SpringBoot-07-配置文件配置原理

4.11 配置文件配置原理

• springboot启动时，会自动配置spring-boot-autoconfigure-2.7.0.jar/META-NF/spring.factories核心文件中的xxxAutoConfiguration
• Configuration：配置类，会被spring接管配置
• spring.factories文件中自动配置类有上百项，如下：

org.springframework.boot.autoconfigure.admin.SpringApplicationAdminJmxAutoConfiguration
org.springframework.boot.autoconfigure.aop.AopAutoConfiguration
org.springframework.boot.autoconfigure.amqp.RabbitAutoConfiguration
org.springframework.boot.autoconfigure.batch.BatchAutoConfiguration
org.springframework.boot.autoconfigure.cache.CacheAutoConfiguration
org.springframework.boot.autoconfigure.cassandra.CassandraAutoConfiguration
org.springframework.boot.autoconfigure.context.ConfigurationPropertiesAutoConfiguration
org.springframework.boot.autoconfigure.context.LifecycleAutoConfiguration
org.springframework.boot.autoconfigure.context.MessageSourceAutoConfiguration
org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration
org.springframework.boot.autoconfigure.couchbase.CouchbaseAutoConfiguration
org.springframework.boot.autoconfigure.dao.PersistenceExceptionTranslationAutoConfiguration
org.springframework.boot.autoconfigure.data.cassandra.CassandraDataAutoConfiguration
org.springframework.boot.autoconfigure.data.cassandra.CassandraReactiveDataAutoConfiguration
org.springframework.boot.autoconfigure.data.cassandra.CassandraReactiveRepositoriesAutoConfiguration
org.springframework.boot.autoconfigure.data.cassandra.CassandraRepositoriesAutoConfiguration
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseDataAutoConfiguration
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseReactiveDataAutoConfiguration
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseReactiveRepositoriesAutoConfiguration
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseRepositoriesAutoConfiguration
org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchDataAutoConfiguration
org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchRepositoriesAutoConfiguration
org.springframework.boot.autoconfigure.data.elasticsearch.ReactiveElasticsearchRepositoriesAutoConfiguration
org.springframework.boot.autoconfigure.data.elasticsearch.ReactiveElasticsearchRestClientAutoConfiguration
org.springframework.boot.autoconfigure.data.jdbc.JdbcRepositoriesAutoConfiguration
org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration
org.springframework.boot.autoconfigure.data.ldap.LdapRepositoriesAutoConfiguration
org.springframework.boot.autoconfigure.data.mongo.MongoDataAutoConfiguration
org.springframework.boot.autoconfigure.data.mongo.MongoReactiveDataAutoConfiguration
org.springframework.boot.autoconfigure.data.mongo.MongoReactiveRepositoriesAutoConfiguration
org.springframework.boot.autoconfigure.data.mongo.MongoRepositoriesAutoConfiguration
org.springframework.boot.autoconfigure.data.neo4j.Neo4jDataAutoConfiguration
org.springframework.boot.autoconfigure.data.neo4j.Neo4jReactiveDataAutoConfiguration
org.springframework.boot.autoconfigure.data.neo4j.Neo4jReactiveRepositoriesAutoConfiguration
org.springframework.boot.autoconfigure.data.neo4j.Neo4jRepositoriesAutoConfiguration
org.springframework.boot.autoconfigure.data.r2dbc.R2dbcDataAutoConfiguration
org.springframework.boot.autoconfigure.data.r2dbc.R2dbcRepositoriesAutoConfiguration
org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration
org.springframework.boot.autoconfigure.data.redis.RedisReactiveAutoConfiguration
org.springframework.boot.autoconfigure.data.redis.RedisRepositoriesAutoConfiguration
org.springframework.boot.autoconfigure.data.rest.RepositoryRestMvcAutoConfiguration
org.springframework.boot.autoconfigure.data.web.SpringDataWebAutoConfiguration
org.springframework.boot.autoconfigure.elasticsearch.ElasticsearchRestClientAutoConfiguration
org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration
org.springframework.boot.autoconfigure.freemarker.FreeMarkerAutoConfiguration
org.springframework.boot.autoconfigure.graphql.GraphQlAutoConfiguration
