springboot04-配置文件加载位置

一、配置文件加载位置：

• spring boot启动会扫描以下位置的application.properties或者application.yml文件作为Spring boot的默认配置文件。

  1、file:./config/ ：与src同一文件,是最高优先级

  2、file:./

  3、classpath:/config/

  4、classpath:/

  • 以上是按照优先级从高到低的顺序排列，如果在高优先级和低优先级同时存在，会用高优先级去覆盖低优先级。

  • Spring-Boot会从四个配置文件中全部加载，并形成互补态。形成并集的形态。

  我们还可以用spring.config.location=绝对路径来改变默认的配置文件位置。

  项目打包好以后，我们可以使用命令行参数的形式，添加新的指定配置文件位置，来形成更大的互补配置。我们不需要重新来打包配置，方便便捷。

二、自动配置原理：

配置文件的属性和参照：https://docs.spring.io/spring-boot/docs/2.2.5.RELEASE/reference/html/appendix-application-properties.html#common-application-properties

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）、扫描所有jar包中的spring.factories中配置的所有enableautoConfiguration的值全部加载到容器中。

# 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）、每一个这样的xxxAutoConfiguration类都是容器中的一个组件，都加入到容器中，用他们来做自动配置；

4）、举例一个：

@Configuration(
    proxyBeanMethods = false
)//这个是一个配置类
@EnableConfigurationProperties({HttpProperties.class})
//自动配置类开启：
//启动指定类的ConfigurationProperties功能；将配置文件中对应的值和 HttpProperties 的class绑定起来。
@ConditionalOnWebApplication(
    type = Type.SERVLET
)
@ConditionalOnClass({CharacterEncodingFilter.class})
//Spring底层@Conditional注解:根据不同的条件，如果满足指定的条件，整个配置类里面的配置就会生效。
//CharacterEncodingFilter：SpringMVC中进行乱码解决的过滤器。
@ConditionalOnProperty(
    prefix = "spring.http.encoding",
    value = {"enabled"},
    matchIfMissing = true
)
//判断配置文件中是否存在 "spring.http.encoding.enabled"；如果不存在，判断也是成立的( matchIfMissing = true)
//无论如何这个都会成立

//当所有的配置都开始生效后：下面的操作将全部生效

private final Encoding properties;

//把配置文件中的值赋值给properties
public HttpEncodingAutoConfiguration(HttpProperties properties) {
        this.properties = properties.getEncoding();
    }

@Bean				 //给容器中添加一个组件
@ConditionalOnMissingBean
public CharacterEncodingFilter characterEncodingFilter() {
	CharacterEncodingFilter filter = new OrderedCharacterEncodingFilter();
	//我们把从配置文件获取的值设置为编码形式 
    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;
}

根据当前不同的条件判断，决定这个配置类是否生效。

一旦这个配置类生效，这个配置类就会给容器中添加各种组件；这些组件的属性和都是从对应的properties类中取到的，而这些类又是和每一个properties的配置文件所绑定的。

Spring-Boot的精髓：

• SpringBoot启动会产生大量的自动配置的类；
• 我们看我们所需要的功能有没有SpringBoot中所包含的写好的自动配置类；
• 我们再来看这个自动配置类中到底配置了哪些组件（只要SpringBoot中自动配置好了的组件，我们就可以直接拿来用就可以了，不需要重新配置）；
• 给容器中添加组件的时候，会从properties类中获取某些属性，我们就可以在配置文件中修改这些指定的属性即可。

**xxxAutoConfiguration：**自动配置类；

给容器中添加组件

**xxxProperties：**封装配置文件中相关属性；

使用ctrl+N 进行快捷搜索 自动配置类：

来查看存在哪些自动配置类。

三、@Conditional派生注解（Spring注解：@Conditional作用）

作用：必须是@Conditional指定的条件成立，才能给容器中添加该组件，配置里的所有内容才生效。

自动配置类必须在一定的条件下才能生效。

现在我们需要知道的是：哪些自动配置类生效了。

方法：

我们可以通过 debug=true属性；来让控制台打印自动配置报告；

这样我们就可以知道自动配置了哪些配置类生效了。

我们来运行一下：

自动配置报告就给我们打印了我们生效了的配置类：

启用的配置类：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)
.......
....
...

没启用的配置类：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)