纯编程式驱动IOC

编程式创建bean

public static void main(String[] args) throws Exception {
    AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
    BeanDefinition personDefinition = BeanDefinitionBuilder.rootBeanDefinition(Person.class).getBeanDefinition();
    ctx.registerBeanDefinition("person", personDefinition);
    ctx.refresh();
    Person person = ctx.getBean(Person.class);
    System.out.println(person);
}

编程式依赖注入

public class ProgrammaticInjectApplication {
    
    public static void main(String[] args) throws Exception {
        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
        BeanDefinition personDefinition = BeanDefinitionBuilder.rootBeanDefinition(Person.class)
            .addPropertyValue("name", "老王").getBeanDefinition();
    ctx.registerBeanDefinition("laowang", personDefinition);
    
    BeanDefinition catDefinition = BeanDefinitionBuilder.rootBeanDefinition(Cat.class)
            .addPropertyValue("name", "咪咪").addPropertyReference("person", "laowang")
            .getBeanDefinition();
    ctx.registerBeanDefinition("mimi", catDefinition);
        ctx.refresh();
        Cat cat = ctx.getBean(Cat.class);
        System.out.println(cat);
    }
}

refresh 方法会触发 单实例bean 的实例化

包扫描器ClassPathBeanDefinitionScanner:

public static void main(String[] args) throws Exception {
    AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();

    BeanDefinition personDefinition = BeanDefinitionBuilder.rootBeanDefinition(Person.class)
            .addPropertyValue("name", "老王").getBeanDefinition();
    ctx.registerBeanDefinition("laowang", personDefinition);

    ClassPathBeanDefinitionScanner scanner = new ClassPathBeanDefinitionScanner(ctx);
    scanner.addIncludeFilter((metadataReader, metadataReaderFactory) -> {
        return metadataReader.getClassMetadata().getSuperClassName().equals(Animal.class.getName());
    });
    
    // int count = scanner.scan("com.linkedbear.spring.programmatic.b_di.bean");
    Set<BeanDefinition> animalDefinitions = scanner
            .findCandidateComponents("com.linkedbear.spring.programmatic.b_di.bean");
    animalDefinitions.forEach(definition -> {
        MutablePropertyValues propertyValues = definition.getPropertyValues();
        String beanClassName = definition.getBeanClassName();
        propertyValues.addPropertyValue("name", beanClassName);
        propertyValues.addPropertyValue("person", new RuntimeBeanReference("laowang"));
        ctx.registerBeanDefinition(Introspector.decapitalize(beanClassName.substring(beanClassName.lastIndexOf("."))), definition);
    });
    
    ctx.refresh();

    Cat cat = ctx.getBean(Cat.class);
    System.out.println(cat);
}

xml配置文件解析器XmlBeanDefinitionReader:

 XmlBeanDefinitionReader reader = new XmlBeanDefinitionReader(ctx);
 reader.loadBeanDefinitions(new ClassPathResource("programmatic/programmatic-components.xml"));