Spring Boot 自動配置
來看下 spring boot中自動配置的注解
@SuppressWarnings("deprecation")@Target(ElementType.TYPE)@Retention(RetentionPolicy.RUNTIME)@Documented@Inherited@AutoConfigurationPackage@Import(EnableAutoConfigurationImportSelector.class)public @interface EnableAutoConfiguration { String ENABLED_OVERRIDE_PROPERTY = "spring.boot.enableautoconfiguration"; /** * Exclude specific auto-configuration classes such that they will never be applied. * @return the classes to exclude */ Class<?>[] exclude() default {}; /** * Exclude specific auto-configuration class names such that they will never be * applied. * @return the class names to exclude * @since 1.3.0 */ String[] excludeName() default {};}
再來看下, @EnableAutoConfiguration
是怎么處理自動配置的呢?
注意到@Import(EnableAutoConfigurationImportSelector.class)
public class EnableAutoConfigurationImportSelector extends AutoConfigurationImportSelector { @Override protected boolean isEnabled(AnnotationMetadata metadata) { if (getClass().equals(EnableAutoConfigurationImportSelector.class)) { return getEnvironment().getProperty( EnableAutoConfiguration.ENABLED_OVERRIDE_PROPERTY, Boolean.class, true); } return true; }}}
再來看下 AutoConfigurationImportSelector
,主要是 接口的 ImportSelector
的實現
@Override public String[] selectImports(AnnotationMetadata annotationMetadata) { if (!isEnabled(annotationMetadata)) { return NO_IMPORTS; } try { //1、 自動配置的元數據 spring-autocomfigure-metadata.properties // 自動配置的開啟條件 AutoConfigurationMetadata autoConfigurationMetadata = AutoConfigurationMetadataLoader .loadMetadata(this.beanClassLoader); AnnotationAttributes attributes = getAttributes(annotationMetadata); // 獲取設置的自動配置列表 spring.factories List<String> configurations = getCandidateConfigurations(annotationMetadata, attributes); configurations = removeDuplicates(configurations); configurations = sort(configurations, autoConfigurationMetadata); // 獲取要排除的自動配置列表,可以通過 注解@EnableAutoConfiguration 的exclude和 // 配置文件設置 spring.autoconfigure.exclude key的值 Set<String> exclusions = getExclusions(annotationMetadata, attributes); checkExcludedClasses(configurations, exclusions); configurations.removeAll(exclusions); // 通過 spring-autocomfigure-metadata.properties ConditionOnClass 條件進行過濾 configurations = filter(configurations, autoConfigurationMetadata); fireAutoConfigurationImportEvents(configurations, exclusions); return configurations.toArray(new String[configurations.size()]); } catch (IOException ex) { throw new IllegalStateException(ex); } }
看下 spring.factories 文件
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,/org.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.ElasticsearchRepositoriesAutoConfiguration,/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,/
再看下 spring framework中 ConfigurationClassParser
的處理方式,會解析 @Import
里的接口 ImportSelector
返回的所有配置類,那是怎么配置的呢,如 JpaRepositoriesAutoConfiguration
@Configuration@ConditionalOnBean(DataSource.class)@ConditionalOnClass(JpaRepository.class)@ConditionalOnMissingBean({ JpaRepositoryFactoryBean.class, JpaRepositoryConfigExtension.class })@ConditionalOnProperty(prefix = "spring.data.jpa.repositories", name = "enabled", havingValue = "true", matchIfMissing = true)@Import(JpaRepositoriesAutoConfigureRegistrar.class)@AutoConfigureAfter(HibernateJpaAutoConfiguration.class)public class JpaRepositoriesAutoConfiguration {}
從上面可以看到,有很多的@ConditionalOn**
的注解,我們來看下 ConditionEvaluator
這個 條件計算器,會去計算出當前這個配置類 是否要開啟,而這些 @ConditionalOn**
是依賴于 @Conditional
這個注解,如 @ConditionalOnBean
最終是通過 Condition 接口來作條件選擇
@Target({ ElementType.TYPE, ElementType.METHOD })@Retention(RetentionPolicy.RUNTIME)@Documented@Conditional(OnBeanCondition.class)public @interface ConditionalOnBean { /** * The class type of bean that should be checked. The condition matches when any of * the classes specified is contained in the {@link ApplicationContext}. * @return the class types of beans to check */ Class<?>[] value() default {}; /** * The class type names of bean that should be checked. The condition matches when any * of the classes specified is contained in the {@link ApplicationContext}. * @return the class type names of beans to check */ String[] type() default {}; /** * The annotation type decorating a bean that should be checked. The condition matches * when any of the annotations specified is defined on a bean in the * {@link ApplicationContext}. * @return the class-level annotation types to check */ Class<? extends Annotation>[] annotation() default {}; /** * The names of beans to check. The condition matches when any of the bean names * specified is contained in the {@link ApplicationContext}. * @return the name of beans to check */ String[] name() default {}; /** * Strategy to decide if the application context hierarchy (parent contexts) should be * considered. * @return the search strategy */ SearchStrategy search() default SearchStrategy.ALL;}
Spring boot 的autoconfigure 是囊括了所有可以和spring 整合的項目,但大部分情況下,并不是所以的項目都會啟用,通過 Condition和@Conditional 來判斷條件
@ConditionalOnClass
@ConditionalOnBean
@ConditionalOnProperty
禁用配置
當前 也是可以禁用某些我們不想要的默認配置,如上面加載時說到,會排除一些配置(exclude)
@EnableAutoConfiguration
的exclude 配置以上就是本文的全部內容,希望對大家的學習有所幫助,也希望大家多多支持VeVb武林網。
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