Spring boot Dev tools: customize restarts

In some scenarios, we may not want to restart the application for specific files, and we may want to include additional folders to be considered for restarting. We can customize this kind of behavior using 'spring.devtools.restart.exclude' and 'spring.devtools.restart.additional-paths' properties.

Example

spring.devtools.restart.exclude=static/**,public/**

spring.devtools.restart.additional-paths=labels/**

Let’s see the same by developing 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
spring.devtools.restart.exclude=static/**,public/**
spring.devtools.restart.additional-paths=labels/**
 

Step 5: Generated DevToolDemoApplication Looks like below.

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);
    }

}

Step 6: Create staticFile.txt under src/main/resources/static folder.

staticFile.txt

Hello

Step 7: Create message.properties file under src/main/resources/labels folder.

message.properties

appName=Chat Server

version=1.23.4

Total project structure looks like below.

Run ‘DevToolDemoApplication.java’.

Update ‘staticFile.txt’ and save the changes, you can observer no restart is triggered by spring boot.

Now update ‘message.properties’ and save the changes, you can observe a restart. You can see below kind of messages in console.

2019-09-04 13:38:57.847  INFO 85732 --- [       Thread-6] o.s.s.concurrent.ThreadPoolTaskExecutor  : Shutting down ExecutorService 'applicationTaskExecutor'

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.1.7.RELEASE)

2019-09-04 13:38:57.959  INFO 85732 --- [  restartedMain] c.s.a.D.DevToolDemoApplication           : Starting DevToolDemoApplication on C02X902SJGH5 with PID 85732 (/Users/krishna/Downloads/DevToolDemo/target/classes started by krishna in /Users/krishna/Downloads/DevToolDemo)
2019-09-04 13:38:57.959  INFO 85732 --- [  restartedMain] c.s.a.D.DevToolDemoApplication           : No active profile set, falling back to default profiles: default
2019-09-04 13:38:58.119  INFO 85732 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 9999 (http)
2019-09-04 13:38:58.120  INFO 85732 --- [  restartedMain] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2019-09-04 13:38:58.120  INFO 85732 --- [  restartedMain] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.22]
2019-09-04 13:38:58.125  INFO 85732 --- [  restartedMain] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2019-09-04 13:38:58.125  INFO 85732 --- [  restartedMain] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 164 ms
2019-09-04 13:38:58.166  INFO 85732 --- [  restartedMain] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
2019-09-04 13:38:58.199  INFO 85732 --- [  restartedMain] o.s.b.d.a.OptionalLiveReloadServer       : LiveReload server is running on port 35729
2019-09-04 13:38:58.210  INFO 85732 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 9999 (http) with context path ''
2019-09-04 13:38:58.210  INFO 85732 --- [  restartedMain] c.s.a.D.DevToolDemoApplication           : Started DevToolDemoApplication in 0.269 seconds (JVM running for 76.506)
2019-09-04 13:38:58.212  INFO 85732 --- [  restartedMain] .ConditionEvaluationDeltaLoggingListener : Condition evaluation unchanged

You can download complete working application from this link.

     

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