org.springframework.boot.autoconfigure.graphql.data.GraphQlReactiveQueryByExampleAutoConfiguration
org.springframework.boot.autoconfigure.graphql.data.GraphQlReactiveQuerydslAutoConfiguration
org.springframework.boot.autoconfigure.graphql.data.GraphQlQueryByExampleAutoConfiguration
org.springframework.boot.autoconfigure.graphql.data.GraphQlQuerydslAutoConfiguration
org.springframework.boot.autoconfigure.graphql.reactive.GraphQlWebFluxAutoConfiguration
org.springframework.boot.autoconfigure.graphql.rsocket.GraphQlRSocketAutoConfiguration
org.springframework.boot.autoconfigure.graphql.rsocket.RSocketGraphQlClientAutoConfiguration
org.springframework.boot.autoconfigure.graphql.security.GraphQlWebFluxSecurityAutoConfiguration
org.springframework.boot.autoconfigure.graphql.security.GraphQlWebMvcSecurityAutoConfiguration
org.springframework.boot.autoconfigure.graphql.servlet.GraphQlWebMvcAutoConfiguration
org.springframework.boot.autoconfigure.groovy.template.GroovyTemplateAutoConfiguration
org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration
org.springframework.boot.autoconfigure.h2.H2ConsoleAutoConfiguration
org.springframework.boot.autoconfigure.hateoas.HypermediaAutoConfiguration
org.springframework.boot.autoconfigure.hazelcast.HazelcastAutoConfiguration
org.springframework.boot.autoconfigure.hazelcast.HazelcastJpaDependencyAutoConfiguration
org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration
org.springframework.boot.autoconfigure.http.codec.CodecsAutoConfiguration
org.springframework.boot.autoconfigure.influx.InfluxDbAutoConfiguration
org.springframework.boot.autoconfigure.info.ProjectInfoAutoConfiguration
org.springframework.boot.autoconfigure.integration.IntegrationAutoConfiguration
org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration
org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration
org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration
org.springframework.boot.autoconfigure.jdbc.JndiDataSourceAutoConfiguration
org.springframework.boot.autoconfigure.jdbc.XADataSourceAutoConfiguration
org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration
org.springframework.boot.autoconfigure.jms.JmsAutoConfiguration
org.springframework.boot.autoconfigure.jmx.JmxAutoConfiguration
org.springframework.boot.autoconfigure.jms.JndiConnectionFactoryAutoConfiguration
org.springframework.boot.autoconfigure.jms.activemq.ActiveMQAutoConfiguration
org.springframework.boot.autoconfigure.jms.artemis.ArtemisAutoConfiguration
org.springframework.boot.autoconfigure.jersey.JerseyAutoConfiguration
org.springframework.boot.autoconfigure.jooq.JooqAutoConfiguration
org.springframework.boot.autoconfigure.jsonb.JsonbAutoConfiguration
org.springframework.boot.autoconfigure.kafka.KafkaAutoConfiguration
org.springframework.boot.autoconfigure.availability.ApplicationAvailabilityAutoConfiguration
org.springframework.boot.autoconfigure.ldap.embedded.EmbeddedLdapAutoConfiguration
org.springframework.boot.autoconfigure.ldap.LdapAutoConfiguration
org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration
org.springframework.boot.autoconfigure.mail.MailSenderAutoConfiguration
org.springframework.boot.autoconfigure.mail.MailSenderValidatorAutoConfiguration
org.springframework.boot.autoconfigure.mongo.embedded.EmbeddedMongoAutoConfiguration
org.springframework.boot.autoconfigure.mongo.MongoAutoConfiguration
org.springframework.boot.autoconfigure.mongo.MongoReactiveAutoConfiguration
org.springframework.boot.autoconfigure.mustache.MustacheAutoConfiguration
org.springframework.boot.autoconfigure.neo4j.Neo4jAutoConfiguration
org.springframework.boot.autoconfigure.netty.NettyAutoConfiguration
org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration
org.springframework.boot.autoconfigure.quartz.QuartzAutoConfiguration
org.springframework.boot.autoconfigure.r2dbc.R2dbcAutoConfiguration
org.springframework.boot.autoconfigure.r2dbc.R2dbcTransactionManagerAutoConfiguration
