04.SpringBoot容器功能

@Configuration(proxyBeanMethods = true)
public class MyConfig {
    @Bean//默认也是单实例的
    public User user1()
    {
        return  new User("ylc",22);
    }
}

/*这是一个Springboot应用*/
@SpringBootApplication(scanBasePackages = "com.ylc")
public class MainApplication {
    public static void main(String[] args) {
        //返回IOC容器
       ConfigurableApplicationContext context = SpringApplication.run(MainApplication.class,args);
        //从容器中获取组件
        User user1 = context.getBean("user1", User.class);
        User user2 = context.getBean("user1", User.class);
        System.out.println(user1==user2);
    }
}

@Import(DBHelper.class)//给容器中自动创建出这类型的组件、默认组件的名字就是全类名

@ImportResource("classpath:beans.xml")

user.name="小明"
user.age=12

@Component
@ConfigurationProperties(prefix = "user")//user为配置文件的前缀名
public class User {
    public  String name;
    public  int age;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public User(String name, int age) {
        this.name = name;
        this.age = age;
    }
    public User() {
    }
}

@RestController
public class HelloWorldController {
    @Autowired
    User user;
    @RequestMapping("/GetUser")
    public User GetUser()
    {
        return  user;
    }
}

@EnableConfigurationProperties(Car.class)
//1、开启Car配置绑定功能
//2、把这个Car这个组件自动注册到容器中
public class MyConfig {
}

@ConfigurationProperties(prefix = "mycar")
public class Car {
    public  String CarType;
    public  int Price;
    public Car(String carType, int price) {
        CarType = carType;
        Price = price;
    }
    public String getCarType() {
        return CarType;
    }
    public void setCarType(String carType) {
        CarType = carType;
    }
    public double getPrice() {
        return Price;
    }
    public void setPrice(int price) {
        Price = price;
    }
    public Car() {
    }
}

static class Registrar implements ImportBeanDefinitionRegistrar, DeterminableImports {
        public void registerBeanDefinitions(AnnotationMetadata metadata, BeanDefinitionRegistry registry) {
            AutoConfigurationPackages.register(registry, (String[])(new AutoConfigurationPackages.PackageImports(metadata)).getPackageNames().toArray(new String[0]));
        }
    }

public String[] selectImports(AnnotationMetadata annotationMetadata) {
    if (!this.isEnabled(annotationMetadata)) {
        return NO_IMPORTS;
    } else {
        AutoConfigurationImportSelector.AutoConfigurationEntry autoConfigurationEntry = this.getAutoConfigurationEntry(annotationMetadata);
        return StringUtils.toStringArray(autoConfigurationEntry.getConfigurations());
    }
}

protected AutoConfigurationImportSelector.AutoConfigurationEntry getAutoConfigurationEntry(AnnotationMetadata annotationMetadata) {
    if (!this.isEnabled(annotationMetadata)) {
        return EMPTY_ENTRY;
    } else {
        AnnotationAttributes attributes = this.getAttributes(annotationMetadata);
        //获取所有候选的配置 然后将配置过滤 去重，最后再封装
        List<String> configurations = this.getCandidateConfigurations(annotationMetadata, attributes);
        configurations = this.removeDuplicates(configurations);
        Set<String> exclusions = this.getExclusions(annotationMetadata, attributes);
        this.checkExcludedClasses(configurations, exclusions);
        configurations.removeAll(exclusions);
        configurations = this.getConfigurationClassFilter().filter(configurations);
        this.fireAutoConfigurationImportEvents(configurations, exclusions);
        return new AutoConfigurationImportSelector.AutoConfigurationEntry(configurations, exclusions);
    }
}

protected List<String> getCandidateConfigurations(AnnotationMetadata metadata, AnnotationAttributes attributes) {
    List<String> configurations = SpringFactoriesLoader.loadFactoryNames(this.getSpringFactoriesLoaderFactoryClass(), this.getBeanClassLoader());
    Assert.notEmpty(configurations, "No auto configuration classes found in META-INF/spring.factories. If you are using a custom packaging, make sure that file is correct.");
    return configurations;
}

public static List<String> loadFactoryNames(Class<?> factoryType, @Nullable ClassLoader classLoader) {
    ClassLoader classLoaderToUse = classLoader;
    if (classLoader == null) {
        classLoaderToUse = SpringFactoriesLoader.class.getClassLoader();
    }
    String factoryTypeName = factoryType.getName();
    return (List)loadSpringFactories(classLoaderToUse).getOrDefault(factoryTypeName, Collections.emptyList());
}

private static Map<String, List<String>> loadSpringFactories(ClassLoader classLoader) {
            Enumeration urls = classLoader.getResources("META-INF/spring.factories");
            }