前面我們編寫了一個springboot,通過這個helloworld我們發(fā)現(xiàn),Springboot確實簡單,他只需要寫一個主程序,來啟動Springboot的應(yīng)用,接下來我們就按照我們的業(yè)務(wù)邏輯,編寫一些Controller,service,我們根本不需要做任何配置,那為什么會有這么神奇的一個現(xiàn)象呢,我們從pom文件來分析一下,我們先來說他的pom文件,在這個pom文件里面呢,就是導(dǎo)入了相關(guān)依賴,這些依賴導(dǎo)入了這么多jar包,首先這里有一個parent,<parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>1.5.12.RELEASE</version><relativePath/> </parent>我們導(dǎo)入了一個父項目,boot-starter-parent,Sprintboot所有starter的父項目,父項目有什么用呢,我們依賴是用來做依賴管理,那我們來看一下我們的父項目,我們發(fā)現(xiàn)這個父項目他還依賴一個父項目,<parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-dependencies</artifactId><version>1.5.12.RELEASE</version><relativePath>../../spring-boot-dependencies</relativePath> </parent>那么這有什么用呢,再來點進(jìn)去看一下,這里有一個properties,屬性里面有一個Dependency versions,定義了每一個依賴的版本,比如activemq的依賴,包括做切面的aspect的版本號,commons的依賴,都為我們做了依賴管理<properties><!-- Dependency versions --><activemq.version>5.14.5</activemq.version><antlr2.version>2.7.7</antlr2.version><appengine-sdk.version>1.9.63</appengine-sdk.version><artemis.version>1.5.6</artemis.version><aspectj.version>1.8.13</aspectj.version><assertj.version>2.6.0</assertj.version><atomikos.version>3.9.3</atomikos.version><bitronix.version>2.1.4</bitronix.version><caffeine.version>2.3.5</caffeine.version><cassandra-driver.version>3.1.4</cassandra-driver.version><classmate.version>1.3.4</classmate.version><commons-beanutils.version>1.9.3</commons-beanutils.version><commons-collections.version>3.2.2</commons-collections.version><commons-codec.version>1.10</commons-codec.version><commons-dbcp.version>1.4</commons-dbcp.version><commons-dbcp2.version>2.1.1</commons-dbcp2.version><commons-digester.version>2.1</commons-digester.version><commons-pool.version>1.6</commons-pool.version><commons-pool2.version>2.4.3</commons-pool2.version><couchbase-client.version>2.3.7</couchbase-client.version><couchbase-cache-client.version>2.1.0</couchbase-cache-client.version><crashub.version>1.3.2</crashub.version><derby.version>10.13.1.1</derby.version><dom4j.version>1.6.1</dom4j.version><dropwizard-metrics.version>3.1.5</dropwizard-metrics.version><ehcache.version>2.10.4</ehcache.version><ehcache3.version>3.2.3</ehcache3.version><embedded-mongo.version>1.50.5</embedded-mongo.version><flyway.version>3.2.1</flyway.version><freemarker.version>2.3.28</freemarker.version><elasticsearch.version>2.4.6</elasticsearch.version><gemfire.version>8.2.9</gemfire.version><glassfish-el.version>3.0.0</glassfish-el.version><gradle.version>2.9</gradle.version><groovy.version>2.4.15</groovy.version><gson.version>2.8.2</gson.version><h2.version>1.4.197</h2.version><hamcrest.version>1.3</hamcrest.version><hazelcast.version>3.7.8</hazelcast.version><hazelcast-hibernate4.version>3.7.1</hazelcast-hibernate4.version><hazelcast-hibernate5.version>1.1.3</hazelcast-hibernate5.version><hibernate.version>5.0.12.Final</hibernate.version><hibernate-validator.version>5.3.6.Final</hibernate-validator.version><hikaricp.version>2.5.1</hikaricp.version><hikaricp-java6.version>2.3.13</hikaricp-java6.version><hikaricp-java7.version>2.4.13</hikaricp-java7.version><hsqldb.version>2.3.5</hsqldb.version><htmlunit.version>2.21</htmlunit.version><httpasyncclient.version>4.1.3</httpasyncclient.version><httpclient.version>4.5.5</httpclient.version><httpcore.version>4.4.9</httpcore.version><infinispan.version>8.2.10.Final</infinispan.version><jackson.version>2.8.11.20180217</jackson.version><janino.version>2.7.8</janino.version><javassist.version>3.21.0-GA</javassist.version> <!