• https://chat.openai.com/c/d75560a0-1c06-4195-80fc-563ec8449bc5
• https://www.baeldung.com/configuration-properties-in-spring-boot

---

Application properties

1. Register

Automatically registered files:

• application.property - default file
• application-.properties

Register custom properties-file

• use @propertySource / @propertySources
• keep here - src/main/resources : sb has utility method to read from resource folder.
• check : ReadConfigFromGlobalProperty.javaReadConfigFromGlobalProperty.java
• can have env/profile specific files too, as shoen below.

  @Configuration  
  @PropertySources(value = {
          @PropertySource(value = "classpath:global-database-${spring.profiles.active}.properties"),
          @PropertySource(value = "classpath:global-rabbit-mq-${spring.profiles.active}.properties")
  })
  

• external property files

  1. JVM ARG :: java -jar my-app.jar --spring.config.location=<path>/application.properties
  2. env var :: export SPRING_CONFIG_LOCATION=/config/external/application.properties
  3. Command Line Arguments  :: ?
  

2. Binding into custome class

• check : ConfigurationPropertiesByPrefixBean.java
• property --> sb does binding bts --> into Object (of ConfigurationPropertiesByPrefixBean class)
• @ConfigurationProperties

  @ConfigurationProperties(prefix = "mail")
  @ConfigurationPropertiesScan // register bean
  public class ConfigurationPropertiesByPrefixBean
  {
      ...
  }
  

  // Using @ConfigurationProperties on a @Bean Method
  // pending...
  

• more ways to register above class as bean - ConfigurationPropertiesByPrefixBean
• EnableConfigurationProperties({c1.class, c2.class}) --> enable/register explicitly, may be in Application.java file
• add @ConfigurationPropertiesScan Apply on class c1/c2 (done above)
• add @Component
• add @Configuration

in-built binding

• property name must match - b/w prop and java class fields.

  all these works
  - mail.hostName
  - mail.hostname
  - mail.host_name
  - mail.host-name
  - mail.HOST_NAME
  

  # prefix = mail
  
  # ------ String  --------
  mail.hostname =    mailer@mail.com
  
  # ------ number  --------
  mail.port     =    9000
  
  # ------ List / set --------
  mail.defaultRecipients[0]=admin@mail.com
  mail.defaultRecipients[1]=owner@mail.com
  
  # ------- Object  -------
  mail.credentials1.username=john
  mail.credentials1.password=password
  mail.credentials1.authMethod=SHA1
  
  # ------- Map<String,String>  ---------
  mail.additionalHeaders.redelivery=true
  mail.additionalHeaders.secure=true
  
  # ------- Map<String,Object>  ---------
  mail.map1.credentials1.username=mani
  mail.map1.credentials1.password=password1
  mail.map1.credentials2.username=lek
  mail.map1.credentials2.password=password12
  
  map :
  credentials1=object:{mani,password1}
  credentials2=object:{lek,password2}
  
  # ------- Map<String,list<Object>>  ---------
  
  # ----- Duration,DataSize ------
  

• check this for more Map binding example:
• Prop2Map.java

custom binding

• create converter class:
• 1 annotate with @ConfigurationPropertiesBinding
• 2 implement Converter --> @override TargetType convert(SourceType)
  • Prop2Map.javaCustomConverter_1.java
  • string to Credential binding
  • mail.credentials2 = john2,password2
• 3 add validation (JSR-380 format), if needed

  @NotBlank
  @length(min,max)
  @Max(1025)
  @Min(1025)
  @Pattern(regexp = "^[a-z0-9._%+-]+@[a-z0-9.-]+\\.[a-z]{2,6}$")
  

3. Read properties

• @Autowired Environmnet env.
• @value
• hardcode static value
• SpEL