spring boot 自動配置
來看下 spring boot中自動配置的注解
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@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 {};} |
- exclude() 可以排除一些自動配置的內容
- excludename 通過名稱排除自動配置內容
再來看下， @enableautoconfiguration 是怎么處理自動配置的呢？
注意到@import(enableautoconfigurationimportselector.class)
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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
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@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
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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
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@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
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@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
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判斷classpath 是否存在指定的類
@conditionalonclass -
判斷 applicationcontext 中是否存在指定的 bean
@conditionalonbean -
配置環境中是否存在特定的配置項
@conditionalonproperty - 配置環境中指定的配置項是否存在指定的值
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)
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設置
@enableautoconfiguration的exclude 配置 - 在配置文件增加 spring.autoconfigure.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服務器之家。
原文鏈接：https://www.jianshu.com/p/7261521394e7
