一. 自动配置的魔法
Spring Boot auto-configuration magic comes from spring-boot-autoconfigure-{version}.jar
自动装配的魔法来自 spring-boot-autoconfigure-(version).jar
spring.factories 文件包括了 需要的所有spring -boot - autoconfigure-{version}.jar
二.与自动配置有关的一些注解
@ConditionalOnClass({Servlet.class ,DispatherServlet.class ,WebMvcConfigurerAdapter.class})
英文 :This auto-configuration is enabled if any of the mentioned class are in the classpath.
中文: 这个自动配置生效条件是如果被提到的类在classpath中.
@ConditionalOnMissingBean(WebMvcConfigurationSuppot.class):
英文:This auto-configurationis enabled only if application does not explicity delare a bean of the WebMvcConfigurationSuppot.class
中文:这个自动配置生效条件是如果没有显示声明WebMvcConfigurationSuppot bean
@AutoconfigureOrder(Ordered.HIGHEST_PRECEDENCE+10)
英文: This specifies the precedence of this specific auto-configuration
中文 :这个指明了自动配置类的优先级.
举例 :来看下面代码片段
@ConditionalOnBean(ViewResolver.class) :
注解含义: 如果在classpath 中有 viewRresolver 这个类. 则创建 一个 bean ContentNegotiatingViewResolver
@ConditionalOnMissingBean(name = "viewResolver", value=ContentNegotiationgViewResolver.class):
注解含义:
英文 :Create this bean if there are no explicity delcared beans of the name viewResolver and of type ContentNegotiatingViewResolver.class
中文: 如果没有显示声明 名字是 viewResolver 和 类型是 ContentNegotiatingViewResolver,则创建这个bean
总结: summarize
To summarize ,all the auto-configuration logic is executed at the start of a Spring Boot application . if a specific class(from a specific dependency or starter project) is available on the classpath , then the autoconfiguration classes are executed .This auto-configurationclasses look at what beans are already configured . Based on the existing beans ,they enable the creation of the default beans .
总结, 所有自动装配的逻辑在 spring boot application 应用开始时执行的. 如果一个指定的类在 classpath中有效, 这些自动装配的类被执行. 自动装配的类查看这些已经配置的哪些bean. 基于这些beans ,它们能创造默认的bean.
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