springboot04-配置文件加載位置

一、配置文件加載位置：

• spring boot啓動會掃描以下位置的application.properties或者application.yml文件作爲Spring boot的默認配置文件。

  1、file:./config/ ：與src同一文件,是最高優先級

  2、file:./

  3、classpath:/config/

  4、classpath:/

  • 以上是按照優先級從高到低的順序排列，如果在高優先級和低優先級同時存在，會用高優先級去覆蓋低優先級。

  • Spring-Boot會從四個配置文件中全部加載，並形成互補態。形成並集的形態。

  我們還可以用spring.config.location=絕對路徑來改變默認的配置文件位置。

  項目打包好以後，我們可以使用命令行參數的形式，添加新的指定配置文件位置，來形成更大的互補配置。我們不需要重新來打包配置，方便便捷。

二、自動配置原理：

配置文件的屬性和參照：https://docs.spring.io/spring-boot/docs/2.2.5.RELEASE/reference/html/appendix-application-properties.html#common-application-properties

自動配置原理：

1）、SpringBoot啓動的時候加載主配置類，開啓自動配置功能 @EnableAutoConfiguration；

2）、掃描所有jar包中的spring.factories中配置的所有enableautoConfiguration的值全部加載到容器中。

# AutoConfigureCache auto-configuration imports
org.springframework.boot.test.autoconfigure.core.AutoConfigureCache=\
org.springframework.boot.autoconfigure.cache.CacheAutoConfiguration

# AutoConfigureDataJdbc auto-configuration imports
org.springframework.boot.test.autoconfigure.data.jdbc.AutoConfigureDataJdbc=\
org.springframework.boot.autoconfigure.data.jdbc.JdbcRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration,\
org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration

# AutoConfigureDataJpa auto-configuration imports
org.springframework.boot.test.autoconfigure.orm.jpa.AutoConfigureDataJpa=\
org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration,\
org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration,\
org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration

# AutoConfigureDataLdap auto-configuration imports
org.springframework.boot.test.autoconfigure.data.ldap.AutoConfigureDataLdap=\
org.springframework.boot.autoconfigure.data.ldap.LdapRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.ldap.LdapAutoConfiguration,\
org.springframework.boot.autoconfigure.ldap.embedded.EmbeddedLdapAutoConfiguration

# AutoConfigureDataMongo auto-configuration imports
org.springframework.boot.test.autoconfigure.data.mongo.AutoConfigureDataMongo=\
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.mongo.MongoAutoConfiguration,\
org.springframework.boot.autoconfigure.mongo.MongoReactiveAutoConfiguration,\
org.springframework.boot.autoconfigure.mongo.embedded.EmbeddedMongoAutoConfiguration

# AutoConfigureDataNeo4j auto-configuration imports
org.springframework.boot.test.autoconfigure.data.neo4j.AutoConfigureDataNeo4j=\
org.springframework.boot.autoconfigure.data.neo4j.Neo4jDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.neo4j.Neo4jRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration

# AutoConfigureDataRedis auto-configuration imports
org.springframework.boot.test.autoconfigure.data.redis.AutoConfigureDataRedis=\
org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration,\
org.springframework.boot.autoconfigure.data.redis.RedisRepositoriesAutoConfiguration

# AutoConfigureJdbc auto-configuration imports
org.springframework.boot.test.autoconfigure.jdbc.AutoConfigureJdbc=\
org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration,\
org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration

# AutoConfigureTestDatabase auto-configuration imports
org.springframework.boot.test.autoconfigure.jdbc.AutoConfigureTestDatabase=\
org.springframework.boot.test.autoconfigure.jdbc.TestDatabaseAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration

# AutoConfigureJooq auto-configuration imports
org.springframework.boot.test.autoconfigure.jooq.AutoConfigureJooq=\
org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration,\
org.springframework.boot.autoconfigure.jooq.JooqAutoConfiguration,\
org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration,\
org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration

