Category: quarkus

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Setting and Getting Custom Properties In Quarkus

Often time, when creating web application, you need to set some values in application settings and later, pull such values to display to users.

One of the most prevalent examples is the application’s name and/or application’s version. I’ll show you how to set such values in the app and later, display them in an example endpoint.

Setting custom properties in application.properties

One place you can set custom properties for the application is in application.properties file. For example, I set two properties as follow:

myapp.author=datmt
myapp.created_year=2021

Now, let’s create an endpoint and display those values.

Getting custom properties in REST endpoints

Setting properties was easy, getting them is no exception. Let’s see how I get those values in the follow snippets:

    @ConfigProperty(name = "myapp.author")
    String author;

    @ConfigProperty(name = "myapp.created_year")
    String createdYear;


    @GET
    @Path("info")
    @Produces(MediaType.TEXT_PLAIN)
    public String info() {

        return "App created by " + author + " in the year " + createdYear;

    }

When accessing the URL in my browser, this is the result:

custom properties set in application properties file displayed.

As you can see, the values I set in application.properties file were displayed correctly in the browser.

Setting default fallback value

There are times you want to set a default value for a specific property in case it is not available. You can do that easily with default in @ConfigProperty.

For example, I’ll try to access a property that didn’t set in application.properties file called myapp.language. In @ConfigProperty, besides setting name, I also set a default value:

    @ConfigProperty(name = "myapp.language", defaultValue = "French")
    String language;

In the info method above, I updated the return string to be like so:

    @GET
    @Path("info")
    @Produces(MediaType.TEXT_PLAIN)
    public String info() {

        return "App created by " + author + " in the year " + createdYear + " in " + language;

    }

When viewing on my browser, I got the language displayed as French since there wasn’t any setting for that property in application.properties file:

Getting default property value in JAX-RS

Setting multiple values for property

As you’ve seen above, I set only String to the properties. However, if you want, you can set a list as one property. 

myapp.programming_languages=Java,PHP,JavaScript,Go

I created a new endpoint called language-info with the following details:

    @GET
    @Path("language-info")
    @Produces(MediaType.TEXT_PLAIN)
    public String languageInfo() {

        return  String.join(",", languages);
    }

Sure enough, when visiting the endpoint, I got the expected result:

In case you have multiple properties and don’t want to inject each property separately, you can inject Config object:

    @Inject
    Config config;

and get the value using getValue.

String appLanguage = config.getValue("myapp.language", String.class);
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Create Quarkus Project Under 5 Minutes With Live Reloading

Creating Quarkus project is quite simple. You can get started in just a few minutes. In this post, I’m going to show you how you can do that.

My assumption is you have maven installed. If you don’t, please follow the guide to install it here.

After you have maven installed, it very easy to create quarkus project.

Step by step to create Quarkus project

mvn io.quarkus:quarkus-maven-plugin:1.13.2.Final:create \
    -DprojectGroupId=quarkus-project-groupId \
    -DprojectArtifactId=myquarkus-project-artifactId \
    -DprojectVersion=1.0.0-SNAPSHOT \
    -DclassName="com.datmt.QuarkusStart" \
    -Dpath="/get-started"

As you can see, in the create command, you can specify group ID, artifact ID, project version, a starter class name and a resource path.

Remember that if you define a resource path, you need to specify a class name too. In my case, the class name is com.datmt.QuarkusStart.

After you enter the command above, mvn will take a few minutes to scaffold the project for you.

Maven start to create quarkus project
Maven start to create quarkus project

If everything is OK, you should see a message says the project has successfully built:

create quarkus starter project successfully.

Here is the project’s structure. As I use IntelliJ, there is a .idea folder. That’s not part of the project.

Quarkus project structure

There are a few interesting files you can notice. You have Docker files to build the images. You also have tests and most interesting of all is QuarkusStart.java. This is the file we declared when creating the project.

This is the file content:

package com.datmt;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;

@Path("/C:/Program Files/Git/get-started")
public class QuarkusStart {

    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String hello() {
        return "Hello RESTEasy";
    }
}

As you can see, the path seems wrong. I’ll need to modify it as follow:

package com.datmt;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;

@Path("/get-started")
public class QuarkusStart {

    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String hello() {
        return "Hey quarkus starter";
    }
}

Running Quarkus application

Now, let’s run the app and check if we can get the the path /get-started up and running. In the root folder of the project, run

./mvnw compile quarkus:dev

If you are on Windows, you may need to remove the ./ part.

If everything is OK, you should see a message says that quarkus is listening on port 8080:

Now, let’s navigate to http://localhost:8080/get-started, we get what is expected:

As mentioned at the title of the post, by running with …quarkus:dev, you will have live reload (or hot reload) enabled. That means as you make changes in code, you can see the changes in the services without stop and run the project again.