1. The purpose of this post

I would demo three simple ways to read properties of spring boot configuration files..

2. Environments

  • springboot 1.x and 2.x
  • java 1.8+

3. Way 1: Read from application.properties by @Value annotation

Add these properties to your default configuration file: src/main/resources/application.properties

info.name=Mike
info.desc=Good boy

Use @Value like this:

package com.test.sb1jt.commands;

import com.test.sb1jt.config.InfoConfig;
import com.test.sb1jt.config.SysConfig;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;

@Component
public class MyCommand implements CommandLineRunner {
    private static Logger logger = LoggerFactory.getLogger(MyCommand.class);

    @Value("${info.name}") //1.Auto configure name property by reading info.name from application.properties
    private String name;

    @Value("${info.desc}") //2.Auto configure desc property by reading info.desc from application.properties
    private String desc;

    @Override
    public void run(String... strings) throws Exception {
        logger.info("MyCommand run");

        logger.info("name is {},desc is {}",name,desc); //3. print the name and desc
    }
}

Run the code ,we get this:

2019-05-23 12:45:58.827  INFO 31595 --- [           main] com.test.sb1jt.commands.MyCommand        : name is Mike,desc is Good boy

4. Way 2: Read from application.properties by @ConfigurationProperties annotation

Instead of @Value annotion, you can use @ConfigurationProperties,which can read some specific prefixed properties from your application.properties to your class properties.

Add these properties to your springboot application.properties

info.name=Mike
info.desc=Good boy

Add a class which use @ConfigurationProperties like this:

package com.test.sb1jt.config;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

@Component
@ConfigurationProperties(prefix = "info")
public class InfoConfig {
    private String name; // info.name mapped to this property
    private String desc; // info.desc mapped to this property

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getDesc() {
        return desc;
    }

    public void setDesc(String desc) {
        this.desc = desc;
    }
}

Then print properties like this:

package com.test.sb1jt.commands;

import com.test.sb1jt.config.InfoConfig;
import com.test.sb1jt.config.SysConfig;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;
import com.test.sb1jt.config.InfoConfig;

@Component
public class MyCommand implements CommandLineRunner {
    private static Logger logger = LoggerFactory.getLogger(MyCommand.class);

    @Autowired
    private InfoConfig infoConfig; 

    @Override
    public void run(String... strings) throws Exception {
        logger.info("MyCommand run");

        logger.info("infoconfig name is {},desc is {}",infoConfig.getName(),
                infoConfig.getDesc());
    }
}

Run the code ,we get this:

2019-05-23 12:45:58.827  INFO 31595 --- [           main] com.test.sb1jt.commands.MyCommand        : infoconfig name is Mike,desc is Good boy

5. Way 3: Read from your custom xxx.properties by @ProperySource annotation

By reading previous sections, you can see that by using @Value or @ConfigurationProperties, it’s easy to read properties in springboot’s default application.properties, but what should we do if we want read properties from a custom properties file?

According to this document,Spring provides @PropertySource annotation to read custom file properties.

Create a new file named sysconfig.properties in src/main/resources/ , add these properties to it:

sysname = BDS
sysdesc = Big data system

Create a new class to use the @PropertySource like this:

package com.test.sb1jt.config;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.PropertySource;
import org.springframework.stereotype.Component;

@Component
@PropertySource(value={"sysconfig.properties"}) //read from your custom src/main/resources/sysconfig.properties
public class SysConfig {
    @Value("${sysname}") // mapping from sysname to this property
    private String sysName;

    @Value("${sysdesc}") // mapping from sysdesc to this property
    private String sysDesc;

    public String getSysName() {
        return sysname;
    }

    public void setSysName(String sysName) {
        this.sysName = sysName;
    }

    public String getSysDesc() {
        return sysDesc;
    }

    public void setSysDesc(String sysDesc) {
        this.sysDesc = sysDesc;
    }
}

Print the custom properties like this:

package com.test.sb1jt.commands;

import com.test.sb1jt.config.InfoConfig;
import com.test.sb1jt.config.SysConfig;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;

/**
 * Created on 2019/5/22.
 */
@Component
public class MyCommand implements CommandLineRunner {
    private static Logger logger = LoggerFactory.getLogger(MyCommand.class);

    @Autowired
    private SysConfig sysConfig; //inject the sysConfig instance

    @Override
    public void run(String... strings) throws Exception {
        logger.info("MyCommand run");

        logger.info("sysconfig sysname is {},sysdesc is {}",
                sysConfig.getSysName(),sysConfig.getSysDesc());
    }
}

Run the code ,we get this:

2019-05-23 12:45:58.827  INFO 31595 --- [           main] com.test.sb1jt.commands.MyCommand        : sysconfig sysname is BDS,sysdesc is Big data system

4. Conclusion

You can use @Value ,@Configuration to read default application.properties or use the @PropertySource in your custom properties file in SpringBoot apps.