java - 如何通过实现自动连接接口(interface)

Question

我已经在谷歌上搜索答案很长时间了，但我确信我错过了一些将这一切结合在一起的东西。我只是不确定是什么。运行 Spring 服务器失败并出现错误:

    org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'testController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.test.abc.sv.dao.TestDAO com.test.abc.sv.controller.TestController.testDao; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.test.abc.sv.dao.TestDAO] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:293)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1186)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:302)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:298)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:706)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:762)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:482)
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:109)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:691)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:320)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:952)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:941)
    at com.test.abc.sv.SpringLaunch.main(SpringLaunch.java:26)
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.test.abc.sv.dao.TestDAO com.test.abc.sv.controller.TestController.testDao; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.test.abc.sv.dao.TestDAO] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:509)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:290)
    ... 16 common frames omitted
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.test.abc.sv.dao.TestDAO] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:1118)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:967)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:862)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:481)
    ... 18 common frames omitted

Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'testController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.test.abc.sv.dao.TestDAO com.test.abc.sv.controller.TestController.testDao; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.test.abc.sv.dao.TestDAO] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:293)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1186)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:302)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:298)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:706)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:762)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:482)
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:109)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:691)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:320)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:952)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:941)
    at com.test.abc.sv.SpringLaunch.main(SpringLaunch.java:26)
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.test.abc.sv.dao.TestDAO com.test.abc.sv.controller.TestController.testDao; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.test.abc.sv.dao.TestDAO] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:509)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:290)
    ... 16 more
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.test.abc.sv.dao.TestDAO] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:1118)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:967)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:862)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:481)
    ... 18 more

所以我正在运行该应用程序SpringLaunch.class - com.test.abc.sv

@Configuration
@ComponentScan
@EnableAutoConfiguration
public class SpringLaunch extends SpringBootServletInitializer{

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

@Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
    return application.sources(applicationClass);
}

private static Class<SpringLaunch> applicationClass = SpringLaunch.class;

    @Bean
    public DataSource dataSource() {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName("oracle.jdbc.driver.OracleDriver");
        dataSource.setUrl("jdbc:oracle:thin:@(DESCRIPTION ="
                                            +"(LOAD_BALANCE=on)"
                                            +"(FAILOVER=on)"
                                            +"(ADDRESS=(PROTOCOL=tcp)(HOST=56.276.152.217)(PORT=1521))"
                                            +"(ADDRESS=(PROTOCOL=tcp)(HOST=56.276.152.218)(PORT=1521))"
                                            +"(CONNECT_DATA=(SERVICE_NAME=test.abc.com)))");
        dataSource.setUsername("DevUser");
        dataSource.setPassword("Credential");

        return dataSource;
    }

    @Bean
    public TestDAO testDAO() {
        return new TestDAOImpl(dataSource());
    }

}

TestController.class - com.test.abc.sv.controller

    @RestController
@RequestMapping("/test")
public class TestController{


    @Autowired
    TestDAO testDao;

    final static Logger logger = Logger.getLogger(TestController.class);

    @RequestMapping(value="/setup", method = RequestMethod.GET)
    public Message setupTest(@RequestParam(value="id", required=true) String testNumber) {
        String testMsg = new String(); 

        try{
            testMsg = testDao.prepDatabase(testNumber);
        }
        catch(SQLException e)
        {
            //Log e.getMessage();
            logger.error(e.getMessage());
            System.out.println(e.getMessage());
            return new Message("-1");
        }

        return new Message(testMsg);
    }

    @RequestMapping(value="/teardown", method = RequestMethod.GET)
    public Message teardownTest(@RequestParam(value="id", required=true) String testNumber) {
        String testMsg = new String(); 

        try{
            testMsg = testDao.removeTestData(testNumber);
        }
        catch(SQLException e)
        {
            //Log e.getMessage();
            logger.error(e.getMessage());
            System.out.println(e.getMessage());
            return new Message("-1");
        }

        return new Message(testMsg);
    }

}

TestDAO.class - com.test.abc.sv.dao 接口(interface)

 public interface TestDAO {

    public String prepDatabase(String testNumber)
            throws SQLException;

    public String removeTestData(String testNumber)
            throws SQLException;

}

`TestDAOImpl.class - com.test.abc.sv.dao'

    @Component
public class TestDAOImpl implements TestDAO{

    private Log log = LogFactory.getLog(TestDAOImpl.class);

    private JdbcTemplate jdbcTemplate;

    public TestDAOImpl(DataSource dataSource) {
        jdbcTemplate = new JdbcTemplate(dataSource);
    }

    @Override
    public String prepDatabase(String testNumber)
            throws SQLException {

        //Impl Stuff

    }

    @Override
    public String removeTestData(String testNumber)
            throws SQLException {

        //Impl Stuff
    } 

}

Answer 1

来自documentation @ComponentScan:

If specific packages are not defined scanning will occur from the package of the class with this annotation.

根据您的问题，您的 Application 类位于 com.test.abc.sv.controller 包中。因此，com.test.abc.sv.controller 及其子包中的所有内容都将被扫描，但这不包括您的自定义配置或服务，因为它们不在 com.test 的支持中.abc.sv.controller.

因此，解决方案是将 Application 类移动到 com.test.abc 包，或者显式定义要扫描的包为 com.test例如.abc。

此外，我不太确定您为什么使用该自定义配置类。您可以使用 Spring Boot properties 配置数据源.

至于配置类中的 DAO/service bean 声明，这就是 service 和 dao 的 @Service 或 @Repository 注释的用途。所以我建议也摆脱这些。如果不这样做，您很可能会遇到另一个异常，因为您的 bean 将通过组件扫描注册一次，并从您的配置类注册第二次，这将导致 NoUniqueBeanDefinitionException .