Spring Boot Dev tools: Property defaults

Below table summarizes the properties that are enabled or disabled by spring boot dev tools.

Property	Value
spring.freemarker.cache	False
spring.groovy.template.cache	False
spring.mustache.cache	False
server.servlet.session.persistent	True
spring.h2.console.enabled	True
spring.resources.cache.period	0
spring.resources.chain.cache	False
spring.template.provider.cache	False
spring.mvc.log-resolved-exception	True
server.error.include-stacktrace	ALWAYS
server.servlet.jsp.init-parameters.development	True
spring.thymeleaf.cache	false
spring.reactor.stacktrace-mode.enabled	True

Reference

https://github.com/spring-projects/spring-boot/blob/v2.1.7.RELEASE/spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/env/DevToolsPropertyDefaultsPostProcessor.java

Let’s try to find out the default properties using an application.

Step 1: Create a template project.

Go to 'https://start.spring.io/'.

Give the group as 'com.sample.app', Artifact as 'DevToolDemo'.

Add below dependencies.

a.   Spring Web Starter

b.   Spring Boot DevTools

Click on ‘Generate the project’ button.

Extract the downloaded zip file.

Step 2: Import the maven project from step 1 to Eclipse.

Imported project structure looks like below.

Step 3: Add controller.

Create a package 'com.sample.app.DevToolDemo.controller' and define HomeController.java like below.

HomeController.java

package com.sample.app.DevToolDemo.controller;

import java.util.Iterator;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.env.AbstractEnvironment;
import org.springframework.core.env.Environment;
import org.springframework.core.env.MapPropertySource;
import org.springframework.core.env.PropertySource;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.*;

@RestController
public class HomeController {

    @Autowired
    private Environment env;

    @RequestMapping("/")
    public String homePage() {
        return "Welcome to Spring boot Application Development";
    }

    @RequestMapping("/configs")
    public Map<String, Object> configs() {
        Map<String, Object> properties = new HashMap<>();

        Iterator iterator = ((AbstractEnvironment) env).getPropertySources().iterator();

        while(iterator.hasNext()) {
            PropertySource propertySource = (PropertySource) iterator.next();
            
            if (propertySource instanceof MapPropertySource) {

                String[] propertyNames = ((MapPropertySource) propertySource).getPropertyNames();

                for (String propName : propertyNames) {
                    properties.put(propName, propertySource.getProperty(propName));
                }

            }

        }
        
        return properties;
    }

}

Step 4: Create ‘application.properties’ file under src/main/resources folder.

application.properties

server.port=9999

DevToolDemoApplication.java

package com.sample.app.DevToolDemo;

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

@SpringBootApplication
public class DevToolDemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DevToolDemoApplication.class, args);
    }

}

Total project structure looks like below.

Run DevToolDemoApplication.java.   

Open the url 'http://localhost:9999/configs' in browser, you can see below configurations.

You can confirm the default properties from the same response.

Note

If you don’t want property defaults to be applied you can set spring.devtools.add-properties to false in your application.properties.

You can download complete working application from this link.

Previous                                                    Next                                                    Home