天天看点
返回

第五章：SpringBoot自动配置

作者：源码解析

太卷了！现在面试上来就问SpringBoot源码实现，CRUD工程师能招架得住吗今晚这节SpringBoot直播课千万不能错过，听完就能掌握SpringBoot源码，征服面试官

demo代码：

https://gitee.com/xqh_1_0/spring-boot.git

配置文件到底怎么写？

Spring的所有配置参数

自动配置原理很关键

1、自动配置原理

1）、SpringBoot启动的时候加载主配置类，开启自动配置功能，@EnableAutoConfiguration

2）、@EnableAutoConfiguration 作用：

  • 利用AutoConfigurationImportSelector给容器中导入一些组件？
  • 可以查看selectImports()方法的内容
  • 获取候选的配置 
List<String> configurations = this.getCandidateConfigurations(annotationMetadata, attributes);
  • 扫描类路径下的 
SpringFactoriesLoader.loadFactoryNames(）
  扫描所有jar包类路径下的 MATA-INF/spring.factories
  把扫描到的这些文件的内容包装成properties对象
  从properties中获取到EnableAutoConfiguration.class类（类名）对应的值，然后把他们添加到容器中

将类路径下 MATE-INF/spring.factories里面配置的所有的EnableAutoConfiguration的值加入到了容器中；

3）、每一个自动配置类进行自动配置功能；

4）、以HttpEncodingAutoConfiguration 为例

@Configuration //表示是一个配置类，以前编写的配置文件一样，也可以给容器中添加组件
@EnableConfigurationProperties({HttpEncodingProperties.class})//启动指定类的Configurationproperties功能；将配置文件中的值和HttpEncodingProperties绑定起来了；并把HttpEncodingProperties加入ioc容器中
@ConditionalOnWebApplication//根据不同的条件，进行判断，如果满足条件，整个配置类里面的配置就会失效，判断是否为web应用；
(
    type = Type.SERVLET
)
@ConditionalOnClass({CharacterEncodingFilter.class})//判断当前项目有没有这个类，解决乱码的过滤器
@ConditionalOnProperty(
    prefix = "spring.http.encoding",
    value = {"enabled"},
    matchIfMissing = true
)//判断配置文件是否存在某个配置 spring.http.encoding，matchIfMissing = true如果不存在也是成立，即使不配置也生效
public class HttpEncodingAutoConfiguration {
   //给容器添加组件，这个组件的值需要从properties属性中获取
    private final HttpEncodingProperties properties;
	//只有一个有参数构造器情况下，参数的值就会从容器中拿
    public HttpEncodingAutoConfiguration(HttpEncodingProperties properties) {
        this.properties = properties;
    }

    @Bean
    @ConditionalOnMissingBean
    public CharacterEncodingFilter characterEncodingFilter() {
        CharacterEncodingFilter filter = new OrderedCharacterEncodingFilter();
        filter.setEncoding(this.properties.getCharset().name());
        filter.setForceRequestEncoding(this.properties.shouldForce(org.springframework.boot.autoconfigure.http.HttpEncodingProperties.Type.REQUEST));
        filter.setForceResponseEncoding(this.properties.shouldForce(org.springframework.boot.autoconfigure.http.HttpEncodingProperties.Type.RESPONSE));
        return filter;
    }

5）、所有在配置文件中能配置的属性都是在xxxProperties类中封装着；配置文件能配置什么就可以参照某个功能对应的这个属性类

@ConfigurationProperties(prefix = "spring.http.encoding")//从配置文件中的值进行绑定和bean属性进行绑定
public class HttpEncodingProperties {

根据当前不同条件判断，决定这个配置类是否生效？

一旦这个配置类生效；这个配置类会给容器添加各种组件；这些组件的属性是从对应的properties中获取的，这些类里面的每个属性又是和配置文件绑定的

2、所有的自动配置组件

每一个xxxAutoConfiguration这样的类都是容器中的一个组件，都加入到容器中；

作用：用他们做自动配置

# 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.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.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.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.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.Neo4jRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.solr.SolrRepositoriesAutoConfiguration,\
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.jest.JestAutoConfiguration,\
org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration,\
org.springframework.boot.autoconfigure.freemarker.FreeMarkerAutoConfiguration,\
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.groovy.template.GroovyTemplateAutoConfiguration,\
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.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.orm.jpa.HibernateJpaAutoConfiguration,\
org.springframework.boot.autoconfigure.quartz.QuartzAutoConfiguration,\
org.springframework.boot.autoconfigure.reactor.core.ReactorCoreAutoConfiguration,\
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.sendgrid.SendGridAutoConfiguration,\
org.springframework.boot.autoconfigure.session.SessionAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.client.OAuth2ClientAutoConfiguration,\
org.springframework.boot.autoconfigure.solr.SolrAutoConfiguration,\
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.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

3、精髓：

1）、SpringBoot启动会加载大量的自动配置类

2）、我们看我们需要的功能有没有SpringBoot默认写好的默认配置类；

3）、如果有在看这个自动配置类中配置了哪些组件；（只要我们要用的组件有，我们需要再来配置）

4）、给容器中自动配置添加组件的时候，会从properties类中获取属性。我们就可以在配置文件中指定这些属性的值

xxxAutoConfiguration:自动配置类；

给容器中添加组件

xxxProperties:封装配置文件中的属性；

跟之前的Person类一样，配置文件中值加入bean中

4、细节

1、@Conditional派生注解

利用Spring注解版原生的@Conditional作用

作用：必须是@Conditional指定的条件成立，才给容器中添加组件，配置配里面的所有内容才生效；

@Conditional派生注解 作用（判断是否满足当前指定条件）
@ConditionalOnJava 系统的java版本是否符合要求
@ConditionalOnBean 容器中存在指定Bean
@ConditionalOnMissBean 容器中不存在指定Bean
@ConditionalOnExpression 满足spEL表达式
@ConditionalOnClass 系统中有指定的类
@ConditionalOnMissClass 系统中没有指定的类
@ConditionalOnSingleCandidate 容器中只有一个指定的Bean,或者这个Bean是首选Bean
@ConditionalOnProperty 系统中指定的属性是否有指定的值
@ConditionalOnResource 类路径下是否存在指定的资源文件
@ConditionalOnWebApplication 当前是web环境
@ConditionalOnNotWebApplication 当前不是web环境
@ConditionalOnJndi JNDI存在指定项

2、自动配置报告

自动配置类必须在一定条件下生效

我们可以通过启用debug=true属性，配置文件，打印自动配合报告，这样就可以知道自动配置类生效

debug=true

自动配置报告

============================

CONDITIONS EVALUATION REPORT
============================


Positive matches:（启动的，匹配成功的）
-----------------

   CodecsAutoConfiguration matched:
      - @ConditionalOnClass found required class 'org.springframework.http.codec.CodecConfigurer'; @ConditionalOnMissingClass did not find unwanted class (OnClassCondition)
        ......
        
 Negative matches:（没有启动的，没有匹配成功的）
-----------------

   ActiveMQAutoConfiguration:
      Did not match:
         - @ConditionalOnClass did not find required classes 'javax.jms.ConnectionFactory', 'org.apache.activemq.ActiveMQConnectionFactory' (OnClassCondition)
.....
自动配置 配置 spring pring ring
上一篇: iOS Jenkins自动化打包 上传fir、蒲公英、邮件、钉钉提醒一、环境配置二、环境配置
下一篇: python本地发布到服务器_使用pycharm在本地开发并实时同步到服务器

继续阅读