12-SpringBoot自动装配属性配置
springboot中最重要的就是自动配置，主要作用是由注解@SpringbootApplication来发挥的，该注解中的@EnableAutoConfiguration，再到其中的@Import(AutoConfigurationImportSelector.class)，作用就是获取候选的配置类，其中这些候选的配置类信息是从spring-boot-autoconfigure-2.4.3.jar/META-INF/spring.factories这个文件中加载的，该文件就包含了spring项目所有的配置类。我们打开这个factories文件，将其中的自动配置类文档块复制出来，如下
# 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.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.solr.SolrRepositoriesAutoConfiguration,\
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.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.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.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.ReactiveWebServerFactoryAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.WebFluxAutoConfiguration,\
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
我们打开其中的HttpEncodingAutoConfiguration查看源码，具体分析如下
//这个注解表示这是一个配置类，其中的参数的值为false，表示这个配置类不是单例的
@Configuration(
proxyBeanMethods = false
)
//自动配置属性，表示将ServerProperties.class对应的对象作为组件放进容器中，这样ServerProperties这个类才能和yaml配置文件关联
@EnableConfigurationProperties({ServerProperties.class})
//Spring底层注解：根据不同条件来判断当前配置类是否生效，就是是否满足作为组件被放进容器中的条件
@ConditionalOnWebApplication(
type = ConditionalOnWebApplication.Type.SERVLET//这里需要满足当前项目必须是web项目，该配置类才会生效
)
@ConditionalOnClass({CharacterEncodingFilter.class})//这里要求系统中必须有CharacterEncodingFilter这个类
@ConditionalOnProperty(//是否满足下面的一些配置
prefix = "server.servlet.encoding",
value = {"enabled"},
matchIfMissing = true
)
public class HttpEncodingAutoConfiguration {
private final Encoding properties;//一个编码属性，就是用ServerProperties进行赋值
public HttpEncodingAutoConfiguration(ServerProperties properties) {
this.properties = properties.getServlet().getEncoding();
}
@Bean
@ConditionalOnMissingBean
public CharacterEncodingFilter characterEncodingFilter() {
CharacterEncodingFilter filter = new OrderedCharacterEncodingFilter();
filter.setEncoding(this.properties.getCharset().name());
filter.setForceRequestEncoding(this.properties.shouldForce(org.springframework.boot.web.servlet.server.Encoding.Type.REQUEST));
filter.setForceResponseEncoding(this.properties.shouldForce(org.springframework.boot.web.servlet.server.Encoding.Type.RESPONSE));
return filter;
}
@Bean
public org.springframework.boot.autoconfigure.web.servlet.HttpEncodingAutoConfiguration.LocaleCharsetMappingsCustomizer localeCharsetMappingsCustomizer() {
return new org.springframework.boot.autoconfigure.web.servlet.HttpEncodingAutoConfiguration.LocaleCharsetMappingsCustomizer(this.properties);
}
static class LocaleCharsetMappingsCustomizer implements WebServerFactoryCustomizer<ConfigurableServletWebServerFactory>, Ordered {
private final Encoding properties;
LocaleCharsetMappingsCustomizer(Encoding properties) {
this.properties = properties;
}
public void customize(ConfigurableServletWebServerFactory factory) {
if (this.properties.getMapping() != null) {
factory.setLocaleCharsetMappings(this.properties.getMapping());
}
}
public int getOrder() {
return 0;
}
}
}
我们在打开ServerProperties查看其源码，部分如下
@ConfigurationProperties(
prefix = "server",
ignoreUnknownFields = true
)
public class ServerProperties {
private Integer port;
private InetAddress address;
@NestedConfigurationProperty
private final ErrorProperties error = new ErrorProperties();
private ServerProperties.ForwardHeadersStrategy forwardHeadersStrategy;
private String serverHeader;
private DataSize maxHttpHeaderSize = DataSize.ofKilobytes(8L);
private Shutdown shutdown;
@NestedConfigurationProperty
private Ssl ssl;
@NestedConfigurationProperty
private final Compression compression;
@NestedConfigurationProperty
private final Http2 http2;
private final ServerProperties.Servlet servlet;
private final ServerProperties.Tomcat tomcat;
private final ServerProperties.Jetty jetty;
private final ServerProperties.Netty netty;
private final ServerProperties.Undertow undertow;
public ServerProperties() {
this.shutdown = Shutdown.IMMEDIATE;
this.compression = new Compression();
this.http2 = new Http2();
this.servlet = new ServerProperties.Servlet();
this.tomcat = new ServerProperties.Tomcat();
this.jetty = new ServerProperties.Jetty();
this.netty = new ServerProperties.Netty();
this.undertow = new ServerProperties.Undertow();
}
...
可以看到是由@ConfigurationProperties注解修饰的，对应到配置文件的前缀是prefix = "server"
我们就可以在properties或yaml配置文件中用server前缀来设置改属性类的字段值了。
也就是说，自动装配原理，@SpringBootApplication将所有候选配置类进行加载，具体的这些配置类的属性值由@EnableAutoConfigurationProperties这个注解中的XxxProperties类中的属性决定，而这个XxxProperties又和配置文件相关联，到时我们需要修改就可以使用对应前缀的字段名进行修改就行了。
所以配置文件中应该怎么写，需要我们到自动配置类中找到相应配置类，找到对应的XxxProperties类，查看前缀和字段就可以了。
- SpringBoot 启动会加载大量的自动配置类，
- 我们看其中是否有我们需要的功能有没有在SpringBoot默认写好的自动配置类中
- 然后我们再查看自动配置类中配置 了哪些组件，如果我们需要的组件已经有了，就不需要我们手动配置类
- 给容器中自动配置类添加组件的时候，会从XxxProperties类中获取对应的属性，我们只需要在配置文件中指定这些属性值就可以了
- 如果我们想知道哪些组件被加载到容器中，哪些组件没被加载，以及具体的原因，我们可以在配置文件中添加：DEBUG=true在执行的时候打印自动配置类的生效信息
