Spring Boot中Starter是什么

比如我们要在Spring Boot中引入Web MVC的支持时，我们通常会引入这个模块spring-boot-starter-web，而这个模块如果解压包出来会发现里面什么都没有，只定义了一些POM依赖。

经过研究，Starter主要用来简化依赖用的。比如我们之前做MVC时要引入日志组件，那么需要去找到log4j的版本，然后引入，现在有了Starter之后，直接用这个之后，log4j就自动引入了，也不用关心版本这些问题。

部分starters的依赖：

Starter(Group ID: org.springframework.boot)	传递依赖于
spring-boot-starter-log4j2	■ org.apache.logging.log4j:log4j-slf4j-impl ■ org.apache.logging.log4j:log4j-api ■ org.apache.logging.log4j:log4j-core ■ org.slf4j:jcl-over-slf4j ■ org.slf4j:jul-to-slf4j
spring-boot-starter-logging	■ ch.qos.logback:logback-classic ■ org.slf4j:jcl-over-slf4j ■ org.slf4j:jul-to-slf4j ■ org.slf4j:log4j-over-slf4j
spring-boot-starter-mail	■ org.springframework.boot:spring-boot-starter ■ org.springframework:spring-context ■ org.springframework:spring-context-support ■ com.sun.mail:javax.mail
spring-boot-starter-mobile	■ org.springframework.boot:spring-boot-starter ■ org.springframework.boot:spring-boot-starter-web ■ org.springframework.mobile:spring-mobile-device
spring-boot-starter-mustache	■ org.springframework.boot:spring-boot-starter ■ org.springframework.boot:spring-boot-starter-web ■ com.samskivert:jmustache
spring-boot-starter-redis	■ org.springframework.boot:spring-boot-starter ■ org.springframework.data:spring-data-redis ■ redis.clients:jedis
spring-boot-starter-remote-shell	■ org.springframework.boot:spring-boot-starter ■ org.springframework.boot:spring-boot-starter-actuator ■ org.crashub:crash.cli ■ org.crashub:crash.connectors.ssh (excludes org.codehaus.groovy:groovy-all) ■ org.crashub:crash.connectors.telnet (excludes javax.servlet:servlet-api, log4j :log4j, commons-logging:commons-logging) ■ org.crashub:crash.embed.spring(excludes org.springframework:spring-web, org.codehaus.groovy:groovy-all) ■ org.crashub:crash.plugins.cron (excludes org.codehaus.groovy:groovy-all) ■ org.crashub:crash.plugins.mail (excludes org.codehaus.groovy:groovy-all) ■ org.crashub:crash.shell (excludes org.codehaus.groovy:groovy-all) ■ org.codehaus.groovy:groovy
spring-boot-starter-security	■ org.springframework.boot:spring-boot-starter ■ org.springframework:spring-aop ■org.springframework.security:spring-security-config ■org.springframework.security:spring-security-web
spring-boot-starter-social-facebook	■org.springframework.boot:spring-boot-starter ■ org.springframework.boot:spring-boot-starter-web ■org.springframework.social:spring-social-config ■ org.springframework.social:spring-social-core ■ org.springframework.social:spring-social-web ■org.springframework.social:spring-social-facebook
spring-boot-starter-social-linkedin	■org.springframework.boot:spring-boot-starter ■ org.springframework.boot:spring-boot-starter-web ■org.springframework.social:spring-social-config ■ org.springframework.social:spring-social-core ■ org.springframework.social:spring-social-web ■org.springframework.social:spring-social-linkedin
spring-boot-starter-social-twitter	■org.springframework.boot:spring-boot-starter ■ org.springframework.boot:spring-boot-starter-web ■ org.springframework.social:spring-social-config ■ org.springframework.social:spring-social-core ■org.springframework.social:spring-social-web ■ org.springframework.social:spring-social-twitter
spring-boot-starter-test	■ junit:junit ■ org.mockito:mockito-core ■ org.hamcrest:hamcrest-core ■ org.hamcrest:hamcrest-library ■ org.springframework:spring-core(excludes commons-logging:commons-logging) ■ org.springframework:spring-test
spring-boot-starter-thymeleaf	■ org.springframework.boot:spring-boot-starter ■ org.springframework.boot:spring-boot-starter-web ■ org.thymeleaf:thymeleaf-spring4 ■nz.net.ultraq.thymeleaf:thymeleaf-layout-dialect
spring-boot-starter-tomcat	■ org.apache.tomcat.embed:tomcat-embed-core ■ org.apache.tomcat.embed:tomcat-embed-el ■org.apache.tomcat.embed:tomcat-embed-logging-juli ■org.apache.tomcat.embed:tomcat-embed-websocket
spring-boot-starter-undertow	■ io.undertow:undertow-core ■ io.undertow:undertow-servlet(excludes org.jboss.spec.javax.servlet:jboss-servlet-api_3.1_spec) ■ io.undertow:undertow-websockets-jsr ■ javax.servlet:javax.servlet-api ■ org.glassfish:javax.el
spring-boot-starter-validation	■ org.springframework.boot:spring-boot-starter ■ org.apache.tomcat.embed:tomcat-embed-el ■org.hibernate:hibernate-validator
spring-boot-starter-velocity	■ org.springframework.boot:spring-boot-starter ■ org.springframework.boot:spring-boot-starter-web ■ commons-beanutils:commons-beanutils ■ commons-collections:commons-collections ■ commons-digester:commons-digester ■ org.apache.velocity:velocity ■ org.apache.velocity:velocity-tools ■ org.springframework:spring-context-support
spring-boot-starter-web	■ org.springframework.boot:spring-boot-starter ■ org.springframework.boot:spring-boot-starter-tomcat ■ org.springframework.boot:spring-boot-starter-validation ■com.fasterxml.jackson.core:jackson-databind ■ org.springframework:spring-web ■ org.springframework:spring-webmvc
spring-boot-starter-websocket	■ org.springframework.boot:spring-boot-starter ■ org.springframework.boot:spring-boot-starter-web ■ org.springframework:spring-messaging ■org.springframework:spring-websocket
spring-boot-starter-ws	■ org.springframework.boot:spring-boot-starter ■ org.springframework.boot:spring-boot-starter-web ■org.springframework:spring-jms ■ org.springframework:spring-oxm ■ org.springframework.ws:spring-ws-core ■ org.springframework.ws:spring-ws-support

参考：

https://segmentfault.com/a/1190000004319673?_ea=568367

http://www.cnblogs.com/cz-xjw/p/6632402.html

http://blog.csdn.net/chszs/article/details/50610474

http://blog.csdn.net/flygoa/article/details/68484439

http://www.jianshu.com/p/85460c1d835a

http://www.jianshu.com/p/3754c0a5de90