# AutoConfigureJson auto-configuration imports
org.springframework.boot.test.autoconfigure.json.AutoConfigureJson=\
org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration,\
org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration,\
org.springframework.boot.autoconfigure.jsonb.JsonbAutoConfiguration

# AutoConfigureJsonTesters auto-configuration imports
org.springframework.boot.test.autoconfigure.json.AutoConfigureJsonTesters=\
org.springframework.boot.test.autoconfigure.json.JsonTestersAutoConfiguration,\
org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration,\
org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration,\
org.springframework.boot.autoconfigure.jsonb.JsonbAutoConfiguration

# AutoConfigureWebClient auto-configuration imports
org.springframework.boot.test.autoconfigure.web.reactive.AutoConfigureWebTestClient=\
org.springframework.boot.autoconfigure.security.reactive.ReactiveSecurityAutoConfiguration,\
org.springframework.boot.autoconfigure.security.reactive.ReactiveUserDetailsServiceAutoConfiguration,\
org.springframework.boot.test.autoconfigure.web.reactive.WebTestClientAutoConfiguration

# AutoConfigureWebFlux auto-configuration imports
org.springframework.boot.test.autoconfigure.web.reactive.AutoConfigureWebFlux=\
org.springframework.boot.autoconfigure.context.MessageSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.freemarker.FreeMarkerAutoConfiguration,\
org.springframework.boot.autoconfigure.http.codec.CodecsAutoConfiguration,\
org.springframework.boot.autoconfigure.mustache.MustacheAutoConfiguration,\
org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration,\
org.springframework.boot.autoconfigure.validation.ValidationAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.WebFluxAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.error.ErrorWebFluxAutoConfiguration

# AutoConfigureMockMvc auto-configuration imports
org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc=\
org.springframework.boot.test.autoconfigure.web.servlet.MockMvcAutoConfiguration,\
org.springframework.boot.test.autoconfigure.web.servlet.MockMvcWebClientAutoConfiguration,\
org.springframework.boot.test.autoconfigure.web.servlet.MockMvcWebDriverAutoConfiguration,\
org.springframework.boot.autoconfigure.security.servlet.SecurityAutoConfiguration,\
org.springframework.boot.autoconfigure.security.servlet.UserDetailsServiceAutoConfiguration,\
org.springframework.boot.test.autoconfigure.web.servlet.MockMvcSecurityConfiguration

# AutoConfigureMockRestServiceServer
org.springframework.boot.test.autoconfigure.web.client.AutoConfigureMockRestServiceServer=\
org.springframework.boot.test.autoconfigure.web.client.MockRestServiceServerAutoConfiguration

# AutoConfigureRestDocs auto-configuration imports
org.springframework.boot.test.autoconfigure.restdocs.AutoConfigureRestDocs=\
org.springframework.boot.test.autoconfigure.restdocs.RestDocsAutoConfiguration

# AutoConfigureTestEntityManager auto-configuration imports
org.springframework.boot.test.autoconfigure.orm.jpa.AutoConfigureTestEntityManager=\
org.springframework.boot.test.autoconfigure.orm.jpa.TestEntityManagerAutoConfiguration

# AutoConfigureWebClient auto-configuration imports
org.springframework.boot.test.autoconfigure.web.client.AutoConfigureWebClient=\
org.springframework.boot.test.autoconfigure.web.client.WebClientRestTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration,\
org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration,\
org.springframework.boot.autoconfigure.http.codec.CodecsAutoConfiguration,\
org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration,\
org.springframework.boot.autoconfigure.jsonb.JsonbAutoConfiguration,\
org.springframework.boot.autoconfigure.web.client.RestTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.function.client.WebClientAutoConfiguration

