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我正在尝试通过教程创建基本的 Axon/Spring 应用程序，但遇到了奇怪的错误，例如：NoHandlerForCommandException: No handler was subscribed to command。Axon 好像看不到@CommandHandler 注解。

这是我的文件：

总计的

@Aggregate
@NoArgsConstructor
public class Account {

    @AggregateIdentifier
    private UUID accountId;
    private Double balance;

    @CommandHandler
    public Account(CreateAccountCommand command) {
        apply(new AccountCreatedEvent(command.getAccountId(), command.getName()));
    }

    @EventSourcingHandler
    protected void on(AccountCreatedEvent event) {
        this.accountId = event.getAccountId();
        this.balance = 0.0;
    } 
}

事件

@AllArgsConstructor
@Getter
public class AccountCreatedEvent {

    private UUID accountId;
    private String name;
}

命令

@Getter
public class CreateAccountCommand {

    @TargetAggregateIdentifier
    private UUID accountId;
    private String name;

    public CreateAccountCommand(UUID accountId, String name) {
        this.accountId = accountId;
        this.name = name;
    }
}

春季启动配置

@SpringBootApplication
public class App {

    @Configuration
    public static class TestConfiguration {
        @Bean
        public EventStorageEngine inMemoryEventStorageEngine() {
            return new InMemoryEventStorageEngine();
        }
    }

    public static void main(String[] args) {
        SpringApplication.run(App.class, args);
    }
}

这就是我发送 cmd 的方式

@Component
public class AppLoader {

    @Autowired
    private CommandGateway cmdGateway;

    @PostConstruct
    public void init() {
        cmdGateway.send(new CreateAccountCommand(UUID.randomUUID(), "test"));
    }
}

我的 build.gradle

buildscript {
    ext {
        springBootVersion = '2.0.5.RELEASE'
    }
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
    }
}

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'org.springframework.boot'
apply plugin: 'io.spring.dependency-management'

group = 'io.yourpoint.nettnews'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = 1.8

repositories {
    mavenCentral()
}

dependencies {
    testCompile group: 'org.axonframework', name: 'axon-test', version: '3.3.5'
    compile group: 'org.axonframework', name: 'axon-spring-boot-starter', version: '3.3.5'
    compile('org.springframework.boot:spring-boot-starter-webflux')
    compileOnly('org.projectlombok:lombok')
    testCompile('org.springframework.boot:spring-boot-starter-test')
    testCompile('io.projectreactor:reactor-test')
}
4

1 回答 1

1

CommandGateway#send()对于 Axon 来说，在 a 中执行调用很可能@PostConstruct为时过早。

就目前而言，所有的命令、事件和查询处理程序通常在所有 bean 都被初始化后注册。将 REST 端点移到CommandGateway#send()后面应该会给您一个足够长的时间框架，以确保所有处理程序都已注册。

所以简而言之，这是一个时间问题，为什么你会得到NoHandlerForCommandException.

我们（在 AxonIQ）看到了在所有处理程序都已注册后立即发送某种应用程序事件的好处。不过那是未来的事情。

希望这可以帮助您@Benjamin！

于 2018-09-26T07:05:07.323 回答