How to create and manage customized configuration information

How to embed system configuration information in an application

We know  Spring Boot  A lot of default configuration information is built in through the automatic configuration mechanism , And in this configuration information , Some of the system configuration information can also be applied to our application as configuration items .

for example , If you want to get the name of the current application and manage it as a configuration item , So it's very simple , We go straight through  ${spring.application.name}  A place holder can do this , As shown below ：

myapplication.name : ${spring.application.name}


adopt  ${}  Placeholders can also refer to other configuration items in the configuration file , For example, in the following configuration items , Final “system.description” The value of the configuration item is “The system springcss is used for health”.

system.name=springcss

system.domain=health

system.description=The system ${name} is used for ${domain}.


Let's look at another scene , Suppose we use  Maven  To build applications , Then you can dynamically obtain the information related to the system construction process according to the configuration items as shown below ：

info: 

 app:

 encoding: @[email protected]

 java:

 source: @[email protected]

 target: @[email protected]


The above configuration has the same effect as the static configuration shown below ：

info:

 app:

 encoding: UTF-8

 java:

 source: 1.8.0_31

 target: 1.8.0_31


According to different needs , It's useful to embed system configuration information in an application , Especially in some areas  DevOps  In the application scenario of .

How to create and use custom configuration information

In the real development process , In the face of complex application scenarios ,Spring Boot  The built-in configuration information provided may not fully meet the development requirements , This requires developers to create and manage various customized configuration information . for example , For an e-commerce application scenario , In order to encourage users to complete the order operation , We hope to give users a certain number of points for each order we complete . In terms of system scalability , This integral should be adjustable , So we created a custom configuration item , As shown below ：

springcss.order.point = 10


here , We set the score of each order as  10, How can the application get the content of this configuration item ？ There are usually two ways .

Use  @Value  annotation

Use  @Value  Annotation is a traditional way to inject configuration item content . For the custom configuration items given above , We can build a  SpringCssConfig  class , As shown below ：

@Component

public class SpringCssConfig {
 @Value("${springcss.order.point}")

 private int point;
}


stay  SpringCssConfig  Class , All we have to do is add... To the field  @Value  annotation , And point to the name of the configuration item .

Use  @ConfigurationProperties  annotation

Comparison  @Value  annotation , A more modern approach is to use  @ConfigurationProperties  annotation . When using this annotation , We usually set one “prefix” Property to specify the prefix of the configuration item , As shown below ：

@Component

@ConfigurationProperties(prefix = "springcss.order")

public class SpringCsshConfig {

 

 private int point;

 

 // Omit  getter/setter

}


comparison  @Value  Annotations can only be used to specify a specific configuration item ,@ConfigurationProperties  It can be used to extract configuration content in batch . Just specify  prefix, We can put the  prefix  All configuration items under are automatically injected into the business code by name .

Let's consider a more common and complex scenario ： Suppose that the points obtained by the user according to the order operation are not fixed , But according to each different type of order, there will be different points , Now the content of the configuration item , If you use  Yaml  The format should be like this ：

springcss:

 points:

 orderType[1]: 10

 orderType[2]: 20

 orderType[3]: 30


If you want to load all these configuration items into the business code , Use  @ConfigurationProperties  Annotations are also easy to implement . We can configure the class directly  SpringCssConfig  Define a  Map  object , And then through  Key-Value  Yes, to save the configuration data , As shown below ：

@Component

@ConfigurationProperties(prefix="springcss.points")

public class SpringCssConfig {

 

 private Map<String, Integer> orderType = new HashMap<>();



 // Omit  getter/setter

}


You can see here by creating a  HashMap  To save these  Key-Value  Yes . Allied , We can also implement the automatic embedding of some common data structures .