<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd">
  <bean id="beanE" class="com.study.spring.sample.config.BeanE" />
  <bean id="beanF" class="com.study.spring.sample.config.BeanF" ></bean>
  <context:annotation-config/>
  <context:component-scan base-package="com.study.spring.sample.config" ></context:component-scan>
</beans>
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public class XMLConfigMain {
  public static void main(String[] args) {
    ApplicationContext context = new GenericXmlApplicationContext(
        "classpath:com/study/spring/sample/config/application.xml");
    BeanF bf = context.getBean(BeanF.class);
    bf.do1();
  }
}
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@Configuration
@ComponentScan("com.study.spring.sample.config")
public class JavaBasedMain {
  @Bean
  public BeanH getBeanH() {
    return new BeanH();
  }
  public static void main(String[] args) {
    ApplicationContext context = new AnnotationConfigApplicationContext(JavaBasedMain.class);
    BeanH bh = context.getBean(BeanH.class);
    bh.doH();
  }
}
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public class AnnotationMain {
  public static void main(String[] args) {
    ApplicationContext context = new AnnotationConfigApplicationContext("com.study.spring.sample.config");
    BeanG bg = context.getBean(BeanG.class);
    bg.dog();
  }
}
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public AnnotationConfigApplicationContext() {
    this.reader = new AnnotatedBeanDefinitionReader(this);
    this.scanner = new ClassPathBeanDefinitionScanner(this);
  }
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public interface BeanMetadataElement {
  /**
   * Return the configuration source {@code Object} for this metadata element
   * (may be {@code null}).
   */
  @Nullable
  default Object getSource() {
    return null;
  }
}
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public class BeanMetadataAttribute implements BeanMetadataElement {
  private final String name;
  @Nullable
  private final Object value;
  @Nullable
  private Object source;
}
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public interface AttributeAccessor {
  /**
   * Set the attribute defined by {@code name} to the supplied {@code value}.
   * If {@code value} is {@code null}, the attribute is {@link #removeAttribute removed}.
   * <p>In general, users should take care to prevent overlaps with other
   * metadata attributes by using fully-qualified names, perhaps using
   * class or package names as prefix.
   * @param name the unique attribute key
   * @param value the attribute value to be attached
   */
  void setAttribute(String name, @Nullable Object value);
  /**
   * Get the value of the attribute identified by {@code name}.
   * Return {@code null} if the attribute doesn't exist.
   * @param name the unique attribute key
   * @return the current value of the attribute, if any
   */
  @Nullable
  Object getAttribute(String name);
  /**
   * Remove the attribute identified by {@code name} and return its value.
   * Return {@code null} if no attribute under {@code name} is found.
   * @param name the unique attribute key
   * @return the last value of the attribute, if any
   */
  @Nullable
  Object removeAttribute(String name);
  /**
   * Return {@code true} if the attribute identified by {@code name} exists.
   * Otherwise return {@code false}.
   * @param name the unique attribute key
   */
  boolean hasAttribute(String name);
  /**
   * Return the names of all attributes.
   */
  String[] attributeNames();
}
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public abstract class AttributeAccessorSupport implements AttributeAccessor, Serializable {
  /** Map with String keys and Object values. */
  private final Map<String, Object> attributes = new LinkedHashMap<>();
  @Override
  public void setAttribute(String name, @Nullable Object value) {
    Assert.notNull(name, "Name must not be null");
    if (value != null) {
      this.attributes.put(name, value);
    }
    else {
      removeAttribute(name);
    }
  }
    //  ......
}
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public interface AnnotatedBeanDefinition extends BeanDefinition {
  /**
   * Obtain the annotation metadata (as well as basic class metadata)
   * for this bean definition's bean class.
   * @return the annotation metadata object (never {@code null})
   */
  AnnotationMetadata getMetadata();
  /**
   * Obtain metadata for this bean definition's factory method, if any.
   * @return the factory method metadata, or {@code null} if none
   * @since 4.1.1
   */
  @Nullable
  MethodMetadata getFactoryMethodMetadata();
}
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