【SpringBoot】SpringBoot 配置這一篇文章就夠了

霓裳夢竹發表於2020-05-24
Spring Boot

SpringBoot 配置檔案

一、配置檔案

SpringBoot使用一個全域性的配置檔案，配置檔名是固定的；

  • application.properties

  • application.yml

配置檔案的作用：修改SpringBoot自動配置的預設值；SpringBoot在底層都給我們自動配置好；

YAML（YAML Ain't Markup Language）

YAML A Markup Language：是一個標記語言

YAML isn't Markup Language：不是一個標記語言；

標記語言：

以前的配置檔案；大多都使用的是 xxxx.xml檔案；

YAML：以資料為中心，比json、xml等更適合做配置檔案；

YAML：配置例子

server:
	port: 8081

xml:

<server> 
    <port>8081</port> 
</server>

二、YAML語法

1、基本語法

k:(空格)v：表示一對鍵值對（空格必須有）；

以空格的縮排來控制層級關係；只要是左對齊的一列資料，都是同一個層級的

server: 
	port: 8081
	path: /hello

屬性和值也是大小寫敏感；

2、值的寫法

2.1 字面量：普通的值（數字，字串，布林）

k: v：字面直接來寫；

字串預設不用加上單引號或者雙引號；

""：雙引號；不會轉義字串裡面的特殊字元；特殊字元會作為本身想表示的意思

name: "zhangsan \n lisi"：輸出；zhangsan 換行 lisi

''：單引號；會轉義特殊字元，特殊字元最終只是一個普通的字串資料

name: ‘zhangsan \n lisi’：輸出；zhangsan \n lisi

2.2 物件、Map（屬性和值）（鍵值對）：

k: v：在下一行來寫物件的屬性和值的關係；注意縮排

物件還是k: v的方式

friends:
		lastName: sang
		age: 18

行內寫法

friends: {lastName: sang,age: 18}
2.3 陣列（List Set）

用- 值表示陣列中的一個元素

pets:
	- cat
	- dog
	- pig

行內寫法

pets: [cat,dog,pig]

三、@ConfigurationProperties配置檔案值注入

1.pom.xml中新增依賴

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <version>2.3.0.RELEASE</version>
            <optional>true</optional>
</dependency>

書寫配置檔案的時候會提示

2.配置檔案

person:
  lastName: sang
  age: 18
  boss: false
  maps: {k1: v1,k2: v2}
  lists:
    - li
    - san
  dog:
    name: wang
    age: 12

如果使用properties檔案中文亂碼的話需要修改檔案的編碼

3.JavaBean:

package com.slp.springboot02config.bean;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

import java.util.List;
import java.util.Map;

/**
 * @ClassName Person
 * @Description 將配置檔案中配置的每一個屬性的值，對映到這個元件中
 * ConfigurationProperties：告訴SpringBoot將本類中的所有屬性和配置檔案中的相關的配置進行繫結；
 * prefis = "person":配置檔案中哪個下面的所有屬性一一對映
 *
 * 只有這個組價是容器中的元件，才能使用容器提供的@ConfigurationProperties功能
 * @Author sanglp
 * @Date 2020/5/22 17:42
 * @Version 1.0
 **/
@Component
@ConfigurationProperties(prefix = "person")
public class Person {
    private String lastName;
    private int age;
    private Boolean boss;
    private List<Object> lists;
    private Map<String,Object> maps;
    private Dog dog;

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public Boolean getBoss() {
        return boss;
    }

    public void setBoss(Boolean boss) {
        this.boss = boss;
    }

    public List<Object> getLists() {
        return lists;
    }

    public void setLists(List<Object> lists) {
        this.lists = lists;
    }

    public Map<String, Object> getMaps() {
        return maps;
    }

    public void setMaps(Map<String, Object> maps) {
        this.maps = maps;
    }

    public Dog getDog() {
        return dog;
    }

    public void setDog(Dog dog) {
        this.dog = dog;
    }

    @Override
    public String toString() {
        return "Person{" +
                "lastName='" + lastName + '\'' +
                ", age=" + age +
                ", boss=" + boss +
                ", lists=" + lists +
                ", maps=" + maps +
                ", dog=" + dog +
                '}';
    }
}


package com.slp.springboot02config.bean;

