springboot项结构分析

三. SpringBoot 结构

3.1.SpringBoot 工作原理

Spring boot应用程序采用各种Starters启动器,入口类是包含@SpringBootApplication注解和main方法的类,然后使用@ComponentScan注解自动扫描项目中的所有组件,并且Spring Boot会根据@EnableAutoConfiguration注解将项目中的依赖项自动配置到应用程序中.例如,如果MySQL数据库在类路径上,但尚未配置任何数据库连接,则Spring Boot会自动配置内存数据库.

3.2 SpringBoot入口类

Spring Boot应用程序的入口点是包含@SpringBootApplication注解的类,该类中包含运行Spring Boot应用程序的main方法.默认一般是一个* application 结尾。

@SpringBootApplication注解包括自动配置,组件扫描和Spring Boot配置.
如果将@SpringBootApplication注解添加到类中,则无需添加@EnableAutoConfiguration,@ComponentScan和@SpringBootConfiguration注解.@SpringBootApplication注解包括其他所有的注解.

3.3 常见注解

1 @SpringBootApplication

@SpringBootApplication注解是Spring Boot的核心注解,用于标注程序是一个springboot 程序,它是一个组合注解,由多个注解组合而成

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(excludeFilters = {
   
		@Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
		@Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })
public @interface SpringBootApplication {
   
  //此处忽略接口内部内容
}

2 @SpringBootConfiguration注解

@SpringBootConfiguration注解可以用Java代码的形式实现spring中xml配置文件配置的效果。也就是用来加载配置文件。

@Target({
   ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Configuration
public @interface SpringBootConfiguration {
   
}

3 @EnableAutoConfiguration注解

启用自动配置，该注解会使Spring Boot根据项目中依赖的jar包自动配置项目的配置项,这也是 springboot 的核心注解之一,我们只需要将项目需要的依赖包导入进来,它会自动帮我们配置这个依赖需要的基本配置
比如我们的项目引入了spring-boot-starter-web依赖,springboot 会自动帮我们配置 tomcat 和 springmvc

4 @ComponentScan 注解

默认扫描@SpringBootApplication类所在包的同级目录以及它的子目录。用来扫描组件和自动装配。

springboot 支持的自动配置可以查看到

在spring-boot-autoconfigure包中包含了支持的自动装配依赖,截图只是其中一部分,我们开发中常见的依赖都做了基本配置

3.4 Springboot 全局配置文件

1.格式

​ SpringBoot使用的全局配置文件有两种格式：

​ • application.properties

​ • application.yml

​ 虽然后缀不一样，但是项目中有一个就可以了，yml格式比properties格式的简洁一些。

​ 这个文件的位置在配置文件放在src/main/resources目录或者类路径/config下。

  properties 和 .yml，它们的区别主要是书写格式不同。
    1).properties
      server.port=8088
      server.servlet.context-path=/testboot
    2).yml
    server:
      port: 8088
      servlet：
        context-path: /testboot
    另外yml 格式不支持 @PropertySource 注解导入配置 
    :和值之间有一个空格

