springboot_day3

 3.15

1.配置文件占位符

2.profile多环境支撑

3.配置文件加载位置

4.自动配置原理

1.配置文件占位符

#随机数
#${random.value} ${random.int} ${random.long}
#${random.int(10)} ${random.int[1024,65536]}
#占位符取之前配置的值，如果没有可以是用：指定默认值
person.dog.name=${person.lastname:hello}_dog

2.profile多环境支撑

  1)多profile文件

我们在主配置文件编写的时候，文件名可以是 application-{profile}.properties/yml

默认使用application.properties的配置

  2)激活指定profile

  （1）yml支持多文档块方式

server:
  port: 8080
spring:
  profiles:
    active: dev
---
server:
  port: 8082
spring:
  profiles: dev
---
server:
  port: 8083
spring:
  profiles: prod
---

通过

spring:
    profiles:
       active: dev

将端口号指定为dev环境下的端口号8082

  （2)通过properties文件

在resources下，建立application-dev.properties,在该文件下写入server.port=8082

在配置文件中application.properties指定激活 spring.profiles.active=dev

   运行程序可以看到 端口号已经改为dev环境下的端口号8082

   2020-03-15 00:24:31.964  INFO 22619 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8082 (http) with context path ''

  （3）在program arguments下写入--spring.profiles.active=dev

端口号已经改为dev环境下的端口号8082

(4)调节虚拟机参数 在VM options写入 -Dspring.profiles.active=dev 指定属于dev环境

3.配置文件加载位置

springboot启动会扫描以下位置的application.properties或者application.yml文件作为其默认的配置文件

-file:./config/

-file:./

-classpath:/config/

-classpath:/

以上是按照优先级从高到低的顺序，所有位置的文件都会被加载，互补配置，高优先级配置内容会覆盖低优先级配置内容。

4.自动配置原理

配置文件能配置的属性：

官方文档

https://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#common-application-properties

springboot精髓：

1）springboot启动会加载大量的自动的配置类

2）看我们需要的功能有没有springboot默认写好的自动配置类

3）如果有，我们再来看这个自动配置类中配置了哪些组件（只要要用的组件有，就不需要再来配置了）

4）给容器中自动配置类添加组件的时候，会从properties类中获取某些属性，可以在配置文件中指定这些属性的值

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作用：

       利用AutoConfigurationImportSelector给容器中导入一些组件

       

结合2.0.0版本的springboot源码：

进入@EnableAutoConfiguration，再进入@Import({AutoConfigurationImportSelector.class})

可以看到：

public String[] selectImports(AnnotationMetadata annotationMetadata) {
        if (!this.isEnabled(annotationMetadata)) {
            return NO_IMPORTS;
        } else {
            try {
                AutoConfigurationMetadata autoConfigurationMetadata = AutoConfigurationMetadataLoader.loadMetadata(this.beanClassLoader);
                AnnotationAttributes attributes = this.getAttributes(annotationMetadata);

//获取候选的配置

List<String> configurations = this.getCandidateConfigurations(annotationMetadata, attributes); configurations = this.removeDuplicates(configurations); configurations = this.sort(configurations, autoConfigurationMetadata); Set<String> exclusions = this.getExclusions(annotationMetadata, attributes); this.checkExcludedClasses(configurations, exclusions); configurations.removeAll(exclusions); configurations = this.filter(configurations, autoConfigurationMetadata); this.fireAutoConfigurationImportEvents(configurations, exclusions); return StringUtils.toStringArray(configurations); } catch (IOException var6) { throw new IllegalStateException(var6); } } }

进入getCandidateConfigurations，看到：

protected List<String> getCandidateConfigurations(AnnotationMetadata metadata, AnnotationAttributes attributes) {

List<String> configurations = SpringFactoriesLoader.loadFactoryNames(this.getSpringFactoriesLoaderFactoryClass(), this.getBeanClassLoader()); Assert.notEmpty(configurations, "No auto configuration classes found in META-INF/spring.factories. If you are using a custom packaging, make sure that file is correct."); return configurations; }

进入SpringFactoriesLoader，看到：

扫描jar包类路径下的META-INF/spring.factories

  public static final String FACTORIES_RESOURCE_LOCATION = "META-INF/spring.factories";

把扫描到的这些文件扫描成properties对象，从properties中获取到EnableAutoConfiguration.class类对应的值，然后把他们添加到容器中

    private static Map<String, List<String>> loadSpringFactories(@Nullable ClassLoader classLoader) {
        MultiValueMap<String, String> result = (MultiValueMap)cache.get(classLoader);
        if (result != null) {
            return result;
        } else {
            try {
                Enumeration<URL> urls = classLoader != null ? classLoader.getResources("META-INF/spring.factories") : ClassLoader.getSystemResources("META-INF/spring.factories");
                LinkedMultiValueMap result = new LinkedMultiValueMap();

                while(urls.hasMoreElements()) {
                    URL url = (URL)urls.nextElement();
                    UrlResource resource = new UrlResource(url);
                    Properties properties = PropertiesLoaderUtils.loadProperties(resource);
                    Iterator var6 = properties.entrySet().iterator();

                    while(var6.hasNext()) {
                        Entry<?, ?> entry = (Entry)var6.next();
                        List<String> factoryClassNames = Arrays.asList(StringUtils.commaDelimitedListToStringArray((String)entry.getValue()));
                        result.addAll((String)entry.getKey(), factoryClassNames);
                    }
                }

                cache.put(classLoader, result);
                return result;
            } catch (IOException var9) {
                throw new IllegalArgumentException("Unable to load factories from location [META-INF/spring.factories]", var9);
            }
        }
    }

打开下面目录 可以查看EnableAutoConfiguration中的值

/Users/mac/.m2/repository/org/springframework/boot/spring-boot-autoconfigure/2.0.0.RELEASE/spring-boot-autoconfigure-2.0.0.RELEASE.jar!/META-INF/spring.factories

每一个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

# 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）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//这是一个配置类和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HttpEncodingProperties类的，并把
HttpEncodingProperties加入到IOC容器中

ConfigurationProperties功能，将配置文件中对应的值和HttpEncodingAutoConfiguration绑定起来了
@ConditionalOnWebApplication//spring底层@Conditional注解，根据不同的条件，如果满足指定条件，则整个配置类里面的配置就会生效
(
    type = Type.SERVLET
)
@ConditionalOnClass({CharacterEncodingFilter.class})
@ConditionalOnProperty(
    prefix = "spring.http.encoding",
    value = {"enabled"},
    matchIfMissing = true
)
public class HttpEncodingAutoConfiguration {

根据当前不同的条件判断，决定这个配置类是否生效，如果生效给容器中添加一个组件，这个组件中的某些值需要从properties中获取

public class HttpEncodingAutoConfiguration {

//该值已经和springboot的配置文件映射了

private final HttpEncodingProperties properties; public HttpEncodingAutoConfiguration(HttpEncodingProperties properties) { this.properties = properties;//只有一个有参构造器情况下，参数的值会从容器中拿 }

    @Bean
    @ConditionalOnMissingBean({CharacterEncodingFilter.class})
    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属性类

@ConfigurationProperties(
    prefix = "spring.http.encoding"//从配置文件中获取指定的值和bean的属性进行绑定
)
public class HttpEncodingProperties {

 所以，当这个配置类生效，这个配置类就会给容器中添加各种组件，这些组件的属性是从对应的properties类中获取的，而这些类中的每一个属性又和配置文件绑定。