org.springframework.boot.autoconfigure.rsocket.RSocketMessagingAutoConfiguration
org.springframework.boot.autoconfigure.rsocket.RSocketRequesterAutoConfiguration
org.springframework.boot.autoconfigure.rsocket.RSocketServerAutoConfiguration
org.springframework.boot.autoconfigure.rsocket.RSocketStrategiesAutoConfiguration
org.springframework.boot.autoconfigure.security.servlet.SecurityAutoConfiguration
org.springframework.boot.autoconfigure.security.servlet.UserDetailsServiceAutoConfiguration
org.springframework.boot.autoconfigure.security.servlet.SecurityFilterAutoConfiguration
org.springframework.boot.autoconfigure.security.reactive.ReactiveSecurityAutoConfiguration
org.springframework.boot.autoconfigure.security.reactive.ReactiveUserDetailsServiceAutoConfiguration
org.springframework.boot.autoconfigure.security.rsocket.RSocketSecurityAutoConfiguration
org.springframework.boot.autoconfigure.security.saml2.Saml2RelyingPartyAutoConfiguration
org.springframework.boot.autoconfigure.sendgrid.SendGridAutoConfiguration
org.springframework.boot.autoconfigure.session.SessionAutoConfiguration
org.springframework.boot.autoconfigure.security.oauth2.client.servlet.OAuth2ClientAutoConfiguration
org.springframework.boot.autoconfigure.security.oauth2.client.reactive.ReactiveOAuth2ClientAutoConfiguration
org.springframework.boot.autoconfigure.security.oauth2.resource.servlet.OAuth2ResourceServerAutoConfiguration
org.springframework.boot.autoconfigure.security.oauth2.resource.reactive.ReactiveOAuth2ResourceServerAutoConfiguration
org.springframework.boot.autoconfigure.solr.SolrAutoConfiguration
org.springframework.boot.autoconfigure.sql.init.SqlInitializationAutoConfiguration
org.springframework.boot.autoconfigure.task.TaskExecutionAutoConfiguration
org.springframework.boot.autoconfigure.task.TaskSchedulingAutoConfiguration
org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration
org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration
org.springframework.boot.autoconfigure.transaction.jta.JtaAutoConfiguration
org.springframework.boot.autoconfigure.validation.ValidationAutoConfiguration
org.springframework.boot.autoconfigure.web.client.RestTemplateAutoConfiguration
org.springframework.boot.autoconfigure.web.embedded.EmbeddedWebServerFactoryCustomizerAutoConfiguration
org.springframework.boot.autoconfigure.web.reactive.HttpHandlerAutoConfiguration
org.springframework.boot.autoconfigure.web.reactive.ReactiveMultipartAutoConfiguration
org.springframework.boot.autoconfigure.web.reactive.ReactiveWebServerFactoryAutoConfiguration
org.springframework.boot.autoconfigure.web.reactive.WebFluxAutoConfiguration
org.springframework.boot.autoconfigure.web.reactive.WebSessionIdResolverAutoConfiguration
org.springframework.boot.autoconfigure.web.reactive.error.ErrorWebFluxAutoConfiguration
org.springframework.boot.autoconfigure.web.reactive.function.client.ClientHttpConnectorAutoConfiguration
org.springframework.boot.autoconfigure.web.reactive.function.client.WebClientAutoConfiguration
org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration
org.springframework.boot.autoconfigure.web.servlet.ServletWebServerFactoryAutoConfiguration
org.springframework.boot.autoconfigure.web.servlet.error.ErrorMvcAutoConfiguration
org.springframework.boot.autoconfigure.web.servlet.HttpEncodingAutoConfiguration
org.springframework.boot.autoconfigure.web.servlet.MultipartAutoConfiguration
org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration
org.springframework.boot.autoconfigure.websocket.reactive.WebSocketReactiveAutoConfiguration
org.springframework.boot.autoconfigure.websocket.servlet.WebSocketServletAutoConfiguration
org.springframework.boot.autoconfigure.websocket.servlet.WebSocketMessagingAutoConfiguration
org.springframework.boot.autoconfigure.webservices.WebServicesAutoConfiguration
org.springframework.boot.autoconfigure.webservices.client.WebServiceTemplateAutoConfiguration

