SpringBoot学习之路---SpringBoot的版本仲裁中心

我们知道SpringBoot能通过启动器(starters)来自动帮助我们管理maven依赖，但是里面不同的maven坐标都有不同的版本，不仅如此，还需要考虑许多maven依赖坐标之间会不会有冲突，这就需要协调好各个版本之间的关系了。

---

这些SpringBoot都帮我们管理好了。
它是在哪儿管理的呢?

---

答案就在我们项目的pom文件中:

<parent>
        <groupId>org.springframework.bootgroupId>
        <artifactId>spring-boot-starter-parentartifactId>
        <version>2.2.5.RELEASEversion>
        <relativePath/> 
    parent>

我们通过Spring Initializr生成一个项目时，会在pom文件中自动帮我们加入这个parent元素，说明咱们的SpringBoot依赖于某个父项目，我们点进去一看究竟

<parent>
    <groupId>org.springframework.bootgroupId>
    <artifactId>spring-boot-dependenciesartifactId>
    <version>2.2.5.RELEASEversion>
    <relativePath>../../spring-boot-dependenciesrelativePath>
  parent>

里面有个重要的元素，它还依赖个父项目(禁止俄罗斯套娃 ),咱们再点进去看看

结果发现一个properties元素，里面定义了很多maven坐标的版本。

<properties>
    <activemq.version>5.15.11activemq.version>
    <antlr2.version>2.7.7antlr2.version>
    <appengine-sdk.version>1.9.78appengine-sdk.version>
    <artemis.version>2.10.1artemis.version>
    <aspectj.version>1.9.5aspectj.version>
    <assertj.version>3.13.2assertj.version>
    <atomikos.version>4.0.6atomikos.version>
    <awaitility.version>4.0.2awaitility.version>
    <bitronix.version>2.1.4bitronix.version>
    <build-helper-maven-plugin.version>3.0.0build-helper-maven-plugin.version>
    <byte-buddy.version>1.10.8byte-buddy.version>
    <caffeine.version>2.8.1caffeine.version>
    <cassandra-driver.version>3.7.2cassandra-driver.version>
    <classmate.version>1.5.1classmate.version>
    <commons-codec.version>1.13commons-codec.version>
    <commons-dbcp2.version>2.7.0commons-dbcp2.version>
    <commons-lang3.version>3.9commons-lang3.version>
    <commons-pool.version>1.6commons-pool.version>
    <commons-pool2.version>2.7.0commons-pool2.version>
    <couchbase-cache-client.version>2.1.0couchbase-cache-client.version>
    <couchbase-client.version>2.7.12couchbase-client.version>
    <db2-jdbc.version>11.5.0.0db2-jdbc.version>
    <dependency-management-plugin.version>1.0.9.RELEASEdependency-management-plugin.version>
    <derby.version>10.14.2.0derby.version>
    <dropwizard-metrics.version>4.1.3dropwizard-metrics.version>
    <ehcache.version>2.10.6ehcache.version>
    <ehcache3.version>3.8.1ehcache3.version>
    <elasticsearch.version>6.8.6elasticsearch.version>
    <embedded-mongo.version>2.2.0embedded-mongo.version>
    <exec-maven-plugin.version>1.6.0exec-maven-plugin.version>
    <flatten-maven-plugin.version>1.1.0flatten-maven-plugin.version>
    <flyway.version>6.0.8flyway.version>
    <freemarker.version>2.3.29freemarker.version>
    <git-commit-id-plugin.version>3.0.1git-commit-id-plugin.version>
    <glassfish-el.version>3.0.3glassfish-el.version>
    <glassfish-jaxb.version>2.3.2glassfish-jaxb.version>
    <groovy.version>2.5.9groovy.version>
    <gson.version>2.8.6gson.version>
    <h2.version>1.4.200h2.version>
    <hamcrest.version>2.1hamcrest.version>
    <hazelcast.version>3.12.6hazelcast.version>
    <hazelcast-hibernate5.version>1.3.2hazelcast-hibernate5.version>
