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https://www.toutiao.com/c/user/54449368910/#mid=1591720133858307
3)、每一个自动配置类进行自动配置功能;
一但这个配置类生效;这个配置类就会给容器中添加各种组件;这些组件的属性是从对应的properties类中获取
的,这些类里面的每一个属性又是和配置文件绑定的;
5)、所有在配置文件中能配置的属性都是在xxxxProperties类中封装者‘;配置文件能配置什么就可以参照某个功
1)、SpringBoot启动会加载大量的自动配置类
2)、我们看我们需要的功能有没有SpringBoot默认写好的自动配置类;
3)、我们再来看这个自动配置类中到底配置了哪些组件;(只要我们要用的组件有,我们就不需要再来配置了)
4)、给容器中自动配置类添加组件的时候,会从properties类中获取某些属性。我们就可以在配置文件中指定这
自动配置原理
配置文件到底能写什么?怎么写?自动配置原理;
1、自动配置原理:
1)、SpringBoot启动的时候加载主配置类,开启了自动配置功能 @EnableAutoConfiguration
2)、@EnableAutoConfiguration 作用:
- 利用EnableAutoConfigurationImportSelector给容器中导入一些组件?
- 可以查看selectImports()方法的内容;
- List configurations = getCandidateConfigurations(annotationMetadata, attributes);获取候选的配置
SpringFactoriesLoader.loadFactoryNames()扫描所有jar包类路径下 META‐INF/spring.factories
把扫描到的这些文件的内容包装成properties对象,从properties中获取到EnableAutoConfiguration.class类(类名)对应的值,然后把他们添加在容器中
将 类路径下 META-INF/spring.factories 里面配置的所有EnableAutoConfiguration的值加入到了容器中;
# AutoConfigureCache auto-configuration imports org.springframework.boot.test.autoconfigure.core.AutoConfigureCache=\ org.springframework.boot.autoconfigure.cache.CacheAutoConfiguration # AutoConfigureDataJpa auto-configuration imports org.springframework.boot.test.autoconfigure.orm.jpa.AutoConfigureDataJpa=\ org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration,\ org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration,\ org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration,\ org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration,\ org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration,\ org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration,\ org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration,\ org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration # AutoConfigureDataMongo auto-configuration imports org.springframework.boot.test.autoconfigure.data.mongo.AutoConfigureDataMongo=\ org.springframework.boot.autoconfigure.data.mongo.MongoDataAutoConfiguration,\ org.springframework.boot.autoconfigure.data.mongo.MongoRepositoriesAutoConfiguration,\ org.springframework.boot.autoconfigure.mongo.MongoAutoConfiguration,\ org.springframework.boot.autoconfigure.mongo.embedded.EmbeddedMongoAutoConfiguration # AutoConfigureJdbc auto-configuration imports org.springframework.boot.test.autoconfigure.jdbc.AutoConfigureJdbc=\ org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration,\ org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration,\ org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration,\ org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration,\ org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration,\ org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration # AutoConfigureTestDatabase auto-configuration imports org.springframework.boot.test.autoconfigure.jdbc.AutoConfigureTestDatabase=\ org.springframework.boot.test.autoconfigure.jdbc.TestDatabaseAutoConfiguration,\ org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration # AutoConfigureJson auto-configuration imports org.springframework.boot.test.autoconfigure.json.AutoConfigureJson=\ org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration,\ org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration # AutoConfigureJsonTesters auto-configuration imports org.springframework.boot.test.autoconfigure.json.AutoConfigureJsonTesters=\ org.springframework.boot.test.autoconfigure.json.JsonTestersAutoConfiguration,\ org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration,\ org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration # AutoConfigureMockMvc auto-configuration imports org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc=\ org.springframework.boot.test.autoconfigure.web.servlet.MockMvcAutoConfiguration,\ org.springframework.boot.test.autoconfigure.web.servlet.MockMvcSecurityAutoConfiguration,\ org.springframework.boot.test.autoconfigure.web.servlet.MockMvcWebClientAutoConfiguration,\ org.springframework.boot.test.autoconfigure.web.servlet.MockMvcWebDriverAutoConfiguration # AutoConfigureMockRestServiceServer org.springframework.boot.test.autoconfigure.web.client.AutoConfigureMockRestServiceServer=\ org.springframework.boot.test.autoconfigure.web.client.MockRestServiceServerAutoConfiguration # AutoConfigureRestDocs auto-configuration imports org.springframework.boot.test.autoconfigure.restdocs.AutoConfigureRestDocs=\ org.springframework.boot.test.autoconfigure.restdocs.RestDocsAutoConfiguration # AutoConfigureTestDatabase auto-configuration imports org.springframework.boot.test.autoconfigure.orm.jpa.AutoConfigureTestDatabase=\ org.springframework.boot.test.autoconfigure.jdbc.TestDatabaseAutoConfiguration,\ org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration # AutoConfigureTestEntityManager auto-configuration imports org.springframework.boot.test.autoconfigure.orm.jpa.AutoConfigureTestEntityManager=\ org.springframework.boot.test.autoconfigure.orm.jpa.TestEntityManagerAutoConfiguration # AutoConfigureWebClient auto-configuration imports org.springframework.boot.test.autoconfigure.web.client.AutoConfigureWebClient=\ org.springframework.boot.test.autoconfigure.web.client.WebClientRestTemplateAutoConfiguration,\ org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration,\ org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration,\ org.springframework.boot.autoconfigure.web.HttpMessageConvertersAutoConfiguration,\ org.springframework.boot.autoconfigure.web.WebClientAutoConfiguration # AutoConfigureWebMvc auto-configuration imports org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureWebMvc=\ org.springframework.boot.autoconfigure.context.MessageSourceAutoConfiguration,\ org.springframework.boot.autoconfigure.freemarker.FreeMarkerAutoConfiguration,\ org.springframework.boot.autoconfigure.groovy.template.GroovyTemplateAutoConfiguration,\ org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration,\ org.springframework.boot.autoconfigure.hateoas.HypermediaAutoConfiguration,\ org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration,\ org.springframework.boot.autoconfigure.mustache.MustacheAutoConfiguration,\ org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration,\ org.springframework.boot.autoconfigure.validation.ValidationAutoConfiguration,\ org.springframework.boot.autoconfigure.web.ErrorMvcAutoConfiguration,\ org.springframework.boot.autoconfigure.web.HttpMessageConvertersAutoConfiguration,\ org.springframework.boot.autoconfigure.web.ServerPropertiesAutoConfiguration,\ org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration # DefaultTestExecutionListenersPostProcessors org.springframework.boot.test.context.DefaultTestExecutionListenersPostProcessor=\ org.springframework.boot.test.autoconfigure.SpringBootDependencyInjectionTestExecutionListener$PostProcessor # Spring Test ContextCustomizerFactories org.springframework.test.context.ContextCustomizerFactory=\ org.springframework.boot.test.autoconfigure.OverrideAutoConfigurationContextCustomizerFactory,\ org.springframework.boot.test.autoconfigure.filter.TypeExcludeFiltersContextCustomizerFactory,\ org.springframework.boot.test.autoconfigure.properties.PropertyMappingContextCustomizerFactory,\ org.springframework.boot.test.autoconfigure.web.servlet.WebDriverContextCustomizerFactory # Test Execution Listeners org.springframework.test.context.TestExecutionListener=\ org.springframework.boot.test.autoconfigure.restdocs.RestDocsTestExecutionListener,\ org.springframework.boot.test.autoconfigure.web.client.MockRestServiceServerResetTestExecutionListener,\ org.springframework.boot.test.autoconfigure.web.servlet.MockMvcPrintOnlyOnFailureTestExecutionListener,\ org.springframework.boot.test.autoconfigure.web.servlet.WebDriverTestExecutionListener每一个这样的 xxxAutoConfiguration类都是容器中的一个组件,都加入到容器中;用他们来做自动配置;
3)、每一个自动配置类进行自动配置功能;
4)、以HttpEncodingAutoConfiguration(Http编码自动配置)为例解释自动配置原理;
@Configuration //表示这是一个配置类,以前编写的配置文件一样,也可以给容器中添加组件 @EnableConfigurationProperties(HttpEncodingProperties.class) //启动指定类的 ConfigurationProperties功能;将配置文件中对应的值和HttpEncodingProperties绑定起来;并把 HttpEncodingProperties加入到ioc容器中 @ConditionalOnWebApplication //Spring底层@Conditional注解(Spring注解版),根据不同的条件,如果 满足指定的条件,整个配置类里面的配置就会生效; 判断当前应用是否是web应用,如果是,当前配置类生效 @ConditionalOnClass(CharacterEncodingFilter.class) //判断当前项目有没有这个类 CharacterEncodingFilter;SpringMVC中进行乱码解决的过滤器; @ConditionalOnProperty(prefix = "spring.http.encoding", value = "enabled", matchIfMissing = true) //判断配置文件中是否存在某个配置 spring.http.encoding.enabled;如果不存在,判断也是成立的 //即使我们配置文件中不配置pring.http.encoding.enabled=true,也是默认生效的; public class HttpEncodingAutoConfiguration { //他已经和SpringBoot的配置文件映射了 private final HttpEncodingProperties properties;
//只有一个有参构造器的情况下,参数的值就会从容器中拿 public HttpEncodingAutoConfiguration(HttpEncodingProperties properties) { this.properties = properties; } @Bean //给容器中添加一个组件,这个组件的某些值需要从properties中获取 @ConditionalOnMissingBean(CharacterEncodingFilter.class) //判断容器没有这个组件? 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; }根据当前不同的条件判断,决定这个配置类是否生效?
一但这个配置类生效;这个配置类就会给容器中添加各种组件;这些组件的属性是从对应的properties类中获取
的,这些类里面的每一个属性又是和配置文件绑定的;
5)、所有在配置文件中能配置的属性都是在xxxxProperties类中封装者‘;配置文件能配置什么就可以参照某个功
能对应的这个属性类
@ConfigurationProperties(prefix = "spring.http.encoding") //从配置文件中获取指定的值和bean的属 性进行绑定 public class HttpEncodingProperties { public static final Charset DEFAULT_CHARSET = Charset.forName("UTF‐8");精髓:
1)、SpringBoot启动会加载大量的自动配置类
2)、我们看我们需要的功能有没有SpringBoot默认写好的自动配置类;
3)、我们再来看这个自动配置类中到底配置了哪些组件;(只要我们要用的组件有,我们就不需要再来配置了)
4)、给容器中自动配置类添加组件的时候,会从properties类中获取某些属性。我们就可以在配置文件中指定这
些属性的值;
xxxxAutoConfigurartion:自动配置类;给容器中添加组件
xxxxProperties:封装配置文件中相关属性;
@Conditional扩展
作用:必须是@Conditional指定的条件成立,才给容器中添加组件,配置配里面的所有内容才生效;
自动配置类必须在一定的条件下才能生效;
我们怎么知道哪些自动配置类生效;
我们可以通过启用 debug=true属性;来让控制台打印自动配置报告,这样我们就可以很方便的知道哪些自动配置
类生效;
#开启SpringBoot的debug模式 debug=true
========================= AUTO‐CONFIGURATION REPORT ========================= Positive matches:(自动配置类启用的) ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ DispatcherServletAutoConfiguration matched: ‐ @ConditionalOnClass found required class 'org.springframework.web.servlet.DispatcherServlet'; @ConditionalOnMissingClass did not find unwanted class (OnClassCondition) ‐ @ConditionalOnWebApplication (required) found StandardServletEnvironment (OnWebApplicationCondition) Negative matches:(没有启动,没有匹配成功的自动配置类) ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ ActiveMQAutoConfiguration: Did not match: ‐ @ConditionalOnClass did not find required classes 'javax.jms.ConnectionFactory', 'org.apache.activemq.ActiveMQConnectionFactory' (OnClassCondition) AopAutoConfiguration: Did not match: ‐ @ConditionalOnClass did not find required classes 'org.aspectj.lang.annotation.Aspect', 'org.aspectj.lang.reflect.Advice' (OnClassConditio