《开启微服务之旅：Spring Boot 从入门到实践》（三）

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

# Auto Configure

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\

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.cloud.CloudAutoConfiguration,\

org.springframework.boot.autoconfigure.context.ConfigurationPropertiesAutoConfiguration,\

org.springframework.boot.autoconfigure.context.MessageSourceAutoConfiguration,\

org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration,\

org.springframework.boot.autoconfigure.couchbase.CouchbaseAutoConfiguration,\

org.springframework.boot.autoconfigure.dao.PersistenceExceptionTranslationAutoConfiguration,

\ o

rg.springframework.boot.autoconfigure.data.cassandra.CassandraDataAutoConfiguration,\

org.springframework.boot.autoconfigure.data.cassandra.CassandraRepositoriesAutoConfiguration

,\

org.springframework.boot.autoconfigure.data.couchbase.CouchbaseDataAutoConfiguration,\

org.springframework.boot.autoconfigure.data.couchbase.CouchbaseRepositoriesAutoConfiguration

,\

org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchAutoConfiguration,\

org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchDataAutoConfiguration

,\

org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchRepositoriesAutoConfi

guration,\

org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration,\

org.springframework.boot.autoconfigure.data.ldap.LdapDataAutoConfiguration,\

org.springframework.boot.autoconfigure.data.ldap.LdapRepositoriesAutoConfiguration,\

org.springframework.boot.autoconfigure.data.mongo.MongoDataAutoConfiguration,\

org.springframework.boot.autoconfigure.data.mongo.MongoRepositoriesAutoConfiguration,\

org.springframework.boot.autoconfigure.data.neo4j.Neo4jDataAutoConfiguration,\

org.springframework.boot.autoconfigure.data.neo4j.Neo4jRepositoriesAutoConfiguration,\

org.springframework.boot.autoconfigure.data.solr.SolrRepositoriesAutoConfiguration,\

org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration,\

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.jest.JestAutoConfiguration,\

org.springframework.boot.autoconfigure.freemarker.FreeMarkerAutoConfiguration,\

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.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.flyway.FlywayAutoConfiguration,\

org.springframework.boot.autoconfigure.groovy.template.GroovyTemplateAutoConfiguration,\

org.springframework.boot.autoconfigure.jersey.JerseyAutoConfiguration,\

org.springframework.boot.autoconfigure.jooq.JooqAutoConfiguration,\

org.springframework.boot.autoconfigure.kafka.KafkaAutoConfiguration,\

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.mobile.DeviceResolverAutoConfiguration,\

org.springframework.boot.autoconfigure.mobile.DeviceDelegatingViewResolverAutoConfiguration,

\ o

rg.springframework.boot.autoconfigure.mobile.SitePreferenceAutoConfiguration,\

org.springframework.boot.autoconfigure.mongo.embedded.EmbeddedMongoAutoConfiguration,\

org.springframework.boot.autoconfigure.mongo.MongoAutoConfiguration,\

org.springframework.boot.autoconfigure.mustache.MustacheAutoConfiguration,\

org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration,\

org.springframework.boot.autoconfigure.reactor.ReactorAutoConfiguration,\

org.springframework.boot.autoconfigure.security.SecurityAutoConfiguration,\

org.springframework.boot.autoconfigure.security.SecurityFilterAutoConfiguration,\

org.springframework.boot.autoconfigure.security.FallbackWebSecurityAutoConfiguration,\

org.springframework.boot.autoconfigure.security.oauth2.OAuth2AutoConfiguration,\

org.springframework.boot.autoconfigure.sendgrid.SendGridAutoConfiguration,\

org.springframework.boot.autoconfigure.session.SessionAutoConfiguration,\

org.springframework.boot.autoconfigure.social.SocialWebAutoConfiguration,\

org.springframework.boot.autoconfigure.social.FacebookAutoConfiguration,\

org.springframework.boot.autoconfigure.social.LinkedInAutoConfiguration,\

org.springframework.boot.autoconfigure.social.TwitterAutoConfiguration,\

org.springframework.boot.autoconfigure.solr.SolrAutoConfiguration,\

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.DispatcherServletAutoConfiguration,\

org.springframework.boot.autoconfigure.web.EmbeddedServletContainerAutoConfiguration,\

org.springframework.boot.autoconfigure.web.ErrorMvcAutoConfiguration,\

org.springframework.boot.autoconfigure.web.HttpEncodingAutoConfiguration,\

org.springframework.boot.autoconfigure.web.HttpMessageConvertersAutoConfiguration,\

org.springframework.boot.autoconfigure.web.MultipartAutoConfiguration,\

org.springframework.boot.autoconfigure.web.ServerPropertiesAutoConfiguration,\

org.springframework.boot.autoconfigure.web.WebClientAutoConfiguration,\

org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration,\

org.springframework.boot.autoconfigure.websocket.WebSocketAutoConfiguration,\

org.springframework.boot.autoconfigure.websocket.WebSocketMessagingAutoConfiguration,\

org.springframework.boot.autoconfigure.webservices.WebServicesAutoConfiguratio

@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;

}

@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");

@Conditional扩展注解

作用（判断是否满足当前指定条件）

@ConditionalOnJava

系统的java版本是否符合要求

@ConditionalOnBean

容器中存在指定Bean；

@ConditionalOnMissingBean

容器中不存在指定Bean；

@ConditionalOnExpression

满足SpEL表达式指定

@ConditionalOnClass

系统中有指定的类

@ConditionalOnMissingClass

系统中没有指定的类

@ConditionalOnSingleCandidate

容器中只有一个指定的Bean，或者这个Bean是首选Bean

@ConditionalOnProperty

系统中指定的属性是否有指定的值

@ConditionalOnResource

类路径下是否存在指定资源文件

@ConditionalOnWebApplication

当前是web环境

@ConditionalOnNotWebApplication

当前不是web环境

@ConditionalOnJndi

JNDI存在指定项

========================

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' (OnClassCondition)