What is Spring Boot? What are its advantages?

Spring Boot is a rapid development framework based on the Spring framework, which aims to simplify the development process and deployment process of Spring applications. Spring Boot provides automated configuration and a convention-over-configuration approach, allowing developers to focus on business logic without paying too much attention to the underlying technical details.

The advantages of Spring Boot are as follows:

1. Rapid development: Spring Boot provides automated configuration and a way of convention greater than configuration, which can quickly and easily create a Spring application. Developers can focus on business logic development without paying attention to the underlying technical implementation.

2. Simplified configuration: Spring Boot's automated configuration function eliminates the need for developers to write a large number of XML configuration files.

3. Excellent compatibility: Spring Boot is well compatible with existing Spring applications without the need for reconstruction.

4. Microservice capabilities: Spring Boot provides various dependency libraries and components that can be used to quickly build microservice applications.

5. Intelligent management: Spring Boot applications provide various operation and maintenance and monitoring functions, which can help developers better manage applications.

6. Strong scalability: Spring Boot is based on Spring and naturally supports expansion and enhancement.

In short, the Spring Boot framework greatly simplifies the development process of Spring applications, helps developers quickly create reliable applications, and provides a rich set of components and dependency libraries, providing developers with a more convenient and faster development experience.

How does Spring Boot automatically configure?

Spring Boot automatic configuration is implemented through Spring Boot's conditional configuration mechanism. Spring Boot's conditional configuration mechanism can determine whether a certain feature needs to be automatically configured based on the current application's environment, classpath, and other conditions.

Automatic configuration can be roughly divided into the following three steps:

Spring Boot will scan all Jar packages under the classpath and check the META-INF/spring.factories configuration file.
Spring Boot will automatically assemble Spring components based on the configuration declared in the spring.factories file.
During the automatic assembly process, Spring Boot will determine whether automatic configuration is required based on whether the corresponding bean already exists in the current application.

In order to accurately control the automatic configuration process, Spring Boot introduces a conditional configuration mechanism, which can automatically configure based on different conditions. The following are several classic conditional configuration examples:

@ConditionalOnClass: When a specific class exists in ClassPath, the corresponding Bean will be automatically configured.
@ConditionalOnBean: When a bean exists, the corresponding bean will be automatically configured.
@ConditionalOnProperty: When a specific property is set, the corresponding Bean will be automatically configured.
@ConditionalOnMissingBean: When a bean does not exist, the corresponding bean will be automatically configured.

These conditional configuration mechanisms allow Spring Boot to dynamically choose whether to automatically configure a certain function and how to implement a certain function based on the specific conditions of the current application environment.

In short, Spring Boot's automatic configuration mechanism uses convention over configuration, which can greatly reduce developers' workload and thus greatly improve development efficiency.