Spring Boot (3) Configurations

This section describes the configurations in Spring Boot.

1. Get configuration by ConfigurableApplicationContext object

application.properties

# Common properties
server.port = 8090
server.context-path=/properties
server.session.timeout=1800

package com.my.study.properties;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;

@SpringBootApplication
public class Main {
	public static void main(String[] args) {
		ConfigurableApplicationContext context = SpringApplication.run(Main.class, args);

		// Get properties from ConfigurableApplicationContext
		String serverPort = context.getEnvironment().getProperty("server.port");
		System.out.println("Server port: " + serverPort);
	}
}

2. Get configuration by @Value annotation

application.properties

# Customized properties
user1.name=sunny-dev
user1.age=32-dev

package com.my.study.properties.module;

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

@Component
public class User1 {
	// Use @Value annotation to inject properties, default to use application.properties
	@Value("${user1.name}")
	private String name;
	@Value("${user1.age}")
	private String age;

	public String getName() {
		return name;
	}

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

	public String getAge() {
		return age;
	}

	public void setAge(String age) {
		this.age = age;
	}
}

3. Get configuration by @PropertySource

If you add another properties files, then you need to use @PropertySource to specify the location of this file, then use @Value to inject properties.

customized.properties

# Customized properties
user2.name=Tom
user2.age=33

package com.my.study.properties.module;

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

@Component
// Specify properties file to use
@PropertySource("classpath:customized.properties")
public class User2 {
	// Use @Value annotation to inject properties
	@Value("${user2.name}")
	private String name;
	@Value("${user2.age}")
	private String age;

	public String getName() {
		return name;
	}

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

	public String getAge() {
		return age;
	}

	public void setAge(String age) {
		this.age = age;
	}
}

4. Create a configuration class with annotation @org.springframework.context.annotation.Configuration

We use this configuration class to load all properties files at one place, it's convenient for properties management.

package com.my.study.properties.config;

import org.springframework.context.annotation.PropertySource;

@org.springframework.context.annotation.Configuration
@PropertySource("classpath:customized2.properties")
@PropertySource("classpath:random.properties")
public class Configuration {
}

5. Get configuration by @ConfigurationProperties

customized2.properties

# Customized properties
user3.name=Xiaoming
user3.age=30

package com.my.study.properties.module;

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

@Component
// No need to specify properties file here, because Configuration.java contains this clarification.
// Use @ConfigurationProperties to inject user3.name and user3.age to this class
@ConfigurationProperties(prefix = "user3")
public class User3 {
        // No need to add @Value annotation here
	private String name;
	private String age;

	public String getName() {
		return name;
	}

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

	public String getAge() {
		return age;
	}

	public void setAge(String age) {
		this.age = age;
	}
}

6. Switch multiple environments
application-dev.properties

# Customized properties
user1.name=sunny-dev
user1.age=32-dev

application-test.properties

# Customized properties
user1.name=sunny-test
user1.age=32-test

application-pro.properties

# Customized properties
user1.name=sunny-pro
user1.age=32-pro

application.properties

# Specify deploy mode 'dev', then spring boot will use configuration file application-dev.properties
# Then no need to configure application-xxx.properties in Configuration.java manually.
spring.profiles.active=dev

7. Random properties
random.properties

# Random value
com.test.value=${random.value}
# Random int value
com.test.number=${random.int}
# Random long value
com.test.bignumber=${random.long}
# Random int value in [0, 10)
com.test.random1=${random.int(10)}
# Random int value in [10, 20]
com.test.random2=${random.int[10,20]}

8. Testing Controller

package com.my.study.properties.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.env.Environment;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.my.study.properties.module.RandomVal;
import com.my.study.properties.module.User1;
import com.my.study.properties.module.User2;
import com.my.study.properties.module.User3;

@RestController
public class TestController {

	@Autowired
	private User1 user1;

	@Autowired
	private User2 user2;

	@Autowired
	private User3 user3;

	@Autowired
	private RandomVal randomVal;

	// Get properties from Environment object
      @Autowired
      private Environment env;

	@RequestMapping("/user1")
	public ResponseEntity<User1> showUser() {
		return new ResponseEntity<>(user1, HttpStatus.OK);
	}

	@RequestMapping("/user2")
	public ResponseEntity<User2> showUser2() {
		return new ResponseEntity<>(user2, HttpStatus.OK);
	}

	@RequestMapping("/port")
	public String getServerPort() {
		return env.getProperty("server.port");
	}

	@RequestMapping("/user3")
	public ResponseEntity<User3> showUser3() {
		return new ResponseEntity<>(user3, HttpStatus.OK);
	}

	@RequestMapping("/random")
	public ResponseEntity<RandomVal> showRandomVals() {
		return new ResponseEntity<>(randomVal, HttpStatus.OK);
	}
}

9. Code structure

10. Useful and all common properties

application.properties

# Common properties
server.port = 8090
server.context-path=/properties
server.session.timeout=1800

For all common properties, please refer to:
https://docs.spring.io/spring-boot/docs/1.5.8.RELEASE/reference/html/common-application-properties.html

For all Spring Boot guide, please refer to:
https://docs.spring.io/spring-boot/docs/1.5.8.RELEASE/reference/html/

Spring Boot (3) Configurations

Spring Boot (3) Configurations

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