In the development of using SpringBoot, some configuration parameters need to be defined in the yml file, and then introduced through Java classes

Spring boot provides some annotations to implement this function

• ConfigurationProperties
• Value
• EnableConfigurationProperties

The following provides examples to show how to introduce general variables, arrays, lists, m ap s, and reference objects.

[related code G itHub]

Introducing pom

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter</artifactId>
</dependency>

<dependency>
     <groupId>org.springframework.boot</groupId>
     <artifactId>spring-boot-configuration-processor</artifactId>
      <optional>true</optional>
</dependency>

<!--lombok Plug in, not required -->
<dependency> 
　　　<groupId>org.projectlombok</groupId> 
　　　<artifactId>lombok</artifactId> 
　　　<optional>true</optional> 
</dependency>

Annotation

A global annotation class is defined here,

@Data
@ToString
@ConfigurationProperties(prefix = "all")
public class AllConfigurationProperties {

    //Ordinary variable
    private  String name;
　　 //Reference object
    private  OtherProperties other;
    //array
    private  String[] server;
   //list
    private List list;
    //map
    private Map map;
   //Complex map
    private Map<String, ModuleConfig> modules = new LinkedHashMap();
   //Complex list
    private List<ModuleConfig> modulesList;

}

ConfigurationProperties: the specifier is a configuration class, which requires prefix configuration in yml.

What should be paid attention to
1. The name in the configuration class should conform to the naming method of Java Bean
2. The name in the configuration class should be the same as that in yml, otherwise @ Value should be used to specify
For example:

yml Document:

all:
　　name: libai
------------------------------------

＠Ｖalue("${all.name}")
private String myName;

3. If @ Value mode has been used, Setter method is not needed. Otherwise, the Setter method must be written for this variable. Here, use the annotation @ Data of lombok to configure. The Setter, getter and toString methods will be generated automatically

Reference object of the above configuration class

@Data
public class ModuleConfig {
    private static final long serialVersionUID = 5508512956753757169L;
    private String name;
    private String version;
    private String owner;
}

@Data
public class OtherProperties {

    private  Long id;
    private String version;
}

Enable configuration class

@Slf4j
@EnableConfigurationProperties(AllConfigurationProperties.class)
@Configuration
public class AutoConfiguration {

    @Autowired
    AllConfigurationProperties properties;

    @PostConstruct
    public void  init(){

        System.out.println("properties = " + properties);

    }

}

Use the @ EnableConfigurationProperties enable configuration class here. It will inject configuration parameters in yml for AllConfigurationProperties and create a bean, which can be used later by @ Autowired injection

@Configuration indicates that this is a Spring b oot configuration class

Use the init() method to output the configuration

Configuration in yml

all:
  name: libai
  other:
    id: 100
    version: 1.0.1

  server:
    - 127.0.0.1
    - 127.0.0.2
    - 127.0.0.3

  list:
    - 111
    - 222
    - 333

  map:
    key1: value1
    key2: value2
    key3: value3

  modules:
    key1:
      name: modules-name-1
      version: modules-version-1
      owner: modules-owner-1
    key2:
      name: modules-name-2
      version: modules-version-2
      owner: modules-owner-2

  modulesList:
    - name: modules-name-3
      version: modules-version-3
      owner: modules-owner-3
    - name: modules-name-4
      version: modules-version-4
      owner: modules-owner-4

output

properties =
 AllConfigurationProperties(
 name=libai, 
 other=OtherProperties(id=100, version=1.0.1),
 server=[127.0.0.1, 127.0.0.2, 127.0.0.3], 
 list=[111, 222, 333],
 map={
　　　key1=value1,
　　　 key2=value2, 
　　　key3=value3
　　　}, 
 modules={
　　　key1=ModuleConfig(name=modules-name-1, version=modules-version-1, owner=modules-owner-1),
　　 key2=ModuleConfig(name=modules-name-2, version=modules-version-2, owner=modules-owner-2)
　　　}, 
 modulesList=[
　　　ModuleConfig(name=modules-name-3, version=modules-version-3, owner=modules-owner-3), 
　　　ModuleConfig(name=modules-name-4, version=modules-version-4, owner=modules-owner-4)
　　　])