sprint boot

1.起步依赖.
  查看：  mvn dependency:tree
  例如：

[INFO] +- org.springframework.boot:spring-boot-starter-data-jpa:jar:2.1.4.RELEASE:compile
[INFO] |  +- org.springframework.boot:spring-boot-starter-aop:jar:2.1.4.RELEASE:compile
[INFO] |  |  \- org.aspectj:aspectjweaver:jar:1.9.2:compile
[INFO] |  +- javax.transaction:javax.transaction-api:jar:1.3:compile
[INFO] |  +- javax.xml.bind:jaxb-api:jar:2.3.1:compile
[INFO] |  |  \- javax.activation:javax.activation-api:jar:1.2.0:compile
[INFO] |  +- org.hibernate:hibernate-core:jar:5.3.9.Final:compile
[INFO] |  |  +- javax.persistence:javax.persistence-api:jar:2.2:compile
[INFO] |  |  +- org.javassist:javassist:jar:3.23.1-GA:compile
[INFO] |  |  +- net.bytebuddy:byte-buddy:jar:1.9.12:compile
[INFO] |  |  +- antlr:antlr:jar:2.7.7:compile
[INFO] |  |  +- org.jboss:jandex:jar:2.0.5.Final:compile
[INFO] |  |  +- org.dom4j:dom4j:jar:2.1.1:compile
[INFO] |  |  \- org.hibernate.common:hibernate-commons-annotations:jar:5.0.4.Final:compile
[INFO] |  +- org.springframework.data:spring-data-jpa:jar:2.1.6.RELEASE:compile
[INFO] |  |  +- org.springframework.data:spring-data-commons:jar:2.1.6.RELEASE:compile
[INFO] |  |  +- org.springframework:spring-orm:jar:5.1.6.RELEASE:compile
[INFO] |  |  \- org.springframework:spring-tx:jar:5.1.6.RELEASE:compile
[INFO] |  \- org.springframework:spring-aspects:jar:5.1.6.RELEASE:compile

2.自动配置.
  查询classPath中的是否存在，如果有则创建并配置：
  @ConditionalOnBean .... others.