标签：rop missing time context web get response springioc type
主类 @SpringBootApplication 开启了自动配置
@Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) @Documented @Inherited @SpringBootConfiguration @EnableAutoConfiguration//这里开启了自动配置 @ComponentScan(excludeFilters = { @Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class), @Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) }) public @interface SpringBootApplication { ... }
@Import(EnableAutoConfigurationImportSelector.class) 通过注解的方式实现把实例EnableAutoConfigurationImportSelector加入springIOC容器中，
EnableAutoConfigurationImportSelector实现了接口ImportSelector，并在其父类AutoConfigurationImportSelector中实现了ImportSelector定义的
org.springframework.context.annotation.ImportSelector#selectImports 【String[] selectImports(AnnotationMetadata importingClassMetadata)】)，
selectImports返回了一系列的***AutoConfiguration配置类,例如org.springframework.boot.autoconfigure.web.HttpEncodingAutoConfiguration，具体返回内容请查看动图一
@Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) @Documented @Inherited @AutoConfigurationPackage @Import(EnableAutoConfigurationImportSelector.class) public @interface EnableAutoConfiguration { ... }
org.springframework.boot.autoconfigure.web.HttpEncodingAutoConfiguration 中通过注解 @ConditionalXXX 定义了创建bean的条件 ，
例如下面代码片段的 @ConditionalOnMissingBean(CharacterEncodingFilter.class)定义了当CharacterEncodingFilter类型的bean不存在才创建bean，当我们通过maven引入某个starter后（例如 spring-boot-starter-web），会匹配@Conditional定义的条件从而创建bean
@Configuration @EnableConfigurationProperties(HttpEncodingProperties.class) @ConditionalOnWebApplication @ConditionalOnClass(CharacterEncodingFilter.class) @ConditionalOnProperty(prefix = "spring.http.encoding", value = "enabled", matchIfMissing = true) public class HttpEncodingAutoConfiguration { private final HttpEncodingProperties properties; public HttpEncodingAutoConfiguration(HttpEncodingProperties properties) { this.properties = properties; } @Bean @ConditionalOnMissingBean(CharacterEncodingFilter.class) public CharacterEncodingFilter characterEncodingFilter() { CharacterEncodingFilter filter = new OrderedCharacterEncodingFilter(); filter.setEncoding(this.properties.getCharset().name()); filter.setForceRequestEncoding(this.properties.shouldForce(Type.REQUEST)); filter.setForceResponseEncoding(this.properties.shouldForce(Type.RESPONSE)); return filter; } ... }
自动化配置类都有一个这样的注解@EnableConfigurationProperties ，例如 @EnableConfigurationProperties(HttpEncodingProperties.class) 来关联配置文件（application.yml或application.properties）的内容，可以打开这些类来看支持哪些配置项
标签：rop missing time context web get response springioc type
原文地址：https://www.cnblogs.com/LDDXFS/p/springboot.html
