springboot 啟動報錯：required a bean of type 'xxxRepository' that could not be found

springboot啟動的時候報錯，錯誤如下：

Field demoRepository in com.ge.serviceImpl.DemoServiceImpl required a bean of type 'com.ge.dao.DemoRepository' that could not be found.

The injection point has the following annotations:
    - @org.springframework.beans.factory.annotation.Autowired(required=true)

Action:

Consider defining a bean of type 'com.ge.dao.DemoRepository' in your configuration.

原因分析：

由於搭建的springboot項目是分模塊搭建的，使用的是spring-data-jpa

com.ge.dao.DemoRepository是在ge-springboot-dao模塊下。代碼如下

public interface DemoRepository extends JpaRepository<Demo, Integer> {}

但是SpringBootApplication是在ge-springboot-web這個module下。

com.ge.MainApplication

@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})
public class MainApplication {
  public static void main(String[] args) {
    SpringApplication.run(MainApplication.class, args);
  }
}

看錯誤信息的意思是spring找不到這個bean，也就是掃描不到。

嘗試的方法：

1. 在 DemoRepository 加注解@Repository，然而好像並沒有什么卵用，還是同樣的錯誤。

2. 手動添加一個jpa相關的configuration類，同樣沒什么卵用。。

參考：https://stackoverflow.com/questions/46315919/spring-boot-2-0-0-m4-required-a-bean-named-entitymanagerfactory-that-could-not

@Configuration
@ComponentScan(basePackages = "com.ge")
@EnableJpaRepositories(
    basePackages = "com.ge",
    entityManagerFactoryRef = "entityManagerFactory",
    transactionManagerRef = "transactionManager")
@EnableTransactionManagement
public class DaoConfiguration {

  @Autowired private Environment environment;

  @Value("${datasource.sampleapp.maxPoolSize:10}")
  private int maxPoolSize;

  /*
   * Populate SpringBoot DataSourceProperties object directly from
  application.yml
   * based on prefix.Thanks to .yml, Hierachical data is mapped out of
  the box with matching-name
   * properties of DataSourceProperties object].
   */
  @Bean
  @Primary
  @ConfigurationProperties(prefix = "spring.datasource")
  public DataSourceProperties dataSourceProperties() {
    return new DataSourceProperties();
  }

  /*
   * Configure HikariCP pooled DataSource.
   */
  @Bean
  public DataSource dataSource() {
    DataSourceProperties dataSourceProperties = dataSourceProperties();
    HikariDataSource dataSource =
        (HikariDataSource)
            org.springframework.boot.jdbc.DataSourceBuilder.create(
                    dataSourceProperties.getClassLoader())
                .driverClassName(dataSourceProperties.getDriverClassName())
                .url(dataSourceProperties.getUrl())
                .username(dataSourceProperties.getUsername())
                .password(dataSourceProperties.getPassword())
                .type(HikariDataSource.class)
                .build();
    dataSource.setMaximumPoolSize(maxPoolSize);
    return dataSource;
  }

  /*
   * Entity Manager Factory setup.
   */
  @Bean
  public LocalContainerEntityManagerFactoryBean entityManagerFactory() throws NamingException {
    LocalContainerEntityManagerFactoryBean factoryBean =
        new LocalContainerEntityManagerFactoryBean();
    factoryBean.setDataSource(dataSource());
    factoryBean.setPackagesToScan(new String[] {"webroot.websrv"});
    factoryBean.setJpaVendorAdapter(jpaVendorAdapter());
    factoryBean.setJpaProperties(jpaProperties());
    return factoryBean;
  }

  /*
   * Provider specific adapter.
   */
  @Bean
  public JpaVendorAdapter jpaVendorAdapter() {
    HibernateJpaVendorAdapter hibernateJpaVendorAdapter = new HibernateJpaVendorAdapter();
    return hibernateJpaVendorAdapter;
  }

  /*
   * Here you can specify any provider specific properties.
   */
  private Properties jpaProperties() {
    Properties properties = new Properties();
    properties.put(
        "hibernate.dialect",
        environment.getRequiredProperty("spring.jpa.properties.hibernate.dialect"));
    return properties;
  }

  @Bean
  @Autowired
  public PlatformTransactionManager transactionManager(EntityManagerFactory emf) {
    JpaTransactionManager txManager = new JpaTransactionManager();
    txManager.setEntityManagerFactory(emf);
    return txManager;
  }
}

 

3. 把主啟動類MainRepository上的exclude= {DataSourceAutoConfiguration.class} 去掉，然后就可以了。

原來為什么加這個參數？因為沒有在application.yml或者application.properties中配置spring.datasource.url這個屬性，所以啟動會報錯。

但是后來我配置了數據源相關的屬性，應該把exclude= {DataSourceAutoConfiguration.class}去掉，而且spring-data-jpa是操作數據庫相關的框架，可能exculde數據源配置導致spring不會自動掃描repository。

 

總結：

這是我出現@autowired失敗的原因。可能對別人並不適用。

但是對於springboot多模塊project來說，能夠@autowired自動注入的前提的，我舉個例子來說明

我這里有3個模塊：

ge-springboot-dao 模塊中有 DemoRepositry

package com.ge.repository;

public interface DemoRepository extends JpaRepository<Demo, Integer> {}

ge-springboot-service 模塊中有 DemoServiceImpl

package com.ge.service.impl;

@Service
public class DemoServiceImpl implements DemoService {

  @Autowired private DemoRepository demoRepository;

  @Override
  public Demo save(Demo demo) {
    return demoRepository.save(demo);
  }

  @Override
  public Demo get(Integer id) {
    return demoRepository.getOne(id);
  }
}

ge-springboot-web 模塊中有DemoController 和SpringBootApplication

package com.ge.controller;

@Controller
@RequestMapping("/demo")
public class DemoController {

  @Autowired private DemoService demoService;

  @ResponseBody
  @GetMapping("/save")
  public Demo save() {
    Demo demo = new Demo();
    demo.setName("gejunling");
    return demoService.save(demo);
  }
}

web模塊能自動注入service模塊的bean，service模塊能自動注入dao模塊的bean，前提就是所有的這些bean所在的java類都要在同一個package下。

可以發現，我這3個bean雖然在不同的module下，但是所在的packge都是在 com.ge.xxx.xxx

然后在@SpringBootApplication添加scanBasePackge="com.ge"即可。如下

@SpringBootApplication(scanBasePackages = {"com.ge"})
public class MainApplication {
  public static void main(String[] args) {
    SpringApplication.run(MainApplication.class, args);
  }
}

當然，如果不使用scanBasePackge="com.ge"來指指定掃描的packge也可以，但是要保證springboot主啟動類要在所有bean的同級或者上級packge。

比如我的MainApplication就是com.ge這個包下。

 

如果有不同的package需要spring自動掃描，同樣可以使用scanBasePackge={"com.ge1","com.ge2","com.ge3"}