    <hibernate.version>5.4.12.Finalhibernate.version>
    <hibernate-validator.version>6.0.18.Finalhibernate-validator.version>
    <hikaricp.version>3.4.2hikaricp.version>
    <hsqldb.version>2.5.0hsqldb.version>
    <htmlunit.version>2.36.0htmlunit.version>
    <httpasyncclient.version>4.1.4httpasyncclient.version>
    <httpclient.version>4.5.11httpclient.version>
    <httpcore.version>4.4.13httpcore.version>
    <infinispan.version>9.4.18.Finalinfinispan.version>
    <influxdb-java.version>2.15influxdb-java.version>
    <jackson.version>2.10.2.20200130jackson.version>
    <jackson-bom.version>${jackson.version}jackson-bom.version>
    <jakarta-activation.version>1.2.2jakarta-activation.version>
    <jakarta-annotation.version>1.3.5jakarta-annotation.version>
    <jakarta-jms.version>2.0.3jakarta-jms.version>
    <jakarta-json.version>1.1.6jakarta-json.version>
    <jakarta-json-bind.version>1.0.2jakarta-json-bind.version>
    <jakarta-mail.version>1.6.4jakarta-mail.version>
    <jakarta-persistence.version>2.2.3jakarta-persistence.version>
    <jakarta-servlet.version>4.0.3jakarta-servlet.version>
    <jakarta-servlet-jsp.version>2.3.5jakarta-servlet-jsp.version>
    <jakarta-servlet-jsp-jstl.version>1.2.7jakarta-servlet-jsp-jstl.version>
    <jakarta-transaction.version>1.3.3jakarta-transaction.version>
    <jakarta-validation.version>2.0.2jakarta-validation.version>
    <jakarta-websocket.version>1.1.2jakarta-websocket.version>
    <jakarta-ws-rs.version>2.1.6jakarta-ws-rs.version>
    <jakarta-xml-bind.version>2.3.2jakarta-xml-bind.version>
    <jakarta-xml-ws.version>2.3.2jakarta-xml-ws.version>
    <janino.version>3.1.0janino.version>
    <javax-activation.version>1.2.0javax-activation.version>
    <javax-annotation.version>1.3.2javax-annotation.version>
    <javax-cache.version>1.1.1javax-cache.version>
    <javax-jaxb.version>2.3.1javax-jaxb.version>
    <javax-jaxws.version>2.3.1javax-jaxws.version>
    <javax-jms.version>2.0.1javax-jms.version>
    <javax-json.version>1.1.4javax-json.version>
    <javax-jsonb.version>1.0javax-jsonb.version>
    <javax-mail.version>1.6.2javax-mail.version>
    <javax-money.version>1.0.3javax-money.version>
    <javax-persistence.version>2.2javax-persistence.version>
    <javax-transaction.version>1.3javax-transaction.version>
    <javax-validation.version>2.0.1.Finaljavax-validation.version>
    <javax-websocket.version>1.1javax-websocket.version>
    <jaxen.version>1.2.0jaxen.version>
    <jaybird.version>3.0.8jaybird.version>
    <jboss-logging.version>3.4.1.Finaljboss-logging.version>
    <jboss-transaction-spi.version>7.6.0.Finaljboss-transaction-spi.version>
    <jdom2.version>2.0.6jdom2.version>
    <jedis.version>3.1.0jedis.version>
    <jersey.version>2.29.1jersey.version>
    <jest.version>6.3.1jest.version>
    <jetty.version>9.4.26.v20200117jetty.version>
    <jetty-el.version>8.5.49jetty-el.version>
    <jetty-jsp.version>2.2.0.v201112011158jetty-jsp.version>
    <jetty-reactive-httpclient.version>1.0.3jetty-reactive-httpclient.version>
    <jmustache.version>1.15jmustache.version>
