Spring Reactor Mono 在返回数据之前等待订阅者完成它的任务答案

【问题标题】：Spring Reactor Mono wait for the subscriber to complete it's task before returning the dataSpring Reactor Mono 在返回数据之前等待订阅者完成它的任务
【发布时间】：2021-10-13 17:37:13
【问题描述】：

我正在尝试使用返回 Mono 的 Spring reactor webclient 执行多个 HTTP 调用。我正在使用 Mono.block() 等待所有单声道完成。这不是等到 subscribe() 完成。

public class UserValidator {

    public Mono<User> getUserSummary(int userId) {
        User user = new User();

        // First Mono
        Mono<Address> address = WebClientUtil.mono(userId, Address.class);
        address.subscribe(adrs -> updateAddress(adrs, user));

        // Second Mono
        Mono<Education> education = WebClientUtil.mono(userId, Education.class);
        education.subscribe(edcn -> updateEducationDeatils(edcn, user));

        Mono.when(address, education).block(); // Blocking the monos to complete

        // Intermittently returning the incomplete data ******************
        return Mono.just(user);
    }

    private void updateAddress(Address adrs, User user) {
        // Do some validations
        // Validations takes 5 to 10 seconds
        user.setAddress(adrs);
    }

    private void updateEducationDeatils(Education education, User user) {
        // Do some validations
        // Validations takes 5 to 10 seconds
        user.setEducation(education);
    }

}

有人可以帮我解决这个问题，以便在 subscribe() 完成后返回更新的用户对象吗？

【问题讨论】：

标签： java spring spring-boot spring-webflux

【解决方案1】：

如果返回值也是Mono，则不应阻止Mono，而是使用zip：

    public Mono<User> getUserSummary(int userId) {
        Mono<Address> addressMono = WebClientUtil.mono(userId, Address.class);
        Mono<Education> educationMono = WebClientUtil.mono(userId, Education.class);

        return Mono.zip(addressMono, educationMono, (address, education) -> {
          User user = new User();
          user.setAddress(address);
          user.setEducation(education);
        });
    }

另外，请确保您的验证也不会被阻止。

【讨论】：