Spring Boot三大特性

Spring Boot三大特性

• 组件自动装配：Web MVC、JDBC等

1. 激活自动装配：@EnableAutoConfiguration

@SpringBootApplication

在SpringBoot中的Application.java中的SpringBootApplication注解包括了如下注解：
@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}
)}
)

1. 配置：/META-INF/spring.factories

# AutoConfigureDataRedis auto-configuration imports
...

# Auto Configure
...

// MVC的自动配置
# AutoConfigureWebMvc auto-configuration imports
...

# AutoConfigureJdbc auto-configuration imports
org.springframework.boot.test.autoconfigure.jdbc.AutoConfigureJdbc=\
org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration,\
org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration

代理了相应的实现--各种配置

1. 实现：XXX(JDBC/MVC)AutoConfiguration

@Configuration(proxyBeanMethods = false)
@ConditionalOnWebApplication(type = Type.SERVLET)
@ConditionalOnClass({ Servlet.class, DispatcherServlet.class, WebMvcConfigurer.class })
@ConditionalOnMissingBean(WebMvcConfigurationSupport.class)
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE + 10)
@AutoConfigureAfter({ DispatcherServletAutoConfiguration.class, TaskExecutionAutoConfiguration.class,
		ValidationAutoConfiguration.class })
public class WebMvcAutoConfiguration {
...
}

具体实现

• 嵌入式Web容器：Tomcat、Jetty

• 生产准备特性：指标、健康检查、外部化配置等

1. 指标: /actuator/metrics
2. 健康检查：/actuator/health
3. 外部化配置：/actuator/configprops