• @Scope 原始碼

@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Scope {

	/**
	 * Alias for {@link #scopeName}.
	 * @see #scopeName
	 */
	@AliasFor("scopeName")
	String value() default "";

	/**
	 * Specifies the name of the scope to use for the annotated component/bean.
	 * <p>Defaults to an empty string ({@code ""}) which implies
	 * {@link ConfigurableBeanFactory#SCOPE_SINGLETON SCOPE_SINGLETON}.
	 * @since 4.2
	 * @see ConfigurableBeanFactory#SCOPE_PROTOTYPE
	 * @see ConfigurableBeanFactory#SCOPE_SINGLETON
	 * @see org.springframework.web.context.WebApplicationContext#SCOPE_REQUEST
	 * @see org.springframework.web.context.WebApplicationContext#SCOPE_SESSION
	 * @see #value
	 */
	@AliasFor("value")
	String scopeName() default "";

	/**
	 * Specifies whether a component should be configured as a scoped proxy
	 * and if so, whether the proxy should be interface-based or subclass-based.
	 * <p>Defaults to {@link ScopedProxyMode#DEFAULT}, which typically indicates
	 * that no scoped proxy should be created unless a different default
	 * has been configured at the component-scan instruction level.
	 * <p>Analogous to {@code <aop:scoped-proxy/>} support in Spring XML.
	 * @see ScopedProxyMode
	 */
	ScopedProxyMode proxyMode() default ScopedProxyMode.DEFAULT;
}
 

• Bean 的作用域有四個：

singleton：單例項，每次都獲取同一個例項，例項的是 IOC 初始化後建立，IOC 容器負責銷燬，
prototype：多例項，每次獲取不同的例項，例項是在呼叫的建立，IOC 容器只負責建立，不負責銷燬，
request：同一次請求域中有效，在 web 環境有效，
session：同一次session中有效，在 web 環境有效，

• @Lazy 懶載入

針對的是單例項，IOC 容器初始化完成後不載入例項，在第一次獲取例項時載入，以後獲取都是同一個例項