    <jna.version>4.5.2jna.version>
    <joda-time.version>2.10.5joda-time.version>
    <johnzon.version>${johnzon-jsonb.version}johnzon.version>
    <johnzon-jsonb.version>1.2.3johnzon-jsonb.version>
    <jolokia.version>1.6.2jolokia.version>
    <jooq.version>3.12.4jooq.version>
    <jsonassert.version>1.5.0jsonassert.version>
    <json-path.version>2.4.0json-path.version>
    <jstl.version>1.2jstl.version>
    <jtds.version>1.3.1jtds.version>
    <junit.version>4.12junit.version>
    <junit-jupiter.version>5.5.2junit-jupiter.version>
    <kafka.version>2.3.1kafka.version>
    <kotlin.version>1.3.61kotlin.version>
    <kotlin-coroutines.version>1.3.3kotlin-coroutines.version>
    <lettuce.version>5.2.2.RELEASElettuce.version>
    <liquibase.version>3.8.7liquibase.version>
    <log4j2.version>2.12.1log4j2.version>
    <logback.version>1.2.3logback.version>
    <lombok.version>1.18.12lombok.version>
    <mariadb.version>2.4.4mariadb.version>
    <maven-antrun-plugin.version>1.8maven-antrun-plugin.version>
    <maven-assembly-plugin.version>3.1.1maven-assembly-plugin.version>
    <maven-clean-plugin.version>3.1.0maven-clean-plugin.version>
    <maven-compiler-plugin.version>3.8.1maven-compiler-plugin.version>
    <maven-dependency-plugin.version>3.1.1maven-dependency-plugin.version>
    <maven-deploy-plugin.version>2.8.2maven-deploy-plugin.version>
    <maven-enforcer-plugin.version>3.0.0-M3maven-enforcer-plugin.version>
    <maven-failsafe-plugin.version>2.22.2maven-failsafe-plugin.version>
    <maven-help-plugin.version>3.2.0maven-help-plugin.version>
    <maven-install-plugin.version>2.5.2maven-install-plugin.version>
    <maven-invoker-plugin.version>3.2.1maven-invoker-plugin.version>
    <maven-jar-plugin.version>3.1.2maven-jar-plugin.version>
    <maven-javadoc-plugin.version>3.1.1maven-javadoc-plugin.version>
    <maven-resources-plugin.version>3.1.0maven-resources-plugin.version>
    <maven-shade-plugin.version>3.2.2maven-shade-plugin.version>
    <maven-site-plugin.version>3.8.2maven-site-plugin.version>
    <maven-source-plugin.version>3.1.0maven-source-plugin.version>
    <maven-surefire-plugin.version>2.22.2maven-surefire-plugin.version>
    <maven-war-plugin.version>3.2.3maven-war-plugin.version>
    <micrometer.version>1.3.5micrometer.version>
    <mimepull.version>1.9.12mimepull.version>
    <mockito.version>3.1.0mockito.version>
    <mongodb.version>3.11.2mongodb.version>
    <mongo-driver-reactivestreams.version>1.12.0mongo-driver-reactivestreams.version>
    <mssql-jdbc.version>7.4.1.jre8mssql-jdbc.version>
    <mysql.version>8.0.19mysql.version>
    <nekohtml.version>1.9.22nekohtml.version>
    <neo4j-ogm.version>3.2.9neo4j-ogm.version>
    <netty.version>4.1.45.Finalnetty.version>
    <netty-tcnative.version>2.0.29.Finalnetty-tcnative.version>
    <nio-multipart-parser.version>1.1.0nio-multipart-parser.version>
    <ojdbc.version>19.3.0.0ojdbc.version>
    <okhttp3.version>3.14.7okhttp3.version>
    <pooled-jms.version>1.0.6pooled-jms.version>
