Spring Boot 自動(dòng)配置
來(lái)看下 spring boot中自動(dòng)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() 可以排除一些自動(dòng)配置的內(nèi)容
- excludeName 通過(guò)名稱排除自動(dòng)配置內(nèi)容
再來(lái)看下腿堤，@EnableAutoConfiguration 是怎么處理自動(dòng)配置的呢脆丁？
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(lái)看下 AutoConfigurationImportSelector 句喷，主要是 接口的 ImportSelector 的實(shí)現(xiàn)
@Override
public String[] selectImports(AnnotationMetadata annotationMetadata) {
if (!isEnabled(annotationMetadata)) {
return NO_IMPORTS;
}
try {
//1丐膝、 自動(dòng)配置的元數(shù)據(jù) spring-autocomfigure-metadata.properties
// 自動(dòng)配置的開(kāi)啟條件
AutoConfigurationMetadata autoConfigurationMetadata = AutoConfigurationMetadataLoader
.loadMetadata(this.beanClassLoader);
AnnotationAttributes attributes = getAttributes(annotationMetadata);
// 獲取設(shè)置的自動(dòng)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(dòng)配置列表，可以通過(guò) 注解@EnableAutoConfiguration 的exclude和
// 配置文件設(shè)置 spring.autoconfigure.exclude key的值
Set<String> exclusions = getExclusions(annotationMetadata, attributes);
checkExcludedClasses(configurations, exclusions);
configurations.removeAll(exclusions);
// 通過(guò) spring-autocomfigure-metadata.properties ConditionOnClass 條件進(jìn)行過(guò)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 的處理方式踢京，會(huì)解析 @Import 里的接口 ImportSelector 返回的所有配置類,那是怎么配置的呢跨算，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 {
}
從上面可以看到轻要，有很多的@ConditionalOn**的注解，我們來(lái)看下 ConditionEvaluator這個(gè) 條件計(jì)算器，會(huì)去計(jì)算出當(dāng)前這個(gè)配置類 是否要開(kāi)啟舀射，而這些 @ConditionalOn** 是依賴于 @Conditional 這個(gè)注解窘茁，如 @ConditionalOnBean 最終是通過(guò) Condition 接口來(lái)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(xiàng)目，但大部分情況下脆烟，并不是所以的項(xiàng)目都會(huì)啟用山林，通過(guò) Condition和@Conditional 來(lái)判斷條件
- 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(huán)境中是否存在特定的配置項(xiàng)
@ConditionalOnProperty - 配置環(huán)境中指定的配置項(xiàng)是否存在指定的值
禁用配置
當(dāng)前 也是可以禁用某些我們不想要的默認(rèn)配置，如上面加載時(shí)說(shuō)到邢羔，會(huì)排除一些配置(exclude)
- 設(shè)置
@EnableAutoConfiguration的exclude 配置 - 在配置文件增加 spring.autoconfigure.exclude 配置
