mybatis MapperFactoryBean模拟

模拟MapperFactoryBean实现对接口的代理,相关代码如下：

@Data
public class PersonInfo {

    private int id;
    private String name;
    private int age;

}

public interface PersonMapper {

    @Results(id = "personMap", value = {@Result(property = "id", column = "id"),
        @Result(property = "name", column = "name"), @Result(property = "age", column = "age")})

    @Select("select * from person where name=#{name}; ")
    public PersonInfo selectByName(String personName);

    @Select("select * from person;")
    @ResultMap(value = "personMap")
    public List<PersonInfo> selectAll();
}

@Retention(RetentionPolicy.RUNTIME)
@Import(MyBeanDefinitionRegistrar.class)
public @interface MyBatisMonitor {}

@Configuration
@ComponentScan(value = "xyz.xxx.demo.config")
@MyBatisMonitor
public class DemoConfig {}

public class MyBeanDefinitionRegistrar implements ImportBeanDefinitionRegistrar {

    @Override
    public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
        BeanDefinitionBuilder beanDefinitionBuilder = BeanDefinitionBuilder.genericBeanDefinition();
        AbstractBeanDefinition beanDefinition = beanDefinitionBuilder.getBeanDefinition();
        beanDefinition.setBeanClass(MyMapperFactoryBean.class);
        beanDefinition.getConstructorArgumentValues().addGenericArgumentValue(PersonMapper.class);
        registry.registerBeanDefinition("personMapper", beanDefinition);
    }

}

public class MyMapperFactoryBean implements FactoryBean, InvocationHandler {

    public Class clazz;

    public MyMapperFactoryBean(Class clazz) {
        this.clazz = clazz;
    }

    @Nullable
    @Override
    public Object getObject() throws Exception {
        return Proxy.newProxyInstance(this.getClass().getClassLoader(), new Class[] {clazz}, this);
    }

    @Nullable
    @Override
    public Class<?> getObjectType() {
        return clazz;
    }

    @Override
    public Object invoke(Object o, Method method, Object[] objects) throws Throwable {
        System.out.println(clazz.getName() + ">>>>>>>>>>>>>>>>>>>>>>>>>>>> proxy invoke!");
        return clazz;
    }
}

public class MybatisDemoApplication {

    public static void main(String[] args) throws Exception {
        AnnotationConfigApplicationContext annotationConfigApplicationContext =
            new AnnotationConfigApplicationContext(DemoConfig.class);
        PersonMapper personMapper = (PersonMapper)annotationConfigApplicationContext.getBean("personMapper");
        System.out.println(">>>>>>>>>");
    }

}

原文地址：https://www.cnblogs.com/leifonlyone/p/12720323.html