Springboot整合Hibernate拦截器时无法向拦截器注入Bean

摘要：同时注释配置失败的构造方法触发了两次，添加到中的实例和注册到容器中的实例并不是同一个实例解决方法增加一个获取的实例的工具类，通过这个工具类调用需要注入的服务的方法工具类修改拦截器执行结果

JDK 1.8

Springboot 2.1.1.RELEASE

    
        org.springframework.boot
        spring-boot-starter-parent
        2.1.1.RELEASE
         
    
    
    
        
            org.springframework.boot
            spring-boot-starter-data-jpa
        

        
            mysql
            mysql-connector-java
            8.0.13
        

        
            org.springframework.boot
            spring-boot-starter-test
            test
        
    

@Entity
public class User implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;

    private String name;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

public interface UserRepository extends JpaRepository {

}

@Service
public class MyService {

    public void print(){
        System.out.println(this.getClass().getSimpleName()+" call");
    }
}

public class SimpleInterceptor extends EmptyInterceptor {

    @Resource
    private MyService myService;

    @Override
    public String onPrepareStatement(String sql) {
        myService.print();
        System.out.println("sql:"+sql);
        return super.onPrepareStatement(sql);
    }
}

@SpringBootApplication
public class BootHibernateInterceptorProblemApplication {

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

}

## DataSource
spring.datasource.url=jdbc:mysql://localhost:3306/demo?characterEncoding=utf8&useSSL=true
spring.datasource.username=root
spring.datasource.password=123456789

## hibernate
spring.jpa.hibernate.ddl-auto=update
## add interceptor
spring.jpa.properties.hibernate.ejb.interceptor=com.rjh.interceptor.SimpleInterceptor

@RunWith(SpringRunner.class)
@SpringBootTest
public class BootHibernateInterceptorProblemApplicationTests {

    @Resource
    private UserRepository userRepository;

    @Test
    public void contextLoads() {
        System.out.println(userRepository.findAll());
    }

}

java.lang.NullPointerException
    at com.rjh.interceptor.SimpleInterceptor.onPrepareStatement(SimpleInterceptor.java:20)
    ...
    ...
    ...

根据异常信息，猜测是注入MyService失败

@RunWith(SpringRunner.class)
@SpringBootTest
public class BootHibernateInterceptorProblemApplicationTests {

    @Resource
    private UserRepository userRepository;

    @Resource
    private MyService myService;

    @Resource
    private SimpleInterceptor simpleInterceptor;

    @Test
    public void contextLoads() {
        Assert.assertNotNull(myService);
        Assert.assertNotNull(simpleInterceptor);
        System.out.println(userRepository.findAll());
    }

}

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type "com.rjh.interceptor.SimpleInterceptor" available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@javax.annotation.Resource(shareable=true, lookup=, name=, description=, authenticationType=CONTAINER, type=class java.lang.Object, mappedName=)}
    ...

根据异常信息可知，Spring的IoC容器中并没有SimpleInterceptor这个Bean，从此处可知spring.jpa.properties.hibernate.ejb.interceptor=com.rjh.interceptor.SimpleInterceptor并没有把这个拦截器注册到Spring容器中

在SimpleInterceptor上添加@Component注解，将SimpleInterceptor注册到Spring容器中。同时注释spring.jpa.properties.hibernate.ejb.interceptor配置

失败：SimpleInterceptor的构造方法触发了两次，添加到Hibernate中的SimpleInterceptor实例和注册到Spring容器中的SimpleInterceptor实例并不是同一个实例

增加一个获取Spring的ApplicationContext实例的工具类，通过这个工具类调用需要注入的服务的方法

@Component
public class SpringContextUtil implements ApplicationContextAware {

    private static ApplicationContext applicationContext;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        SpringContextUtil.applicationContext=applicationContext;
    }

    public static ApplicationContext getApplicationContext() {
        return applicationContext;
    }
}

public class SimpleInterceptor extends EmptyInterceptor {

    @Override
    public String onPrepareStatement(String sql) {
        MyService myService= SpringContextUtil.getApplicationContext().getBean(MyService.class);
        myService.print();
        System.out.println("sql:"+sql);
        return super.onPrepareStatement(sql);
    }

}

MyService call
sql:select user0_.id as id1_0_, user0_.name as name2_0_ from user user0_
[]