# AutoConfigureWebMvc auto-configuration imports
org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureWebMvc=\
org.springframework.boot.autoconfigure.context.MessageSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.data.web.SpringDataWebAutoConfiguration,\
org.springframework.boot.autoconfigure.freemarker.FreeMarkerAutoConfiguration,\
org.springframework.boot.autoconfigure.groovy.template.GroovyTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration,\
org.springframework.boot.autoconfigure.hateoas.HypermediaAutoConfiguration,\
org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration,\
org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration,\
org.springframework.boot.autoconfigure.jsonb.JsonbAutoConfiguration,\
org.springframework.boot.autoconfigure.mustache.MustacheAutoConfiguration,\
org.springframework.boot.autoconfigure.task.TaskExecutionAutoConfiguration,\
org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration,\
org.springframework.boot.autoconfigure.validation.ValidationAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.error.ErrorMvcAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration

# DefaultTestExecutionListenersPostProcessors
org.springframework.boot.test.context.DefaultTestExecutionListenersPostProcessor=\
org.springframework.boot.test.autoconfigure.SpringBootDependencyInjectionTestExecutionListener$PostProcessor

# Spring Test ContextCustomizerFactories
org.springframework.test.context.ContextCustomizerFactory=\
org.springframework.boot.test.autoconfigure.OverrideAutoConfigurationContextCustomizerFactory,\
org.springframework.boot.test.autoconfigure.filter.TypeExcludeFiltersContextCustomizerFactory,\
org.springframework.boot.test.autoconfigure.properties.PropertyMappingContextCustomizerFactory,\
org.springframework.boot.test.autoconfigure.web.servlet.WebDriverContextCustomizerFactory

# Test Execution Listeners
org.springframework.test.context.TestExecutionListener=\
org.springframework.boot.test.autoconfigure.restdocs.RestDocsTestExecutionListener,\
org.springframework.boot.test.autoconfigure.web.client.MockRestServiceServerResetTestExecutionListener,\
org.springframework.boot.test.autoconfigure.web.servlet.MockMvcPrintOnlyOnFailureTestExecutionListener,\
org.springframework.boot.test.autoconfigure.web.servlet.WebDriverTestExecutionListener

3）、每一個這樣的xxxAutoConfiguration類都是容器中的一個組件，都加入到容器中，用他們來做自動配置；

4）、舉例一個：

@Configuration(
    proxyBeanMethods = false
)//這個是一個配置類
@EnableConfigurationProperties({HttpProperties.class})
//自動配置類開啓：
//啓動指定類的ConfigurationProperties功能；將配置文件中對應的值和 HttpProperties 的class綁定起來。
@ConditionalOnWebApplication(
    type = Type.SERVLET
)
@ConditionalOnClass({CharacterEncodingFilter.class})
//Spring底層@Conditional註解:根據不同的條件，如果滿足指定的條件，整個配置類裏面的配置就會生效。
//CharacterEncodingFilter：SpringMVC中進行亂碼解決的過濾器。
@ConditionalOnProperty(
    prefix = "spring.http.encoding",
    value = {"enabled"},
    matchIfMissing = true
)
//判斷配置文件中是否存在 "spring.http.encoding.enabled"；如果不存在，判斷也是成立的( matchIfMissing = true)
//無論如何這個都會成立

//當所有的配置都開始生效後：下面的操作將全部生效

private final Encoding properties;

//把配置文件中的值賦值給properties
public HttpEncodingAutoConfiguration(HttpProperties properties) {
        this.properties = properties.getEncoding();
    }

@Bean				 //給容器中添加一個組件
@ConditionalOnMissingBean
public CharacterEncodingFilter characterEncodingFilter() {
	CharacterEncodingFilter filter = new OrderedCharacterEncodingFilter();
	//我們把從配置文件獲取的值設置爲編碼形式 
    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;
}

根據當前不同的條件判斷，決定這個配置類是否生效。

一旦這個配置類生效，這個配置類就會給容器中添加各種組件；這些組件的屬性和都是從對應的properties類中取到的，而這些類又是和每一個properties的配置文件所綁定的。

Spring-Boot的精髓：

• SpringBoot啓動會產生大量的自動配置的類；
• 我們看我們所需要的功能有沒有SpringBoot中所包含的寫好的自動配置類；
• 我們再來看這個自動配置類中到底配置了哪些組件（只要SpringBoot中自動配置好了的組件，我們就可以直接拿來用就可以了，不需要重新配置）；
• 給容器中添加組件的時候，會從properties類中獲取某些屬性，我們就可以在配置文件中修改這些指定的屬性即可。