• 这配置文件中能配置的内容，都存在一个固有的规律xxxAutoConfiguration:自动配置类自动装配了默认属性—默认值xxxProperties，而xxxProperties又和配置文件绑定，我们就可以使用自定义的配置了！

• 所以我们可以在配置文件输入需要配置的属性，点开这个属性对应的xxxProperties属性类，里面的实例变量就是我们可以配置的内容。

• 每一个这样的xxxAutoConfiguration类都是容器中的一个组件，最后都加入到容器中；用他们来做自动配置；

• 每一个自动配置类可以进行自动配置功能；：

• 我们以HttpEncodingAutoConfiguration(Http编码自动配置)为例解释自动配置原理；

package org.springframework.boot.autoconfigure.web.servlet;

import org.springframework.boot.autoconfigure.AutoConfiguration;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
import org.springframework.boot.autoconfigure.web.ServerProperties;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.boot.web.server.WebServerFactoryCustomizer;
import org.springframework.boot.web.servlet.filter.OrderedCharacterEncodingFilter;
import org.springframework.boot.web.servlet.server.ConfigurableServletWebServerFactory;
import org.springframework.boot.web.servlet.server.Encoding;
import org.springframework.context.annotation.Bean;
import org.springframework.core.Ordered;
import org.springframework.web.filter.CharacterEncodingFilter;

/**
 * {@link EnableAutoConfiguration Auto-configuration} for configuring the encoding to use
 * in web applications.
 *
 * @author Stephane Nicoll
 * @author Brian Clozel
 * @since 2.0.0
 */
@AutoConfiguration
/*表示这是一个自动配置类，跟在springmvc编写的配置文件一样，也可以给容器中添加组件
启动指定类的ConfigurationProperties功能：
进入这个HttpProperties查看，将配置文件中对应的值和ServerProperties绑定起来；
并把ServerProperties加入到ioc容器中
*/
@EnableConfigurationProperties(ServerProperties.class)

//Spring底层@Conditional注解
//根据不同的条件判断，如果满足指定的条件，整个配置类里面的配置就会生效：
//这里的意思就是判断当前应用是否是web应用，如果是，当前配置类生效
@ConditionalOnWebApplication(type = ConditionalOnWebApplication.Type.SERVLET)

//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：
@ConditionalOnClass(CharacterEncodingFilter.class)

//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spring.http.encoding.enabled=true,也是默认生效的；
@ConditionalOnProperty(prefix = "server.servlet.encoding", value = "enabled", matchIfMissing = true)
public class HttpEncodingAutoConfiguration {
   //已经和SpringBoot的配置文件映射了
   private final Encoding 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(ServerProperties properties) {
      this.properties = properties.getServlet().getEncoding();
   }
   //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
   @Bean
   @ConditionalOnMissingBean//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(Encoding.Type.REQUEST));
      filter.setForceResponseEncoding(this.properties.shouldForce(Encoding.Type.RESPONSE));
      return filter;
   }

   @Bean
   public LocaleCharsetMappingsCustomizer localeCharsetMappingsCustomizer() {
      return new LocaleCharsetMappingsCustomizer(this.properties);
   }

   static class LocaleCharsetMappingsCustomizer
         implements WebServerFactoryCustomizer<ConfigurableServletWebServerFactory>, Ordered {

      private final Encoding properties;

      LocaleCharsetMappingsCustomizer(Encoding properties) {
         this.properties = properties;
      }

      @Override
      public void customize(ConfigurableServletWebServerFactory factory) {
         if (this.properties.getMapping() != null) {
            factory.setLocaleCharsetMappings(this.properties.getMapping());
         }
      }

      @Override
      public int getOrder() {
         return 0;
      }

   }

}

• 一句话总结：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；

• 所有在配置文件中能配置的属性都是在XxxProperties类中封装着；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

• 这就是自动装配的原理！

  • 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在SpringBoot默认写好的自动配置类当中；
  • 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存在在其中，我们就不需要再手动配置了)
  • 4)、给容器中自动配置类添加组件的时候，会从xxxproperties类中获取某些属性。我们只需要在配置文件中指定这些属性的值即可；
  • xxxAutoConfigurartion: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；

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