How to Read value From application.properties in spring boot

In Earlier Tutorial We have Learn How to Change the default port in Spring Boot , Here we see how we can read application.properties in spring boot . We have different ways for reading values from application properties ,here we will discuss three ways for reading  keys from application.propeties file as following

• How to read values from application.properties Using @Value annotation
• How to read values from application.properties Using @ConfigurationProperties annotation
• How to read  values from application.properties Using Environment object

How to read value from application.properties Using @Value

Now we see how to read properties file in spring using annotation @Value . If you are in new spring boot and then i will recommencement to you first read how create project in Spring boot . Firstly we will add below values in application.properties file of our project.

Application.properties

email.username=javavogue
email.pwd=12345

Now we will create java Class with name EmailService where we map these  key to class’s field using  @Value as below .

package com.javavogue.demo.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;

@Service
public class EmailService {
	
	 @Value("${email.username}")
	 private String username;
	 
	 @Value("${email.pwd}")
	 private String pwd;

	 @Autowired
	 private EmailConfig emailConfig;
	 
	public void sendEmail(){
	System.out.println("reading value from propertes file using @value annotation");
	System.out.println("username ="+ username);
	System.out.println("pwd ="+ pwd);
				
	}
	
}

How to read value from application.properties Using @ConfigurationProperties

In this we explain How to load properties using Spring Boot @ConfigurationProperties .In this way we will create a plain java object where each class field name same as the key of application.properties. Because In application.properties file we have email string as prefix of key so that we will use email string with @ConfigurationProperties annotation . In below we have given Spring Boot @ConfigurationProperties example 

EmailConfig.java

package com.javavogue.demo.service;

import javax.validation.constraints.Max;
import javax.validation.constraints.Min;

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

@Component
@ConfigurationProperties("email")
public class EmailConfig {
     
  private String   username;
     
    private String  pwd;
     
    public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		this.username = username;
	}
	public String getPwd() {
		return pwd;
	}
	public void setPwd(String pwd) {
		this.pwd = pwd;
	}
		
	@Override
	public String toString() {
		return "EmailConfig [username=" + username + ", pwd=" + pwd + "]";
	}
	
}

How to read application.properties Using using Environment object

Now we will read value from application.propeties file using Environment object. We will pass key in getProperty(“Key”)  method on environment object as

package com.javavogue.demo.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.env.Environment;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import com.javavogue.demo.service.EmailService;

@RestController
public class EmailController {
	
	@Autowired
	private Environment env;

	@GetMapping("/sendmail")
	public void sendMail(){		
System.out.println("values from application properties using Environment ");
System.out.println("username ="+ env.getProperty("email.username"));
System.out.println("pwd ="+ env.getProperty("email.pwd"));
	}
}

In This tutorial we have given three method for reading properties file .

A Guide to Spring Boot

Spring boot doc