SpringBoot自学好几天 中途开始写笔记 外部配置加载顺序 自动配置的原理 20190118

其他 2019-01-19 23:58:23 阅读次数: 0
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1. 外部配置加载顺序

SpringBoot也可以从以下位置加载配置，优先级从高到低，高优先级配置覆盖低优先级配置，如果有不同内容，所有配置会形成互补配置
1.命令行参数
java -jar spring-boot-01-config-0.0.1-SNAPSHOT.jar --server.port=8087 --server.context-path=/test
Spring升级版本后 server.port 改为了server.servlet.context-path
2.来自java:comp/env的JNDI属性
3.java系统属性
4.操作系统环境变量
5.RandomValuePropertySource配置的random. 属性
由jar包外向jar包内进行寻找；
如果指定了profile 会优先加载带profile 再来加载不带profile
6.jar包外部的application-{profile}.properties或application.yml(带spring.profile)配置文件
7.jar包内部的application-{profile}.properties或application.yml(带spring.profile)配置文件
8.jar包外部的application.properties或application.yml(不带spring.profile)配置文件
9.jar包内部的application.properties或application.yml(不带spring.profile)配置文件
10.@configuration注解类上的@PropertySource属性
11.通过SpringApplication.setDefaultProperties指定的默认属性
参考官方文档 Externalized Configuration 如果读起来比较费力 可以用谷歌直接翻译了

2.自动配置的原理

配置文件能配置什么？
参考官方文档 Common application properties：https://docs.spring.io/spring-boot/docs/2.1.2.RELEASE/reference/htmlsingle/#common-application-properties
自动配置原理
1）SpringBoot启动的时候 加载主配置类，开启了自动配置功能
@EnableAutoConfiguration
2）@EnableAutoConfiguration注解的作用

  • 利用AutoConfigurationImportSelector给容器中导入组件
  • 查看getAutoConfigurationEntry->getCandidateConfigurations->
List<String> configurations = SpringFactoriesLoader.loadFactoryNames(this.getSpringFactoriesLoaderFactoryClass(), this.getBeanClassLoader());
//1.扫描所有jar包META-INF/spring.factories  把扫描到的这些文件的内容包装成Properties对象,从Properties对象  
//2.从Properties中获取到EnableAutoConfiguration.class 类名对应的值 然后把他们添加在容器中

一句话总结就是：将META-INF/spring.factories里面配置的EnableAutoConfiguration的值 加入到了容器中

# 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.CloudServiceConnectorsAutoConfiguration,\
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.jdbc.JdbcRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration,\
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.elasticsearch.rest.RestClientAutoConfiguration,\
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.SecurityRequestMatcherProviderAutoConfiguration,\
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.servlet.OAuth2ClientAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.client.reactive.ReactiveOAuth2ClientAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.resource.servlet.OAuth2ResourceServerAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.resource.reactive.ReactiveOAuth2ResourceServerAutoConfiguration,\
org.springframework.boot.autoconfigure.solr.SolrAutoConfiguration,\
org.springframework.boot.autoconfigure.task.TaskExecutionAutoConfiguration,\
org.springframework.boot.autoconfigure.task.TaskSchedulingAutoConfiguration,\
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.ClientHttpConnectorAutoConfiguration,\
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,\
org.springframework.boot.autoconfigure.webservices.client.WebServiceTemplateAutoConfiguration

每一个xxxAutoConfiguration类 都是容器中的一个组件，都加入到容器中，他们的作用就是来做自动配置的
3)每一个自动配置类 进行自动配置功能
4）以HttpEncodingAutoConfiguration为例 解释自动配置原理

@Configuration //表示这是一个配置类，与之前的配置文件一样，也可以给容器中添加组件
@EnableConfigurationProperties({HttpProperties.class})//启动指定类（HttpProperties）的ConfigurationProperties功能  将配置文件对应的值与HttpProperties绑定  并把HttpProperties加入到ioc容器中
@ConditionalOnWebApplication(type = Type.SERVLET)//Spring底层 @Conditional注解=>根据不同的条件 ，如果满足指定的条件，整个配置类里边的配置才会生效   ConditionalOnWebApplication就是判断当前项目是不是Web应用
@ConditionalOnClass({CharacterEncodingFilter.class})//判断jar包里边有没有CharacterEncodingFilter这个类   CharacterEncodingFilter是SpringMvc中解决乱码的拦截器
@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.enabled） 如果存在就根据他的值判断true和false如果不存在这个属性默认是true
//即使配置文件中不配置spring.http.encoding.enabled 也是默认生效的
public class HttpEncodingAutoConfiguration {
	//他已经和SpringBoot的配置文件映射了  他是HttpProperties的静态内部类
 	private final Encoding properties;
 	//只有一个有参构造器的情况下，参数的值就会从容器中拿  上边的EnableConfigurationProperties 会把HttpProperties 放到容器中
    public HttpEncodingAutoConfiguration(HttpProperties properties) {
        this.properties = properties.getEncoding();
    }
    @Bean //给容器添加组件 ，这个组件的某些值需要从properties中获取
    @ConditionalOnMissingBean//容器中没有这个组件 才会进行配置
    public CharacterEncodingFilter characterEncodingFilter() {
        CharacterEncodingFilter filter = new OrderedCharacterEncodingFilter();
        filter.setEncoding(this.properties.getCharset().name());
        filter.setForceRequestEncoding(this.properties.shouldForce(org.springframework.boot.autoconfigure.http.HttpProperties.Encoding.Type.REQUEST));
        filter.setForceResponseEncoding(this.properties.shouldForce(org.springframework.boot.autoconfigure.http.HttpProperties.Encoding.Type.RESPONSE));
        return filter;
    }

根据当前不同的条件判断，决定这个配置类是否生效(判断都成功才生效),一旦这个配置类生效，这个配置类就会给容器添加组件，这些组件的属性是从对应的peoperties类中获取的，而这些peoperties类里边的属性又是和配置文件绑定的
5）所有在配置文件中能配置的属性都是在xxxProperties中封装的属性；配置文件能配置什么，就可以参照某一个功能对应的属性类

@ConfigurationProperties(prefix = "spring.http")//这个注解意思是 从配置文件中获取指定的值 和bean的属性进行绑定  这个bean中有什么属性 配置文件就能配置什么值
public class HttpProperties {

精髓：
1）SpringBoot启动会加载大量的配置类
2）我们需要的功能有没有SpringBoot默认写好的配置类
3）如果有，我们看这些配置类中配置了哪些组件，如果包含我们用的组件，我们就不需要再进行配置
4）给容器中自动配置类添加组件的时候，会从properties中获取某些属性，这些属性可以在配置文件中指定这些属性的值；

xxxAutoconfiguration:自动配置类，给容器添加组件
xxxProperties:封装配置文件中相关属性

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