Spring Boot 自动配置的实现
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2024-03-31 12:12:46
spring boot 自动配置
来看下 spring boot中自动配置的注解
@suppresswarnings("deprecation")
@ta...
spring boot 自动配置
来看下 spring boot中自动配置的注解
@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 {}; }
- exclude() 可以排除一些自动配置的内容
- excludename 通过名称排除自动配置内容
再来看下, @enableautoconfiguration
是怎么处理自动配置的呢?
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; } } }
再来看下 autoconfigurationimportselector
,主要是 接口的 importselector
的实现
@override public string[] selectimports(annotationmetadata annotationmetadata) { if (!isenabled(annotationmetadata)) { return no_imports; } try { //1、 自动配置的元数据 spring-autocomfigure-metadata.properties // 自动配置的开启条件 autoconfigurationmetadata autoconfigurationmetadata = autoconfigurationmetadataloader .loadmetadata(this.beanclassloader); annotationattributes attributes = getattributes(annotationmetadata); // 获取设置的自动配置列表 spring.factories list<string> configurations = getcandidateconfigurations(annotationmetadata, attributes); configurations = removeduplicates(configurations); configurations = sort(configurations, autoconfigurationmetadata); // 获取要排除的自动配置列表,可以通过 注解@enableautoconfiguration 的exclude和 // 配置文件设置 spring.autoconfigure.exclude key的值 set<string> exclusions = getexclusions(annotationmetadata, attributes); checkexcludedclasses(configurations, exclusions); configurations.removeall(exclusions); // 通过 spring-autocomfigure-metadata.properties conditiononclass 条件进行过滤 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
的处理方式,会解析 @import
里的接口 importselector
返回的所有配置类,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 { }
从上面可以看到,有很多的@conditionalon**
的注解,我们来看下 conditionevaluator
这个 条件计算器,会去计算出当前这个配置类 是否要开启,而这些 @conditionalon**
是依赖于 @conditional
这个注解,如 @conditionalonbean
最终是通过 condition 接口来作条件选择
@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 整合的项目,但大部分情况下,并不是所以的项目都会启用,通过 condition和@conditional 来判断条件
- 判断classpath 是否存在指定的类
@conditionalonclass
- 判断 applicationcontext 中是否存在指定的 bean
@conditionalonbean
- 配置环境中是否存在特定的配置项
@conditionalonproperty
- 配置环境中指定的配置项是否存在指定的值
禁用配置
当前 也是可以禁用某些我们不想要的默认配置,如上面加载时说到,会排除一些配置(exclude)
- 设置
@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内容,希望对大家的学习有所帮助,也希望大家多多支持。
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