Comprehensive Guide to Spring Annotation Development and MyBatis Integration

Spring 3.0 introduced a pure annotation development model that simplifies configuration by replacing XML bean definitions with annotations such as @Component, @Configuration, @Bean, and others.

1. Annotation Development – Annotations are special interfaces extending Annotation, implemented at runtime by dynamic proxy classes. Accessing them via reflection returns a proxy whose invoke method reads values from the memberValues map sourced from the constant pool.

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

3. Derived Annotations – Spring provides @Controller, @Service, and @Repository to differentiate presentation, business, and data layers, complementing the MVC pattern.

4. Pure Annotation Development Mode – All configuration is expressed via annotations. Example configuration class:

@Configuration<br/>@ComponentScan("yu7daily")<br/>public class Config {...}

Bean scope can be controlled with @Scope("prototype") to create non‑singleton instances.

5. Injection Techniques

Automatic wiring with @Autowired (by type).

Qualified injection using @Qualifier("a") together with @Autowired to resolve NoUniqueBeanDefinitionException when multiple beans of the same type exist.

Simple value injection with @Value("hello java") for primitive data, typically used to read configuration properties.

6. Loading Properties Files – Annotate a configuration class with @PropertySource("test.properties") and inject values using @Value("${name}").

7. Spring‑MyBatis Integration – After adding spring-jdbc and mybatis-spring dependencies, configure a data source, create a MyBatis configuration class to obtain a SqlSessionFactory, and import both configurations:

@Configuration<br/>@ComponentScan("yu7daily")<br/>@PropertySource("classpath:jdbc.properties")<br/>@Import({JdbcConfig.class, MybatisConfig.class})<br/>public class SpringConfig {...}

Finally, obtain beans from the application context:

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

The article concludes with a reminder to share the content and join the community for further learning.