如何優化SpringBoot的項目的啟動速度

日常開發SpringBoot項目啟動類都用@SpringBootApplication，實際上它是下面三個注解的組合：

• @EnableAutoConfiguration: enable Spring Boot’s auto-configuration mechanism
• @ComponentScan: enable @Component scan on the package where the application is located (see the best practices)
• @Configuration: allow to register extra beans in the context or import additional configuration classes

啟動慢往往跟 @ComponentScan和 @EnableAutoConfiguration加載的內容太多有關，一種方法是不用這兩個注解，通過@import注解精確指定要加載掃描的類，但要加載的類多時又很麻煩，

可以用@SpringBootApplication注解下面的屬性：

• exclude: Exclude the list of classes from the auto configuration.
• excludeNames: Exclude the list of fully qualified class names from the auto configuration. This parameter added since spring boot 1.3.0.
• scanBasePackageClasses: Provide the list of classes that has to be applied for the @ComponentScan.
• scanBasePackages Provide the list of packages that has to be applied for the @ComponentScan. This parameter added since spring boot 1.3.0.

另外，如果SpringBoot項目啟動很慢， 可能 意味着你要重新拆分微服務。