Spring注解

  • Z时代
  • 2024-01-10
  • 分类：综合

编程

bean生产

@Bean

@Configuration // 配置类==配置文件,告诉Spring这是一个配置类 
public class MainConfig {
    // 给容器注册一个Bean;类型为返回值的类型,id默认用方法名作为id
    @Bean("PersonX")
    public Person person(){
        return new Person("lisi",20);
    }
}

    @Test
    public void test01(){
        ApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfig.class);
        Person person1 = applicationContext.getBean(Person.class);
        System.out.println(person1);
        Person person2 = (Person) applicationContext.getBean("PersonX");
        System.out.println(person2);
    }

@ComponentScan

  1. 包扫描，只要标注了@Controller、@Service、@Repository、@Component都会被扫描加进容器，bean的id为类名首字母小写

@Configuration
@ComponentScan(value = "cn.ccb")
public class MainConfig {
}

@Test
public void test02(){
    ApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfig.class);
    String[] names = applicationContext.getBeanDefinitionNames();
    for (String name : names) {
        System.out.println(name);
    }
}

结果：

mainConfig
bookController
bookDao
bookService

  1. 包扫描，排除 excludeFilters

@Configuration
@ComponentScan(value = "cn.ccb",excludeFilters = {@ComponentScan.Filter(type = FilterType.ANNOTATION,classes={Controller.class,Service.class})})
public class MainConfig {
}

@Test
public void test02(){
    // 将上面test02()代码粘贴在此处
}

结果：

mainConfig
bookDao

  1. 包扫描，包括 includeFilters

@Configuration
@ComponentScan(value = "cn.ccb",includeFilters = {@ComponentScan.Filter(type = FilterType.ANNOTATION,classes={Controller.class,Service.class})},useDefaultFilters=false)
public class MainConfig {
}

@Test
public void test02(){
    // 将上面test02()代码粘贴在此处
}

结果：

mainConfig
bookController
bookService

@Scope

@Configuration
public class MainConfig {
    // singleton：单实例的（默认值）,ioc容器启动就会调用方法创建对象放到ioc容器中
    // prototype：多实例的,ioc容器启动并不会调用方法创建对象放在容器中，每次获取的时候才会调用方法创建对象
    @Scope("prototype")
    @Bean
    public Person person(){
        return new Person("张三",22);
    }
}

@Import

@Configuration
@Import({Color.class,Red.class})  //导入组件,id默认是组件的全类名
public class MainConfig {
}

结果：

cn.ccb.entities.Color
cn.ccb.entities.Red

bean赋值

@Value

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Person {
    @Value("四川妹子")
    private String name;
    @Value("1234")
    private int age;
}

@Configuration
public class MainConfigOfPropertyValues {
    @Bean
    public Person person(){
        return new Person();
    }
}

@Test
public void test1(){
    AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfigOfPropertyValues.class);
    Object person = applicationContext.getBean("person");
    System.out.println(person);
}

结果：

Person(name=四川妹子, age=1234)

@Autowired

@Service
public class BookService {
    /**
     * @Autowired：自动注入
     * 1、默认按照类型去容器中找对应组件：applicationContext.getBean(BookController.class);
     * 2、如果有多个相同类型的组件，再将变量名作为组件的id去容器中查找
     * @Qualifier：指定需要装配的组件的id
     */
    @Autowired
    private BookController bookController;
}

@Resource

@Service
public class BookService {
    /**
     * @Resource可以和@Autowired一样实现自动装配功能,默认按照变量名作为组件的id去容器中查找
     * 不支持@Primary功能和@Autowired(required=false)
     * @Autowired：spring定义的,@Resource是java规范
     */
    @Resource(name = "InnerConfig")
    private BookController bookController;
}

FactoryBean

// 创建一个FactoryBean
public class ColorFactoryBean implements FactoryBean<Color> {
    public Color getObject() throws Exception {
        System.out.println("调用了----------");
        return new Color();
    }
    public Class<?> getObjectType() {
        return Color.class;
    }
    public boolean isSingleton() {
        return false;
    }
}

@Configuration
public class MainConfig {
    @Bean
    public ColorFactoryBean colorFactoryBean(){
        return new ColorFactoryBean();
    }
}

@Test
public void test03(){
    /**
         * Spring提供的FactoryBean：
         * 默认获取到的是工厂Bean调用getObject()创建的对象
         * 要获取工厂Bean本身,需要在bean的id前加一个& ---> &colorFactoryBean
         */
    AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfig.class);
    Object bean = applicationContext.getBean("colorFactoryBean");
    System.out.println(bean.getClass());  // class cn.ccb.entities.Color
    Object bean2 = applicationContext.getBean("&colorFactoryBean");
    System.out.println(bean2.getClass()); // class cn.ccb.entities.ColorFactoryBean
}

以上是 Spring注解 的全部内容， 来源链接： utcz.com/z/519128.html

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