使用Spring Reactive（R2DBC）与MSSQL连接，创建bean时出错

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我目前正在尝试与Microsoft SQL Server建立数据库连接。不幸的是，我不明白为什么它不起作用。不幸的是，错误消息可能无法给我准确的信息。

入门级

@ComponentScan({ "com.example.web", "com.example.repository", "com.example.config", "com.example.domain" })
@SpringBootApplication
public class R2Dbc3Application {

    public static void main(String[] args) {
        SpringApplication.run(R2Dbc3Application.class, args);
    }

}

数据库配置：

@Configuration
@EnableR2dbcRepositories("com.example.repository")
public class DatabaseConfiguration extends AbstractR2dbcConfiguration {

    private final Logger log = LoggerFactory.getLogger(DatabaseConfiguration.class);

    @Value("${spring.data.mssql.host}")
    private String host;

    @Value("${spring.data.mssql.database}")
    private String database;

    @Value("${spring.data.mssql.username}")
    private String username;

    @Value("${spring.data.mssql.password}")
    private String password;



    @Bean
    @Override
    public MssqlConnectionFactory connectionFactory() {

        System.out.println("Connecting to database" +  host);
        return new MssqlConnectionFactory(MssqlConnectionConfiguration.builder()
                .host(host)
                .port(1453)
                .database(database)
                .username(username)
                .password(password)
                .build());
    }
}

DatabaseInitializer：

@Component
public class DatabaseInitializer {

    private final Logger log = LoggerFactory.getLogger(DatabaseInitializer.class);

    @Autowired
    PersonRepository personRepository;

    public DatabaseInitializer(PersonRepository personRepository) {
        this.personRepository = personRepository;
    }

    @PostConstruct
    public void init() {
        log.info("Initializing database if necessary");
        personRepository.findAll().count().subscribe(count -> {
            if (count == 0) {
                log.info("Database is empty, inserting sample data");
                createPerson("Josh", "Long", "Pivotal");
                createPerson("Julien", "Dubois", "Microsoft");
            } else {
                log.info("Database is already initialized");
            }
        });
    }

    private void createPerson(String firstName, String lastName, String company) {
        Person person = new Person();
        person.setFirstName(firstName);
        person.setLastName(lastName);
        person.setCompany(company);
        personRepository.save(person).log().subscribe();
    }
}

域：

import org.springframework.data.annotation.Id;导入org.springframework.data.relational.core.mapping.Table;

@ Table（“ person”）公共类Person {

@Id
private Long id;

private String firstName;

private String lastName;

private String company;

// getter und setter

存储库：

@Repository
public interface PersonRepository extends ReactiveCrudRepository<Person, Long> {
}

控制器：

@RestController
public class PersonController {

    private final PersonRepository personRepository;

    public PersonController(PersonRepository personRepository) {
        this.personRepository = personRepository;
    }

    @GetMapping(value = "/persons", produces = MediaType.TEXT_EVENT_STREAM_VALUE)
    public Flux<Person> list() {
        return personRepository.findAll();
    }


}

Pom：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.6.RELEASE</version>
        <relativePath /> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>R2DBC2</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>R2DBC2</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-webflux</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-r2dbc</artifactId>
            <version>1.0.0.gh-151-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>io.projectreactor</groupId>
            <artifactId>reactor-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

    <repositories>
        <repository>
            <id>spring-libs-snapshot</id>
            <url>https://repo.spring.io/libs-snapshot</url>
            <snapshots>
                <enabled>true</enabled>
            </snapshots>
        </repository>
        <repository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/milestone</url>
        </repository>
    </repositories>
    <pluginRepositories>
        <pluginRepository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/milestone</url>
        </pluginRepository>
    </pluginRepositories>


</project>

错误信息：

2020-05-25 10:23:35.193  INFO 22532 --- [  restartedMain] com.example.app.R2Dbc3Application        : Starting R2Dbc3Application on 64LP0Z2 with PID 22532 (C:	oolsSpring-Tool-SuiteR2DBC3	argetclasses started by kemal.sacirovic in C:	oolsSpring-Tool-SuiteR2DBC3)
2020-05-25 10:23:35.195  INFO 22532 --- [  restartedMain] com.example.app.R2Dbc3Application        : No active profile set, falling back to default profiles: default
2020-05-25 10:23:35.236  INFO 22532 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : Devtools property defaults active! Set 'spring.devtools.add-properties' to 'false' to disable
2020-05-25 10:23:35.237  INFO 22532 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : For additional web related logging consider setting the 'logging.level.web' property to 'DEBUG'
2020-05-25 10:23:35.555  INFO 22532 --- [  restartedMain] .s.d.r.c.RepositoryConfigurationDelegate : Bootstrapping Spring Data R2DBC repositories in DEFAULT mode.
2020-05-25 10:23:35.588  INFO 22532 --- [  restartedMain] .s.d.r.c.RepositoryConfigurationDelegate : Finished Spring Data repository scanning in 30ms. Found 1 R2DBC repository interfaces.
Connecting to databasedbtbln01
2020-05-25 10:23:35.930  WARN 22532 --- [  restartedMain] onfigReactiveWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'personController' defined in file [C:	oolsSpring-Tool-SuiteR2DBC3	argetclassescomexamplewebPersonController.class]: Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'personRepository': Cannot resolve reference to bean 'databaseClient' while setting bean property 'databaseClient'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'databaseClient' defined in class path resource [com/example/config/DatabaseConfiguration.class]: Unsatisfied dependency expressed through method 'databaseClient' parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'reactiveDataAccessStrategy' defined in class path resource [com/example/config/DatabaseConfiguration.class]: Unsatisfied dependency expressed through method 'reactiveDataAccessStrategy' parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'r2dbcMappingContext' defined in class path resource [com/example/config/DatabaseConfiguration.class]: Unsatisfied dependency expressed through method 'r2dbcMappingContext' parameter 1; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'r2dbcCustomConversions' defined in class path resource [com/example/config/DatabaseConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.data.r2dbc.convert.R2dbcCustomConversions]: Factory method 'r2dbcCustomConversions' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'connectionFactory' defined in class path resource [com/example/config/DatabaseConfiguration.class]: Post-processing of merged bean definition failed; nested exception is java.lang.IllegalStateException: Failed to introspect Class [io.r2dbc.mssql.MssqlConnectionFactory] from ClassLoader [sun.misc.Launcher$AppClassLoader@764c12b6]
2020-05-25 10:23:35.947  INFO 22532 --- [  restartedMain] ConditionEvaluationReportLoggingListener : 

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2020-05-25 10:23:35.956 ERROR 22532 --- [  restartedMain] o.s.boot.SpringApplication               : Application run failed

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'personController' defined in file [C:	oolsSpring-Tool-SuiteR2DBC3	argetclassescomexamplewebPersonController.class]: Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'personRepository': Cannot resolve reference to bean 'databaseClient' while setting bean property 'databaseClient'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'databaseClient' defined in class path resource [com/example/config/DatabaseConfiguration.class]: Unsatisfied dependency expressed through method 'databaseClient' parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'reactiveDataAccessStrategy' defined in class path resource [com/example/config/DatabaseConfiguration.class]: Unsatisfied dependency expressed through method 'reactiveDataAccessStrategy' parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'r2dbcMappingContext' defined in class path resource [com/example/config/DatabaseConfiguration.class]: Unsatisfied dependency expressed through method 'r2dbcMappingContext' parameter 1; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'r2dbcCustomConversions' defined in class path resource [com/example/config/DatabaseConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.data.r2dbc.convert.R2dbcCustomConversions]: Factory method 'r2dbcCustomConversions' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'connectionFactory' defined in class path resource [com/example/config/DatabaseConfiguration.class]: Post-processing of merged bean definition failed; nested exception is java.lang.IllegalStateException: Failed to introspect Class [io.r2dbc.mssql.MssqlConnectionFactory] from ClassLoader [sun.misc.Launcher$AppClassLoader@764c12b6]
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:798) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:228) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1358) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1204) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:557) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:882) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:878) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.boot.web.reactive.context.ReactiveWebServerApplicationContext.refresh(ReactiveWebServerApplicationContext.java:66) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
    at com.example.app.R2Dbc3Application.main(R2Dbc3Application.java:13) [classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_212]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_212]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_212]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_212]
答案

请为DatabaseClient添加一个bean，如下所示 @Bean public DatabaseClient databaseClient() { return create(connectionFactory); }

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