Spring Annotation Development and MyBatis Integration Guide

Preface

Spring 3.0 introduced a pure annotation development mode that further simplifies configuration, especially when integrating with MyBatis.

1. Annotation Development

Annotations are special interfaces extending Annotation, implemented at runtime by dynamic proxy classes. When retrieving annotations via reflection, a proxy object ( $Proxy1) is returned, and the AnnotationInvocationHandler fetches values from the memberValues map sourced from the constant pool.

2. Defining Beans with Annotations

Before annotations, beans were declared in XML, e.g., <bean id="a" class="yu7daily.Dao.Daoimpl.A"/>. After adopting annotations, the XML <bean> entry is removed and the class is marked with @Component("a").

@Component("a")
public class A implements AA {
    public void save() {
        System.out.println("book dao save ...");
    }
}

Scanning the package with <context:component-scan base-package="yu7daily.Dao"/> registers the component in the IoC container.

3. Derived Annotations

Beyond @Component, Spring provides @Controller, @Service, and @Repository to distinguish presentation, business, and data layers in MVC architecture.

4. Pure Annotation Development Mode

All configuration is moved to annotations. Use @Configuration to declare a configuration class and @ComponentScan to specify the scan path.

@Configuration
@ComponentScan("yu7daily")
public class Config { ... }

Instantiate the context with

ApplicationContext ctx = new AnnotationConfigApplicationContext(Config.class);

to obtain beans.

5. Bean Scope Configuration

Beans are singleton by default; use @Scope("prototype") to create non‑singleton beans.

@Component("a")
@Scope("prototype")
public class A implements AA { ... }

6. Annotation‑Based Injection

Use @Autowired for setter injection, @Qualifier to resolve NoUniqueBeanDefinitionException when multiple candidates exist, and @Value for simple data injection from properties files.

@Service
public class A implements AA {
    @Autowired
    private B b;
}

@Repository("b")
public class B implements BB {
    @Autowired
    @Qualifier("a")
    private AA aa;
}

7. Reading Properties Files

Mark a configuration class with @PropertySource("test.properties") and inject values using @Value("${name}").

@Configuration
@PropertySource("classpath:jdbc.properties")
public class SpringConfig { ... }

8. Spring Integration with MyBatis

Add spring-jdbc and mybatis-spring dependencies, configure the data source, create a MyBatis configuration class to obtain SqlSessionFactory, and retrieve beans from the context to perform data operations.

ApplicationContext ACC = new AnnotationConfigApplicationContext(SpringConfig.class);
AccountService acc = ACC.getBean(AccountService.class);

The article concludes with a reminder that annotation‑based configuration dramatically reduces boilerplate compared to XML.