/**
 * @ClassName Dog
 * @Description TODO
 * @Author zixin
 * @Date 2020/5/22 17:44
 * @Version 1.0
 **/
public class Dog {
    private String name;

    private int age;
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}


package com.slp.springboot02config;

import com.slp.springboot02config.bean.Person;
import org.junit.jupiter.api.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

/**
 * 可以在測試期間自動注入
 * RunWith 指定使用Spring處理器而不是junit
 */
@RunWith(SpringRunner.class)
@SpringBootTest
class SpringBoot02ConfigApplicationTests {

    @Autowired
    Person person;
    @Test
    void contextLoads() {
        System.out.println(person);
    }
}

4.結果：

Person{lastName='sang', age=18, boss=false, lists=[li, san], maps={k1=v1, k2=v2}, dog=com.slp.springboot02config.bean.Dog@6fa69af7}

四、@Value獲取值

其它配置和上方一致，只看一下javabean的改變

package com.slp.springboot02config.bean;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import java.util.List;
import java.util.Map;

@Component
public class PersonNew {
    /**
     * <bean class="Person2">
     *     <propertu name="lastName" value="sang"></propertu>
     *     </bean>
     *     person.last-name :對應的是配置檔案中的名稱
     */
    @Value("person.last-name")
    private String lastName;
    @Value("#{11*2}")
    private int age;
    @Value("true")
    private Boolean boss;
    private List<Object> lists;
    private Map<String,Object> maps;
    private Dog dog;

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public Boolean getBoss() {
        return boss;
    }

    public void setBoss(Boolean boss) {
        this.boss = boss;
    }

    public List<Object> getLists() {
        return lists;
    }

    public void setLists(List<Object> lists) {
        this.lists = lists;
    }

    public Map<String, Object> getMaps() {
        return maps;
    }

    public void setMaps(Map<String, Object> maps) {
        this.maps = maps;
    }

    public Dog getDog() {
        return dog;
    }

    public void setDog(Dog dog) {
        this.dog = dog;
    }
}

五、@Value和@ConfigurationProperties注入的區別

@ConfigurationProperties @Value
功能 批量注入配置檔案中的屬性 一個個指定
鬆散繫結 支援 不支援
SPEL 不支援 支援
JSR303資料校驗 支援 不支援 
//JSR303校驗
@Component
@ConfigurationProperties(prefix = "personval")
@Validated
public class PersonValidate {
    @Email
    private String lastName;
}

需要新增jar包

<!--jsr3引數校驗器-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-validation</artifactId>
        </dependency>

六、@PropertySource&@ImportResource

1.@PropertySource

載入指定配置檔案

package com.slp.springboot02config.bean;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.PropertySource;
import org.springframework.stereotype.Component;

@PropertySource(value = {"classpath:person.properties"})
@Component
@ConfigurationProperties(prefix = "personsource")
public class PersonPropertySource {
    private String lastName;

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    @Override
    public String toString() {
        return "PersonPropertySource{" +
                "lastName='" + lastName + '\'' +
                '}';
    }
}

person.properties

personsource.lastName=sang

測試結果

PersonPropertySource{lastName='sang'}

2.@ImportResource

匯入Spring的配置檔案，讓配置檔案中的內容生效

新建一個spring的配置檔案，內容如下

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="helloService" class="com.slp.springboot02config.service.HelloService"></bean>
</beans>

測試Spring容器是否包含這個bean

package com.slp.springboot02config;

import com.slp.springboot02config.bean.Person;
import com.slp.springboot02config.bean.PersonPropertySource;
import org.junit.jupiter.api.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.context.ApplicationContext;
import org.springframework.test.context.junit4.SpringRunner;

/**
 * 可以在測試期間自動注入
 * RunWith 指定使用Spring處理器而不是junit
 */
@RunWith(SpringRunner.class)
@SpringBootTest
class SpringBoot02ConfigApplicationTests {

    @Autowired
    Person person;
    @Autowired
    PersonPropertySource personPropertySource;
    @Autowired
    ApplicationContext ioc ;
    @Test
    void contextLoads() {
        System.out.println(ioc.containsBean("helloService"));
    }

}

輸出結果為false,說明此時裡面還沒有這個bean,說明自己編寫的配置檔案不能自動識別，想讓Spring的配置檔案生效，載入進來，需要將@ImportResource標註在主配置類上，修改啟動類內容為如下