-- Same as Hibernate --><javax-cache.version>1.0.0</javax-cache.version><javax-mail.version>1.5.6</javax-mail.version><javax-transaction.version>1.2</javax-transaction.version><javax-validation.version>1.1.0.Final</javax-validation.version><jaxen.version>1.1.6</jaxen.version><jaybird.version>2.2.14</jaybird.version><jboss-logging.version>3.3.2.Final</jboss-logging.version><jboss-transaction-spi.version>7.6.0.Final</jboss-transaction-spi.version><jdom2.version>2.0.6</jdom2.version><jedis.version>2.9.0</jedis.version><jersey.version>2.25.1</jersey.version><jest.version>2.0.4</jest.version><jetty.version>9.4.9.v20180320</jetty.version><jetty-jsp.version>2.2.0.v201112011158</jetty-jsp.version><jetty-el.version>8.0.33</jetty-el.version><jms-api.version>1.1-rev-1</jms-api.version><jmustache.version>1.13</jmustache.version><jna.version>4.2.2</jna.version><joda-time.version>2.9.9</joda-time.version><jolokia.version>1.3.7</jolokia.version><jooq.version>3.9.6</jooq.version><json.version>20140107</json.version><jsonassert.version>1.4.0</jsonassert.version><json-path.version>2.2.0</json-path.version><jstl.version>1.2</jstl.version><jtds.version>1.3.1</jtds.version><junit.version>4.12</junit.version><liquibase.version>3.5.5</liquibase.version><log4j2.version>2.7</log4j2.version><logback.version>1.1.11</logback.version><lombok.version>1.16.20</lombok.version><mariadb.version>1.5.9</mariadb.version><mssql-jdbc.version>6.1.0.jre7</mssql-jdbc.version><mockito.version>1.10.19</mockito.version><mongodb.version>3.4.3</mongodb.version><mysql.version>5.1.46</mysql.version><narayana.version>5.5.31.Final</narayana.version><nekohtml.version>1.9.22</nekohtml.version><neo4j-ogm.version>2.1.6</neo4j-ogm.version><postgresql.version>9.4.1212.jre7</postgresql.version><querydsl.version>4.1.4</querydsl.version><reactor.version>2.0.8.RELEASE</reactor.version><reactor-spring.version>2.0.7.RELEASE</reactor-spring.version><selenium.version>2.53.1</selenium.version><selenium-htmlunit.version>2.21</selenium-htmlunit.version><sendgrid.version>2.2.2</sendgrid.version><servlet-api.version>3.1.0</servlet-api.version><simple-json.version>1.1.1</simple-json.version><slf4j.version>1.7.25</slf4j.version><snakeyaml.version>1.17</snakeyaml.version><solr.version>5.5.5</solr.version><spock.version>1.0-groovy-2.4</spock.version><spring.version>4.3.16.RELEASE</spring.version><spring-amqp.version>1.7.7.RELEASE</spring-amqp.version><spring-cloud-connectors.version>1.2.5.RELEASE</spring-cloud-connectors.version><spring-batch.version>3.0.9.RELEASE</spring-batch.version><spring-data-releasetrain.version>Ingalls-SR11</spring-data-releasetrain.version><spring-hateoas.version>0.23.0.RELEASE</spring-hateoas.version><spring-integration.version>4.3.15.RELEASE</spring-integration.version><spring-integration-java-dsl.version>1.2.3.RELEASE</spring-integration-java-dsl.version><spring-kafka.version>1.1.8.RELEASE</spring-kafka.version><spring-ldap.version>2.3.2.RELEASE</spring-ldap.version><spring-loaded.version>1.2.8.RELEASE</spring-loaded.version><spring-mobile.version>1.1.5.RELEASE</spring-mobile.version><spring-plugin.version>1.2.0.RELEASE</spring-plugin.version><spring-restdocs.version>1.1.3.RELEASE</spring-restdocs.version><spring-retry.version>1.2.2.RELEASE</spring-retry.version><spring-security.version>4.2.5.RELEASE</spring-security.version><spring-security-jwt.version>1.0.9.RELEASE</spring-security-jwt.version><spring-security-oauth.version>2.0.14.RELEASE</spring-security-oauth.version><spring-session.version>1.3.2.RELEASE</spring-session.version><spring-social.version>1.1.6.RELEASE</spring-social.version><spring-social-facebook.version>2.0.3.RELEASE</spring-social-facebook.version><spring-social-linkedin.version>1.0.2.RELEASE</spring-social-linkedin.version><spring-social-twitter.version>1.1.2.RELEASE</spring-social-twitter.version><spring-ws.version>2.4.2.RELEASE</spring-ws.version><sqlite-jdbc.version>3.15.1</sqlite-jdbc.version><statsd-client.version>3.1.0</statsd-client.version><sun-mail.version>${javax-mail.version}</sun-mail.version><thymeleaf.version>2.1.6.RELEASE</thymeleaf.version><thymeleaf-extras-springsecurity4.version>2.1.3.RELEASE</thymeleaf-extras-springsecurity4.version><thymeleaf-extras-conditionalcomments.version>2.1.2.RELEASE</thymeleaf-extras-conditionalcomments.version><thymeleaf-layout-dialect.version>1.4.0</thymeleaf-layout-dialect.version><thymeleaf-extras-data-attribute.version>1.3</thymeleaf-extras-data-attribute.version><thymeleaf-extras-java8time.version>2.1.0.RELEASE</thymeleaf-extras-java8time.version><tomcat.version>8.5.29</tomcat.version><undertow.version>1.4.23.Final</undertow.version><unboundid-ldapsdk.version>3.2.1</unboundid-ldapsdk.version><webjars-hal-browser.version>9f96c74</webjars-hal-browser.version><webjars-locator.version>0.32-1</webjars-locator.version><wsdl4j.version>1.6.3</wsdl4j.version><xml-apis.version>1.4.01</xml-apis.version><!-- Plugin versions --><build-helper-maven-plugin.version>1.10</build-helper-maven-plugin.version><exec-maven-plugin.version>1.5.0</exec-maven-plugin.version><git-commit-id-plugin.version>2.2.3</git-commit-id-plugin.version><maven-antrun-plugin.version>1.8</maven-antrun-plugin.version><maven-assembly-plugin.version>2.6</maven-assembly-plugin.version><maven-clean-plugin.version>2.6.1</maven-clean-plugin.version><maven-compiler-plugin.version>3.1</maven-compiler-plugin.version><maven-dependency-plugin.version>2.10</maven-dependency-plugin.version><maven-deploy-plugin.version>2.8.2</maven-deploy-plugin.version><maven-eclipse-plugin.version>2.10</maven-eclipse-plugin.version><maven-enforcer-plugin.version>1.4</maven-enforcer-plugin.version><maven-failsafe-plugin.version>2.18.1</maven-failsafe-plugin.version><maven-install-plugin.version>2.5.2</maven-install-plugin.version><maven-invoker-plugin.version>1.10</maven-invoker-plugin.version><maven-help-plugin.version>2.2</maven-help-plugin.version><maven-jar-plugin.version>2.6</maven-jar-plugin.version><maven-javadoc-plugin.version>2.10.4</maven-javadoc-plugin.version><maven-resources-plugin.version>2.7</maven-resources-plugin.version><maven-shade-plugin.version>2.4.3</maven-shade-plugin.version><maven-site-plugin.version>3.5.1</maven-site-plugin.version><maven-source-plugin.version>2.4</maven-source-plugin.version><maven-surefire-plugin.version>2.18.1</maven-surefire-plugin.version><maven-war-plugin.version>2.6</maven-war-plugin.version><versions-maven-plugin.version>2.2</versions-maven-plugin.version> </properties>它是來真正管理Spring Boot應(yīng)用里面的所有依賴版本,他來管理所有的這些依賴,也可以稱為Springboot的版本仲裁中心,有了他以后,以后導(dǎo)入我們依賴,默認(rèn)是不需要寫版本的,MYSQL驅(qū)動默認(rèn)是不需要寫版本的,所有的版本依賴都在dependecy里面,沒有在dependency管理的,我們自然要來寫版本,需要聲明版本號,這個是第一個版本仲裁 接下來我們來看第二個,父項目只是作為一個版本仲裁,那么jar包是有誰導(dǎo)進(jìn)來的呢,我們在我們的項目里邊,除了依賴這個父項目以外,這里還有一個stater-web,導(dǎo)入了一個依賴,<dependencies><dependency><!