1. @Configuration和@Bean注册组件流程

1.1. 依赖

<properties>
    <spring.version>5.1.5.RELEASE</spring.version>
</properties>

<dependencies>
    <!-- junit -->
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
    </dependency>
    <!-- lombok -->
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.18.6</version>
        <scope>provided</scope>
    </dependency>
    <!-- spring core -->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <!-- spring test -->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-test</artifactId>
        <version>${spring.version}</version>
    </dependency>
</dependencies>

1.2. 编写Bean

// 不需要设置@Component组件注解
@Data
@NoArgsConstructor
@AllArgsConstructor
public class Person {
    private String name;
    private Integer age;
}

1.3. 编写Bean配置类

以前写是Bean配置文件，现在改为Bean配置类

@Configuration // 标识当前类是一个配置类，配置类==配置文件
public class BeanConfig {
    @Bean // 给容器注册一个Bean，方法返回类型作为Bean的类型，方法名作为Bean的id
    public Person person() {
        return new Person("张三", 20);
    }
}

1.4. 编写测试方法

以前创建ClassPathXmlApplicationContext，参数是指定配置文件。
现在创建AnnotationConfigApplicationContext，参数是指定配置类

@Test
public void test() {
    // 创建AnnotationConfigApplicationContext，指定配置类class
    ApplicationContext ioc = new AnnotationConfigApplicationContext(BeanConfig.class);
    Person person = ioc.getBean(Person.class);
    String[] names = ioc.getBeanNamesForType(Person.class);
    System.out.println(person);
    System.out.println(Arrays.toString(names)); // 查看Person在容器中的name
}

2. 给Bean命名

@Bean注解的value或name属性可以给Bean命名

1
2
3

@Bean("person1") 
@Bean(value = "person1")
@Bean(name = "person1")

命名示例

@Configuration
public class BeanConfig {
    @Bean("person1") // 给Bean命名
    public Person person() {
        return new Person("张三", 20);
    }
}