bindId(wrapper, id);
  return wrapper.getBoundOperation().as(entity.getJavaType()) //
      .map((r, md) -> r) //
      .first() //
      .hasElement();
}