    <postgresql.version>42.2.10postgresql.version>
    <prometheus-pushgateway.version>0.7.0prometheus-pushgateway.version>
    <quartz.version>2.3.2quartz.version>
    <querydsl.version>4.2.2querydsl.version>
    <rabbit-amqp-client.version>5.7.3rabbit-amqp-client.version>
    <reactive-streams.version>1.0.3reactive-streams.version>
    <reactor-bom.version>Dysprosium-SR5reactor-bom.version>
    <rest-assured.version>3.3.0rest-assured.version>
    <rsocket.version>1.0.0-RC6rsocket.version>
    <rxjava.version>1.3.8rxjava.version>
    <rxjava2.version>2.2.18rxjava2.version>
    <rxjava-adapter.version>1.2.1rxjava-adapter.version>
    <saaj-impl.version>1.5.1saaj-impl.version>
    <selenium.version>3.141.59selenium.version>
    <selenium-htmlunit.version>2.36.0selenium-htmlunit.version>
    <sendgrid.version>4.4.5sendgrid.version>
    <servlet-api.version>4.0.1servlet-api.version>
    <slf4j.version>1.7.30slf4j.version>
    <snakeyaml.version>1.25snakeyaml.version>
    <solr.version>8.2.0solr.version>
    <spring-amqp.version>2.2.5.RELEASEspring-amqp.version>
    <spring-batch.version>4.2.1.RELEASEspring-batch.version>
    <spring-cloud-connectors.version>2.0.7.RELEASEspring-cloud-connectors.version>
    <spring-data-releasetrain.version>Moore-SR5spring-data-releasetrain.version>
    <spring-framework.version>5.2.4.RELEASEspring-framework.version>
    <spring-hateoas.version>1.0.3.RELEASEspring-hateoas.version>
    <spring-integration.version>5.2.4.RELEASEspring-integration.version>
    <spring-kafka.version>2.3.6.RELEASEspring-kafka.version>
    <spring-ldap.version>2.3.2.RELEASEspring-ldap.version>
    <spring-restdocs.version>2.0.4.RELEASEspring-restdocs.version>
    <spring-retry.version>1.2.5.RELEASEspring-retry.version>
    <spring-security.version>5.2.2.RELEASEspring-security.version>
    <spring-session-bom.version>Corn-SR1spring-session-bom.version>
    <spring-ws.version>3.0.8.RELEASEspring-ws.version>
    <sqlite-jdbc.version>3.28.0sqlite-jdbc.version>
    <sun-mail.version>${jakarta-mail.version}sun-mail.version>
    <thymeleaf.version>3.0.11.RELEASEthymeleaf.version>
    <thymeleaf-extras-data-attribute.version>2.0.1thymeleaf-extras-data-attribute.version>
    <thymeleaf-extras-java8time.version>3.0.4.RELEASEthymeleaf-extras-java8time.version>
    <thymeleaf-extras-springsecurity.version>3.0.4.RELEASEthymeleaf-extras-springsecurity.version>
    <thymeleaf-layout-dialect.version>2.4.1thymeleaf-layout-dialect.version>
    <tomcat.version>9.0.31tomcat.version>
    <unboundid-ldapsdk.version>4.0.14unboundid-ldapsdk.version>
    <undertow.version>2.0.29.Finalundertow.version>
    <versions-maven-plugin.version>2.7versions-maven-plugin.version>
    <webjars-hal-browser.version>3325375webjars-hal-browser.version>
    <webjars-locator-core.version>0.41webjars-locator-core.version>
    <wsdl4j.version>1.6.3wsdl4j.version>
    <xml-maven-plugin.version>1.0.2xml-maven-plugin.version>
    <xmlunit2.version>2.6.3xmlunit2.version>
  properties>

特别特别多的坐标，原来SpringBoot就在这里帮助我们来管理版本，所以说这个是版本仲裁中心也不为过了。后期如果你想要使用某个jar的其他版本可以在这里进行管理.