**xxxAutoConfiguration：**自動配置類；

給容器中添加組件

**xxxProperties：**封裝配置文件中相關屬性；

使用ctrl+N 進行快捷搜索 自動配置類：

來查看存在哪些自動配置類。

三、@Conditional派生註解（Spring註解：@Conditional作用）

作用：必須是@Conditional指定的條件成立，才能給容器中添加該組件，配置裏的所有內容才生效。

自動配置類必須在一定的條件下才能生效。

現在我們需要知道的是：哪些自動配置類生效了。

方法：

我們可以通過 debug=true屬性；來讓控制檯打印自動配置報告；

這樣我們就可以知道自動配置了哪些配置類生效了。

我們來運行一下：

自動配置報告就給我們打印了我們生效了的配置類：

啓用的配置類：Positive matches:

Positive matches:
-----------------

   AopAutoConfiguration matched:
      - @ConditionalOnProperty (spring.aop.auto=true) matched (OnPropertyCondition)

   AopAutoConfiguration.ClassProxyingConfiguration matched:
      - @ConditionalOnMissingClass did not find unwanted class 'org.aspectj.weaver.Advice' (OnClassCondition)
      - @ConditionalOnProperty (spring.aop.proxy-target-class=true) matched (OnPropertyCondition)

   DispatcherServletAutoConfiguration matched:
      - @ConditionalOnClass found required class 'org.springframework.web.servlet.DispatcherServlet' (OnClassCondition)
      - found 'session' scope (OnWebApplicationCondition)

   DispatcherServletAutoConfiguration.DispatcherServletConfiguration matched:
      - @ConditionalOnClass found required class 'javax.servlet.ServletRegistration' (OnClassCondition)
      - Default DispatcherServlet did not find dispatcher servlet beans (DispatcherServletAutoConfiguration.DefaultDispatcherServletCondition)

   DispatcherServletAutoConfiguration.DispatcherServletRegistrationConfiguration matched:
      - @ConditionalOnClass found required class 'javax.servlet.ServletRegistration' (OnClassCondition)
      - DispatcherServlet Registration did not find servlet registration bean (DispatcherServletAutoConfiguration.DispatcherServletRegistrationCondition)
.......
....
...

沒啓用的配置類：Negative matches:

Negative matches:
-----------------

   ActiveMQAutoConfiguration:
      Did not match:
         - @ConditionalOnClass did not find required class 'javax.jms.ConnectionFactory' (OnClassCondition)

   AopAutoConfiguration.AspectJAutoProxyingConfiguration:
      Did not match:
         - @ConditionalOnClass did not find required class 'org.aspectj.weaver.Advice' (OnClassCondition)

   ArtemisAutoConfiguration:
      Did not match:
         - @ConditionalOnClass did not find required class 'javax.jms.ConnectionFactory' (OnClassCondition)

   BatchAutoConfiguration:
      Did not match:
         - @ConditionalOnClass did not find required class 'org.springframework.batch.core.launch.JobLauncher' (OnClassCondition)

   CacheAutoConfiguration:
      Did not match:
         - @ConditionalOnBean (types: org.springframework.cache.interceptor.CacheAspectSupport; SearchStrategy: all) did not find any beans of type org.springframework.cache.interceptor.CacheAspectSupport (OnBeanCondition)
      Matched:
         - @ConditionalOnClass found required class 'org.springframework.cache.CacheManager' (OnClassCondition)

   CacheAutoConfiguration.CacheManagerEntityManagerFactoryDependsOnPostProcessor:
      Did not match:
         - @ConditionalOnClass did not find required class 'org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean' (OnClassCondition)
         - Ancestor org.springframework.boot.autoconfigure.cache.CacheAutoConfiguration did not match (ConditionEvaluationReport.AncestorsMatchedCondition)