@ImportResource(locations = {"classpath:beans.xml"})
@SpringBootApplication
public class SpringBoot02ConfigApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringBoot02ConfigApplication.class, args);
    }

}

再進行測試則會輸出true，說明載入成功。

但是這樣會很麻煩，加一個就要修改一下，SpringBoot推薦給容器中新增元件的方式:使用全註解的方式(@Bean)

去掉主配置類上的@ImportResource

//@ImportResource(locations = {"classpath:beans.xml"})
@SpringBootApplication
public class SpringBoot02ConfigApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringBoot02ConfigApplication.class, args);
    }

}

新增一個配置類

package com.slp.springboot02config.config;

import com.slp.springboot02config.service.HelloService;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * @Configuration：指明當前類是一個配置類   就是來替代之前的Spring配置檔案
 * 在配置檔案中用<bean></bean>來新增元件
 */
@Configuration
public class MyAppConfig {
    /**
     *  @Bean:將方法的返回值新增到容器中，容器中的元件預設的id就是方法名
     * @return
     */
    @Bean
    public HelloService helloService(){
        return new HelloService();
    }
}

七、配置檔案佔位符

1.隨機數

${random.value}
${random.int}
${random.long}
${random.int(10)}
${random.int[1024,65536]}

2.佔位符獲取之前配置的值，如果沒有可以使用：之後的預設值

person.last-name=sang${random.int}
person.dog.name=${person.hello:hello}_dog

八.Profile

1.多Profile檔案

我們在主配置檔案編寫的時候，檔名可以是application-{profile}.properties/yml

預設使用application.properties的配置

2.yml支援多文件塊方式

server:
  port: 8081
  
spring:
  profiles:
    active: prod
      
---
server:
  port: 8083
spring:
  profiles: dev
  
---
server:
  port: 8084
spring:
  profiles: prod

3. 啟用制定profile

  1. 在配置檔案application.properties中指定
spring.profiles.active=dev

  1. 命令列

    java -jar 專案.jar -spring.profiles.active=dev

  2. 虛擬機器引數

    -Dspring.profiles.active=dev

九 配置檔案載入位置

springboot啟動會掃描以下位置的application.properties或者application.yml檔案作為Spring boot的預設配置檔案

file:./config

file:./

classpath:/config/

classpath:/

優先順序由高到低，高優先順序會覆蓋低優先順序的配置；

SpringBoot從這四個位置全部載入，形成互補；

可以通過spring.config.location來修改預設的配置檔案位置

專案打包好之後我們可以使用命令列引數的形式，啟動專案的時候來指定配置檔案的新位置，指定配置檔案和預設載入的這些配置檔案共同起作用形式形成互補

java -jar spring-boot-02.jar --spring.config.location=D:/application.properties

十、外部配置載入順序

SpringBoot可以從以下位置載入，優先順序由高到低，形成互補。

  1. 命令列引數

    java -jar spring-boot.jar --server.port=8081 --server.context-path=/hello

  2. 來自java:comp:/env的JNDI屬性

  3. java系統屬性（System.getProperties()）

  4. 作業系統環境變數

  5. RandomValuePropertySource配置的random.*屬性值

  6. jar包外部的application-{profile}.properties或application.yml（帶spring.profile）

  7. jar包內部的application-{profile}.properties或application.yml（帶spring.profile）

  8. jar包外部的application-{profile}.properties或application.yml（不帶spring.profile）

  9. jar包內部的application-{profile}.properties或application.yml（不帶spring.profile）

  10. @Configuration註解類上的@PropertySource

  11. 通過SpringApplication.setDefaultProperties指定的預設屬性

十一、自動配置原理

可以配置的元素

1.自動配置原理

1） SpringBoot啟動的時候載入主配置類，開啟了自動配置功能@EnableAutoConfiguration
2）@EnableAutoConfiguration的作用

  • 利用AutoConfigurationImportSelector給容器匯入一些元件

  • 可以檢視selectInports()方法的內容

  • protected AutoConfigurationImportSelector.AutoConfigurationEntry getAutoConfigurationEntry(AnnotationMetadata annotationMetadata) 

Enumeration<URL> urls = classLoader != null ? classLoader.getResources("META-INF/spring.factories") : ClassLoader.getSystemResources("META-INF/spring.factories");

SpringFactoriesLoader.loadFactoryNames()

