What is the way to reference attribute variables in the springboot configuration file?

The attribute variable reference in the springboot configuration file@@

The application method of this attribute is field_name=@field_value@.

The two @ symbols are generated by springboot to replace the ${} attribute placeholder. The reason is that ${} will be processed by maven, so it should not be able to reference variables.

@@ method can refer to variables in springboot non-default configuration files (i.e. other configuration files);

springboot default configuration file is src/main/resources/application.properties

Usage of @@ and ${} in reference to attribute variables

Familiar environment-differentiated configuration methods

Configure spring directly in application.properties Just use the .profiles.active attribute to distinguish the environment.

@@what exactly is it?

${} and @@ are both ways springboot refers to attribute variables.

${} and @@

1) The use of ${}

The most commonly used one is to set the version number in the pom file The configuration usage, such as the following:

<properties>
	        <swagger.version>2.8.0</swagger.version>
	    </properties>
	    
		<dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger2</artifactId>
            <version>${swagger.version}</version>
        </dependency>

There is also the assignment operation in the configuration file or .sh file, such as the following:

IMAGES_NAME=brain-health-openplatform
CONTAINER_NAME=brain-health-openplatform
APP_PORT=7701
APP_HOME=/home/admin/brain-health-openplatform
#启动容器
docker run -d --name ${CONTAINER_NAME} -p ${APP_PORT}:${APP_PORT} -v ${APP_HOME}/logs:/logs ${CONTAINER_NAME}

2) The use of @@## The

#@@ method is often used to reference variables in springboot non-default configuration files (i.e. other configuration files). It is generated by springboot as an alternative attribute placeholder. The reason is that the {} attribute placeholder is generated. The reason is The attribute placeholder is generated because {} will be processed by maven, so it will not function as a reference variable when referencing a non-default configuration file.

For example, the yml in our project plays an overall role, injecting different values ​​through the configuration files of the four environments. I feel that the effect is the same as the original prod and test folders.

3) @@Introducing ordinary value values

In fact, my first question was not how to inject, but to see that all injections in the project have ownership relationships. , such as belonging to server/spring or mybatis or logging, etc. So I want to configure a common link path, how should I do it?

In fact, it is complicated. You only need to directly copy the key in the properties into the yml file, and it will automatically form a key-value pair.

# properties文件中：
customer.brain.training=XXX
brain.training.report=XXX
train.path.source=XXX

# yml文件中的注入
customer:
  brain:
    training: @customer.brain.training@
brain:
  training:
    report: @brain.training.report@
train:
  path:
    source: @train.path.source@

    // 项目中的使用，直接就是@value的正常形式
    @Value("${customer.brain.training}")
	private String CustomerBrainTrainingUrl;

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