springboot 启动报错：required a bean of type 'xxxRepository' that could not be found

springboot启动的时候报错，错误如下：

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：

由于搭建的springboot项目是分模块搭建的，使用的是spring-data-jpa

com.ge.dao.DemoRepository是在ge-springboot-dao模块下。代码如下

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

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

com.ge.MainApplication

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

看错误信息的意思是spring找不到这个bean，也就是扫描不到。

尝试的方法：

1. 在 DemoRepository 加注解@Repository，然而好像并没有什么卵用，还是同样的错误。

2. 手动添加一个jpa相关的configuration类，同样没什么卵用。。

参考：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. 把主启动类MainRepository上的exclude= {DataSourceAutoConfiguration.class} 去掉，然后就可以了。

原来为什么加这个参数？因为没有在application.yml或者application.properties中配置spring.datasource.url这个属性，所以启动会报错。

但是后来我配置了数据源相关的属性，应该把exclude= {DataSourceAutoConfiguration.class}去掉，而且spring-data-jpa是操作数据库相关的框架，可能exculde数据源配置导致spring不会自动扫描repository。

 

总结：

这是我出现@autowired失败的原因。可能对别人并不适用。

但是对于springboot多模块project来说，能够@autowired自动注入的前提的，我举个例子来说明

我这里有3个模块：

ge-springboot-dao 模块中有 DemoRepositry

package com.ge.repository;

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

ge-springboot-service 模块中有 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 模块中有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模块能自动注入service模块的bean，service模块能自动注入dao模块的bean，前提就是所有的这些bean所在的java类都要在同一个package下。

可以发现，我这3个bean虽然在不同的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);
  }
}

当然，如果不使用scanBasePackge="com.ge"来指指定扫描的packge也可以，但是要保证springboot主启动类要在所有bean的同级或者上级packge。

比如我的MainApplication就是com.ge这个包下。

 

如果有不同的package需要spring自动扫描，同样可以使用scanBasePackge={"com.ge1","com.ge2","com.ge3"}