掃描所有jar包類路徑下META-INF/spring.factories

把掃描到的這些檔案的內容包裝秤properties物件

從properties中獲取到EnableAutoConfiguration.class類對應的值

  • 將類路徑下META-INF/spring.factories裡面配置的所有EnableAutoConfiguration的值加入到容器中

    # Initializers
org.springframework.context.ApplicationContextInitializer=\
org.springframework.boot.autoconfigure.SharedMetadataReaderFactoryContextInitializer,\
org.springframework.boot.autoconfigure.logging.ConditionEvaluationReportLoggingListener

# Application Listeners
org.springframework.context.ApplicationListener=\
org.springframework.boot.autoconfigure.BackgroundPreinitializer

# Auto Configuration Import Listeners
org.springframework.boot.autoconfigure.AutoConfigurationImportListener=\
org.springframework.boot.autoconfigure.condition.ConditionEvaluationReportAutoConfigurationImportListener

# Auto Configuration Import Filters
org.springframework.boot.autoconfigure.AutoConfigurationImportFilter=\
org.springframework.boot.autoconfigure.condition.OnBeanCondition,\
org.springframework.boot.autoconfigure.condition.OnClassCondition,\
org.springframework.boot.autoconfigure.condition.OnWebApplicationCondition

# 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.context.ConfigurationPropertiesAutoConfiguration,\
org.springframework.boot.autoconfigure.context.LifecycleAutoConfiguration,\
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.ElasticsearchDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ReactiveElasticsearchRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ReactiveElasticsearchRestClientAutoConfiguration,\
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.r2dbc.R2dbcDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.r2dbc.R2dbcRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.r2dbc.R2dbcTransactionManagerAutoConfiguration,\
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.ElasticsearchRestClientAutoConfiguration,\
org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration,\
org.springframework.boot.autoconfigure.freemarker.FreeMarkerAutoConfiguration,\
org.springframework.boot.autoconfigure.groovy.template.GroovyTemplateAutoConfiguration,\
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.jersey.JerseyAutoConfiguration,\
org.springframework.boot.autoconfigure.jooq.JooqAutoConfiguration,\
org.springframework.boot.autoconfigure.jsonb.JsonbAutoConfiguration,\
org.springframework.boot.autoconfigure.kafka.KafkaAutoConfiguration,\
org.springframework.boot.autoconfigure.availability.ApplicationAvailabilityAutoConfiguration,\
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.r2dbc.R2dbcAutoConfiguration,\
org.springframework.boot.autoconfigure.rsocket.RSocketMessagingAutoConfiguration,\
org.springframework.boot.autoconfigure.rsocket.RSocketRequesterAutoConfiguration,\
org.springframework.boot.autoconfigure.rsocket.RSocketServerAutoConfiguration,\
org.springframework.boot.autoconfigure.rsocket.RSocketStrategiesAutoConfiguration,\
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.security.rsocket.RSocketSecurityAutoConfiguration,\
org.springframework.boot.autoconfigure.security.saml2.Saml2RelyingPartyAutoConfiguration,\
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

# Failure analyzers
org.springframework.boot.diagnostics.FailureAnalyzer=\
org.springframework.boot.autoconfigure.diagnostics.analyzer.NoSuchBeanDefinitionFailureAnalyzer,\
org.springframework.boot.autoconfigure.flyway.FlywayMigrationScriptMissingFailureAnalyzer,\
org.springframework.boot.autoconfigure.jdbc.DataSourceBeanCreationFailureAnalyzer,\
org.springframework.boot.autoconfigure.jdbc.HikariDriverConfigurationFailureAnalyzer,\
org.springframework.boot.autoconfigure.r2dbc.ConnectionFactoryBeanCreationFailureAnalyzer,\
org.springframework.boot.autoconfigure.session.NonUniqueSessionRepositoryFailureAnalyzer

# Template availability providers
org.springframework.boot.autoconfigure.template.TemplateAvailabilityProvider=\
org.springframework.boot.autoconfigure.freemarker.FreeMarkerTemplateAvailabilityProvider,\
org.springframework.boot.autoconfigure.mustache.MustacheTemplateAvailabilityProvider,\
org.springframework.boot.autoconfigure.groovy.template.GroovyTemplateAvailabilityProvider,\
org.springframework.boot.autoconfigure.thymeleaf.ThymeleafTemplateAvailabilityProvider,\
org.springframework.boot.autoconfigure.web.servlet.JspTemplateAvailabilityProvider

