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springwebflux“只允许一个连接接收订户”,如果switchiffempty返回服务器响应

project-reactor spring-webflux spring-boot spring

kj007 XdebugX · 技术社区 · 6 年前

我想把一个情况下,如果对象存在,然后发送错误,如果没有,然后创建新的用户。

public Mono<ServerResponse> createUser(ServerRequest request) {
        Mono<UserBO> userBOMono = request.bodyToMono(UserBO.class);
        Mono<String> email = userBOMono.map(UserBO::getEmail);
        Mono<User> userMono = email.flatMap(userRepository::findByEmail);
        return userMono.flatMap(user -> {
            Mono<ErrorResponse> errorResponseMono = errorHanlder.handleEmailAlreadyExist();
            return ServerResponse.status(HttpStatus.CONFLICT)
                    .contentType(MediaType.APPLICATION_JSON)
                    .body(errorResponseMono, ErrorResponse.class);
        }).switchIfEmpty(Mono.defer(() -> {
            Mono<User> newUserMono = userBOMono.flatMap(userMapping::mapUserBOToUser);
            Mono<User> dbUserMono = newUserMono.flatMap(userRepository::save);
            return ServerResponse.status(HttpStatus.CREATED)
                    .contentType(MediaType.APPLICATION_JSON)
                    .body(dbUserMono, User.class);

        }));

如果Mono不是空的,那么它的返回与我想要的冲突,如果是空的,那么创建新的,但是它抛出下面的错误:

java.lang.IllegalStateException: Only one connection receive subscriber allowed.
    at reactor.ipc.netty.channel.FluxReceive.startReceiver(FluxReceive.java:276) ~[reactor-netty-0.7.8.RELEASE.jar:0.7.8.RELEASE]
    at reactor.ipc.netty.channel.FluxReceive.lambda$subscribe$2(FluxReceive.java:127) ~[reactor-netty-0.7.8.RELEASE.jar:0.7.8.RELEASE]
    at io.netty.util.concurrent.AbstractEventExecutor.safeExecute$$$capture(AbstractEventExecutor.java:163) ~[netty-common-4.1.27.Final.jar:4.1.27.Final]
    at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java) ~[netty-common-4.1.27.Final.jar:4.1.27.Final]
    at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:404) ~[netty-common-4.1.27.Final.jar:4.1.27.Final]
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:464) ~[netty-transport-4.1.27.Final.jar:4.1.27.Final]
    at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:884) ~[netty-common-4.1.27.Final.jar:4.1.27.Final]
    at java.lang.Thread.run(Thread.java:748) ~[na:1.8.0_131]

更新说明:其正确行为符合方法定义:

switchIfEmpty(Mono<? extends T> alternate)
Fallback to an alternative Mono if this mono is completed without data

意味着当我把空的单核细胞送入体内时,它的工作正常:

return ServerResponse.status(HttpStatus.CREATED)
                    .contentType(MediaType.APPLICATION_JSON)
                    .body(Mono.empty(), User.class);

所以,如果我想发送Mono对象作为返回,那么处理swtichIfEmpty情况的解决方案是什么呢。

2 回复 | 直到 6 年前

kj007 XdebugX 6 年前

最后我解决了这个问题,我读了两次userBOMono流,这导致webflux抛出这个错误。

 public Mono<ServerResponse> createUser(ServerRequest request) {
        Mono<UserBO> userBOMono = request.bodyToMono(UserBO.class);
        return userBOMono.flatMap(userBO -> {
            String email = userBO.getEmail();
            Mono<User> userMono = userRepository.findByEmail(email);
            return userMono.flatMap(user -> errorHandler.handleEmailAlreadyExist())
                    .switchIfEmpty(Mono.defer(() -> createNewUser(userBO)));
        });
    }

    private Mono<ServerResponse> createNewUser(UserBO userBO) {
        Mono<User> userMono = Mono.just(userBO).flatMap(userMapping::mapUserBOToUser).flatMap(userRepository::save);
        return ServerResponse.ok().contentType(MediaType.APPLICATION_JSON)
                .body(userMono, User.class);

    }

cs95 abhishek58g 5 年前

我假设您使用WebClient来调用这个API。