-- 引入web模塊 --><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency> </dependencies>我們導(dǎo)入了這個依賴,這個依賴也沒有寫版本號,因為SprintBoot幫我們自動仲裁,然后他的名叫做spring-boot-starter-web,我們把它拆成兩個詞,一個是sprint-boot-starter,一個是web,我為什么要這么拆呢,大家來看,以前的父項目叫做spring-boot-starter,的parent,Spring-boot-starter的父項目,而我們這里是spring-boot-starter的web,而什么叫做spring-boot-starter呢,我們稱為spring-boot的場景啟動器,那他的作用是什么,不妨進(jìn)入我們的spring-boot-starter-web,他這里有聲明一些依賴導(dǎo)入,他依賴spring-boot-starter基礎(chǔ)項目,也依賴spring-boot-starter-tomcat,<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-tomcat</artifactId><version>1.5.12.RELEASE</version> </dependency>還有hibernate-validator,<dependency><groupId>org.hibernate</groupId><artifactId>hibernate-validator</artifactId><version>${hibernate-validator.version}</version> </dependency>我們來做數(shù)據(jù)校驗的,只是jackson,<dependency><groupId>com.fasterxml.jackson</groupId><artifactId>jackson-bom</artifactId><version>${jackson.version}</version><scope>import</scope><type>pom</type> </dependency>springmvc兩個jar包<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-websocket</artifactId><version>1.5.12.RELEASE</version> </dependency>幫我們導(dǎo)入了web模塊正常運行所依賴的組件,場景啟動器當(dāng)我們使用web模塊的時候,他來幫我們導(dǎo)入相關(guān)的web模塊,依賴的版本通過父項目進(jìn)行仲裁,而在Springboot里面,還有更多的類似啟動器,我們可以參考springboot的官方文檔,https://docs.spring.io/spring-boot/docs/1.5.22.RELEASE/reference/html/using-boot-build-systems.html #using-boot-starter搜一下StartersStarters are a set of convenient dependency descriptors that you can include in your application.我們就會有相應(yīng)的依賴了,spring-boot將所有的功能,都抽取出來了一個個場景,比如我們要用activemq,那么就有activemq的啟動器,如果要用amqp高級消息隊列,就有這個啟動器,如果要做aop功能,我們就導(dǎo)入這個啟動器,比如我們要做數(shù)據(jù)jpa訪問,spring-boot-starter-activemqspring-boot-starter-amqpspring-boot-starter-aopspring-boot-starter-data-jpa如果左數(shù)據(jù)訪問的redis模塊,spring-boot-starter-data-redis導(dǎo)入這個,如果我們要進(jìn)行郵件開發(fā),我們就導(dǎo)入這個spring-boot-starter-mail如果我們要進(jìn)行web開發(fā),我們導(dǎo)入這個spring-boot-starter-webSprintboot將所有的功能場景,都抽取出來,然后做成一個個的starters,稱之為啟動器,我們只需要在項目里面,引入這些starter,相關(guān)場景的所有依賴,都會導(dǎo)入進(jìn)來,而且版本由springboot進(jìn)行自動控制,我們要用某一個功能,就導(dǎo)什么場景,我們就不交依賴了,就叫啟動器,有了他以后呢,我們每一種場景,sprintboot都幫我們考慮到,不需要導(dǎo)入這個啟動器,應(yīng)用就走起來了,你點過來就有pom文件來描述

比如我們來看郵件開發(fā)場景,他就會來描述,https://github.com/spring-projects/spring-boot/blob/v1.5.22.RELEASE/spring-boot-starters/ spring-boot-starter-mail/pom.xml<dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter</artifactId></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-context-support</artifactId></dependency><dependency><groupId>com.sun.mail</groupId><artifactId>javax.mail</artifactId></dependency> </dependencies>會導(dǎo)入spring-boot-starter,還會導(dǎo)Spring環(huán)境,還有環(huán)境支持,還有javax.mail做郵件開發(fā),大家都可以來參考文檔,springboot有多少種場景,全部都在這,未來就是圍繞著他來編寫 <?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starters</artifactId><version>1.5.22.RELEASE</version></parent><artifactId>spring-boot-starter-mail</artifactId><name>Spring Boot Mail Starter</name><description>Starter for using Java Mail and Spring Framework's email sendingsupport</description><url>https://projects.spring.io/spring-boot/</url><organization><name>Pivotal Software, Inc.</name><url>https://www.spring.io</url></organization><properties><main.basedir>${basedir}/../..</main.basedir></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter</artifactId></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-context-support</artifactId></dependency><dependency><groupId>com.sun.mail</groupId><artifactId>javax.mail</artifactId></dependency></dependencies> </project>

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