    每一個這樣的xxxAutoCnfiguration類都是容器中的一個元件，都加入到容器中，用他們來做自動配置

3)、每一個自動配置類進行自動配置功能
4) 以HttpEncodingAutoConfiguration為例來解釋自動配置與案例
@Configuration(  //表示這是一個配置類 可以給容器中新增元件
  proxyBeanMethods = false
)
@EnableConfigurationProperties({ServerProperties.class}) //啟用指定類ConfigurationProperties功能  將配置檔案中對應的值和ConfigurationProperties繫結起來
@ConditionalOnWebApplication(
  type = Type.SERVLET
)
@ConditionalOnClass({CharacterEncodingFilter.class})//根據不同的條件，如果滿足指定的條件整改配置類裡面的配置就會生效  判斷當前專案有沒有CharacterEncodingFilter.class這個類
@ConditionalOnProperty(
  prefix = "server.servlet.encoding",
  value = {"enabled"},
  matchIfMissing = true
)//判斷配置檔案中是否存在某個配置 server.servlet.encoding.enable=true如果不存在也是生效的
public class HttpEncodingAutoConfiguration {
  private final Encoding properties;
  //只有一個有參構造器的情況下，引數的值會從容器中拿
  public HttpEncodingAutoConfiguration(ServerProperties properties) {
      this.properties = properties.getServlet().getEncoding();
  }
   @Bean//給容器中新增元件 這個元件的某些值 需要從Properties中獲取
  @ConditionalOnMissingBean
  public CharacterEncodingFilter characterEncodingFilter() {
      CharacterEncodingFilter filter = new OrderedCharacterEncodingFilter();
      filter.setEncoding(this.properties.getCharset().name());
      filter.setForceRequestEncoding(this.properties.shouldForce(org.springframework.boot.web.servlet.server.Encoding.Type.REQUEST));
      filter.setForceResponseEncoding(this.properties.shouldForce(org.springframework.boot.web.servlet.server.Encoding.Type.RESPONSE));
      return filter;
  }

根據當前不同的條件判斷，決定這個配置是否生效？

一旦這個配置類生效，這個配置類就會給容器中新增各種元件；這些元件的屬性是從對應的properties裡中獲取的，這些類裡面的屬性又是和配置檔案繫結的。

5）所有配置檔案中能配置的屬性都是在xxxProperties類中封裝著
@ConfigurationProperties(
  prefix = "server",
  ignoreUnknownFields = true
)//從配置檔案中獲取指定的值和bean的屬性進行繫結
public class ServerProperties {

精髓：

  • SpringBoot啟動會載入大量的自動配置類

  • 我們看我們需要的功能有沒有SpringBoot預設寫好的自動配置類

  • 我們再來看這個自動配置類到底配置了哪些元件

  • 給容器中的自動配置類新增元件的時候，會從properties類中獲取某些屬性，我們就可以在配置檔案中指定這些屬性的至

    2.細節

1)@Conditional派生註解（Spring註解版原生的@Conditional作用）

作用：必須是@Conditional指定的條件成立，才給容器中新增元件，配置檔案中的內容才生效

@Conditional擴充套件註解 作用（判斷是否滿足當前指定條件）
@ConditionalOnJava 系統的java版本是否符合要求
@ConditionalOnBean 容器中存在指定Bean；
@ConditionalOnMissingBean 容器中不存在指定Bean；
@ConditionalOnExpression 滿足SpEL表示式指定
@ConditionalOnClass 系統中有指定的類
@ConditionalOnMissingClass 系統中沒有指定的類
@ConditionalOnSingleCandidate 容器中只有一個指定的Bean，或者這個Bean是首選Bean
@ConditionalOnProperty 系統中指定的屬性是否有指定的值
@ConditionalOnResource 類路徑下是否存在指定資原始檔
@ConditionalOnWebApplication 當前是web環境
@ConditionalOnNotWebApplication 當前不是web環境
@ConditionalOnJndi JNDI存在指定項

我們如何知道哪些自動配置類生效

通過啟用debug=true屬性，來讓控制檯列印自動配置報告

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


Positive matches:  （自動配置類啟用的）
-----------------

   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)
      
Negative matches:  （自動配置類沒有啟用的）
-----------------

   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)

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