spring boot — day2 configuration

Focus on how to set up config from application.properties/*.properties

Using: @Component, @ConfigurationProperties, @PropertySource

1. get data from application.properties

• add config in application.properties

string1=withoutPrefix
int1=100

add a class for get config from properties

@Component
@ConfigurationProperties()
@Data //use Data with lombok, or your write setter and getter
public class ApplicationConfig {
    public String string1;
    public int int1;
}

in other class use @Resource d for spring boot bind data

@RestController
public class ConfigController {
    @Resource
    ApplicationConfig applicationConfig;
 

    @GetMapping("/config")
    public Object test() {
        System.out.println(applicationConfig.string1); 
        System.out.println(applicationConfig.int1);
        return "done";
    }

}

2. get data from application.properties with prefix

• add config in application.properties

xxx.string1=withoutPrefix
xxx.int1=100

add a class for get config from properties

@Component
@ConfigurationProperties(prefix = "xxx")
@Data
public class ApplicationConfigWithPrefix {
    public String string1;
    public int int1;
}

in other class also use @Resource

@RestController
public class ConfigController {
    @Resource
    ApplicationConfigWithPrefix applicationConfigWithPrefix;
 

    @GetMapping("/config")
    public Object test() {
        System.out.println(applicationConfigWithPrefix.string1); 
        System.out.println(applicationConfigWithPrefix.int1);
        return "done";
    }

}

3. get data from other .properties file

add other .properties file , ex :`other.properties` in resource

other.string1=other
other.int1=300

use PropertySource to set which file to get data

@Component
@PropertySource({"classpath:other.properties"})
@ConfigurationProperties(prefix = "other")
@Data
public class OtherConfig {
    public String string1;
    public int int1;
}
@RestController
public class ConfigController {
    @Resource
    OtherConfig otherConfig;
 

    @GetMapping("/config")
    public Object test() {
        System.out.println(otherConfig.string1); //other
        System.out.println(otherConfig.int1); //300
        return "done";
    }

}

4 setup data to create Bean

• create data class, ex: user

@Data
public class User {
    private String name1;
    private String password;
}

• set value in application.properties

user.name1=user123
user.password=password123

• create a configuration class

@Configuration
public class ConfigurationAutoBindData {
    @Bean
    @ConfigurationProperties(prefix = "user")
    public User user() {
        return new User();
    }
}

using:

@RestController
public class ConfigController {
    @Resource
    User user;
 

    @GetMapping("/config")
    public Object test() {
        System.out.println(user.getName1());
        System.out.println(user.getPassword());
        return "done";
    }

}

NOTE:

all config class need provide setter / getter, if only use `public` spring boot will not set data in class

git: https://github.com/cwnga2/spring_boot_study/tree/main/day2_configuration