2.作用

​ 全局配置文件的作用是：可以对一些默认配置值进行修改。

3.5 starter 启动器

springboot 提供了很多 starter, 可以帮我们快速构建相应的开发环境,导入相关的依赖,并设置相关配置

Name	Description	Pom
spring-boot-starter	Core starter, including auto-configuration support, logging and YAML 核心启动器,包括自动配置,日志以及 YAML 支持	Pom
spring-boot-starter-activemq	Starter for JMS messaging using Apache ActiveMQ 对Apache ActiveMQ提供支持	Pom
spring-boot-starter-amqp	Starter for using Spring AMQP and Rabbit MQ 对Spring AMQP 和 Rabbit MQ支持	Pom
spring-boot-starter-aop	Starter for aspect-oriented programming with Spring AOP and AspectJ 对 spring AOP和AspectJ提供支持	Pom
spring-boot-starter-artemis	Starter for JMS messaging using Apache Artemis 对Apache Artemis提供支持	Pom
spring-boot-starter-batch	Starter for using Spring Batch	Pom
spring-boot-starter-cache	Starter for using Spring Framework’s caching support	Pom
spring-boot-starter-cloud-connectors	Starter for using Spring Cloud Connectors which simplifies connecting to services in cloud platforms like Cloud Foundry and Heroku	Pom
spring-boot-starter-data-cassandra	Starter for using Cassandra distributed database and Spring Data Cassandra	Pom
spring-boot-starter-data-cassandra-reactive	Starter for using Cassandra distributed database and Spring Data Cassandra Reactive	Pom
spring-boot-starter-data-couchbase	Starter for using Couchbase document-oriented database and Spring Data Couchbase	Pom
spring-boot-starter-data-couchbase-reactive	Starter for using Couchbase document-oriented database and Spring Data Couchbase Reactive	Pom
spring-boot-starter-data-elasticsearch	Starter for using Elasticsearch search and analytics engine and Spring Data Elasticsearch	Pom
spring-boot-starter-data-jpa	Starter for using Spring Data JPA with Hibernate	Pom
spring-boot-starter-data-ldap	Starter for using Spring Data LDAP	Pom
spring-boot-starter-data-mongodb	Starter for using MongoDB document-oriented database and Spring Data MongoDB	Pom
spring-boot-starter-data-mongodb-reactive	Starter for using MongoDB document-oriented database and Spring Data MongoDB Reactive	Pom
spring-boot-starter-data-neo4j	Starter for using Neo4j graph database and Spring Data Neo4j	Pom
spring-boot-starter-data-redis	Starter for using Redis key-value data store with Spring Data Redis and the Lettuce client	Pom
spring-boot-starter-data-redis-reactive	Starter for using Redis key-value data store with Spring Data Redis reactive and the Lettuce client	Pom
spring-boot-starter-data-rest	Starter for exposing Spring Data repositories over REST using Spring Data REST	Pom
spring-boot-starter-data-solr	Starter for using the Apache Solr search platform with Spring Data Solr	Pom
spring-boot-starter-freemarker	Starter for building MVC web applications using FreeMarker views	Pom
spring-boot-starter-groovy-templates	Starter for building MVC web applications using Groovy Templates views	Pom
spring-boot-starter-hateoas	Starter for building hypermedia-based RESTful web application with Spring MVC and Spring HATEOAS	Pom
spring-boot-starter-integration	Starter for using Spring Integration	Pom
spring-boot-starter-jdbc	Starter for using JDBC with the Tomcat JDBC connection pool	Pom
spring-boot-starter-jersey	Starter for building RESTful web applications using JAX-RS and Jersey. An alternative to spring-boot-starter-web	Pom
spring-boot-starter-jooq	Starter for using jOOQ to access SQL databases. An alternative to spring-boot-starter-data-jpa or spring-boot-starter-jdbc	Pom
spring-boot-starter-json	Starter for reading and writing json	Pom
spring-boot-starter-jta-atomikos	Starter for JTA transactions using Atomikos	Pom
spring-boot-starter-jta-bitronix	Starter for JTA transactions using Bitronix	Pom
spring-boot-starter-jta-narayana	Spring Boot Narayana JTA Starter	Pom
spring-boot-starter-mail	Starter for using Java Mail and Spring Framework’s email sending support	Pom
spring-boot-starter-mustache	Starter for building web applications using Mustache views	Pom
spring-boot-starter-quartz	Spring Boot Quartz Starter	Pom
spring-boot-starter-security	Starter for using Spring Security	Pom
spring-boot-starter-test	Starter for testing Spring Boot applications with libraries including JUnit, Hamcrest and Mockito	Pom
spring-boot-starter-thymeleaf	Starter for building MVC web applications using Thymeleaf views	Pom
spring-boot-starter-validation	Starter for using Java Bean Validation with Hibernate Validator	Pom
spring-boot-starter-web	Starter for building web, including RESTful, applications using Spring MVC. Uses Tomcat as the default embedded container	Pom
spring-boot-starter-web-services	Starter for using Spring Web Services	Pom
spring-boot-starter-webflux	Starter for building WebFlux applications using Spring Framework’s Reactive Web support	Pom
spring-boot-starter-websocket	Starter for building WebSocket applications using Spring Framework’s WebSocket support	Pom

附录 springboot 全局配置属性

# ===================================================================
# COMMON SPRING BOOT PROPERTIES
#
# This sample file is provided as a guideline. Do NOT copy it in its
# entirety to your own application.               ^^^
# ===================================================================


# ----------------------------------------
# CORE PROPERTIES
# ----------------------------------------

# BANNER
banner.charset=UTF-8 # Banner file encoding.
banner.location=classpath:banner.txt # Banner file location.
banner.image.location=classpath:banner.gif # Banner image file location (jpg/png can also be used).
banner.image.width= # Width of the banner image in chars (default 76)
banner.image.height= # Height of the banner image in chars (default based on image height)
banner.image.margin= # Left hand image margin in chars (default 2)
banner.image.invert= # If images should be inverted for dark terminal themes (default false)

# LOGGING
logging.config= # Location of the logging configuration file. For instance `classpath:logback.xml` for Logback
logging.exception-conversion-word=%wEx # Conversion word used when logging exceptions.
logging.file= # Log file name. For instance `myapp.log`
logging.level.*= # Log levels severity mapping. For instance `logging.level.org.springframework=DEBUG`
logging.path= # Location of the log file. For instance `/var/log`
logging.pattern.console= # Appender pattern for output to the console. Only supported with the default logback setup.
logging.pattern.file= # Appender pattern for output to the file. Only supported with the default logback setup.
logging.pattern.level= # Appender pattern for log level (default %5p). Only supported with the default logback setup.
logging.register-shutdown-