Micronaut: type based binding demo

Some parameters in Micronaut are recognized by their type instead of their annotation.

 

For example,

@Get(value = "/type-binding-demo", produces = MediaType.APPLICATION_JSON)
public Map<String, String> demo(final BasicAuth credentials) {

	final Map<String, String> map = new HashMap<>();
	map.put("username", credentials.getUsername());
	map.put("password", credentials.getPassword());

	return map;

}

 

Micronaut map the information from ‘Authorization’ header to the BasicAuth model object.

 

Find the below working application.

 

Step 1: Create new maven project ‘micronaut-type-based-binding’.

 

Step 2: Update pom.xml with maven dependencies.

 

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.sample.app</groupId>
	<artifactId>micronaut-type-based-binding</artifactId>
	<version>0.1</version>
	<packaging>jar</packaging>

	<parent>
		<groupId>io.micronaut</groupId>
		<artifactId>micronaut-parent</artifactId>
		<version>3.7.4</version>
	</parent>

	<properties>
		<packaging>jar</packaging>
		<jdk.version>11</jdk.version>
		<release.version>11</release.version>
		<micronaut.version>3.7.3</micronaut.version>
		<micronaut.runtime>netty</micronaut.runtime>
		<exec.mainClass>com.sample.app.App</exec.mainClass>
	</properties>

	<repositories>
		<repository>
			<id>central</id>
			<url>https://repo.maven.apache.org/maven2</url>
		</repository>
	</repositories>

	<dependencies>
		<dependency>
			<groupId>io.micronaut</groupId>
			<artifactId>micronaut-inject</artifactId>
			<scope>compile</scope>
		</dependency>
		<dependency>
			<groupId>io.micronaut</groupId>
			<artifactId>micronaut-validation</artifactId>
			<scope>compile</scope>
		</dependency>
		<dependency>
			<groupId>io.micronaut</groupId>
			<artifactId>micronaut-http-client</artifactId>
			<scope>compile</scope>
		</dependency>
		<dependency>
			<groupId>io.micronaut</groupId>
			<artifactId>micronaut-http-server-netty</artifactId>
			<scope>compile</scope>
		</dependency>
		<dependency>
			<groupId>io.micronaut</groupId>
			<artifactId>micronaut-jackson-databind</artifactId>
			<scope>compile</scope>
		</dependency>
		<dependency>
			<groupId>jakarta.annotation</groupId>
			<artifactId>jakarta.annotation-api</artifactId>
			<scope>compile</scope>
		</dependency>
		<dependency>
			<groupId>ch.qos.logback</groupId>
			<artifactId>logback-classic</artifactId>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>io.micronaut.test</groupId>
			<artifactId>micronaut-test-junit5</artifactId>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>org.junit.jupiter</groupId>
			<artifactId>junit-jupiter-api</artifactId>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>org.junit.jupiter</groupId>
			<artifactId>junit-jupiter-engine</artifactId>
			<scope>test</scope>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>io.micronaut.build</groupId>
				<artifactId>micronaut-maven-plugin</artifactId>
			</plugin>

			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<configuration>
					<!-- Uncomment to enable incremental compilation -->
					<!-- <useIncrementalCompilation>false</useIncrementalCompilation> -->

					<annotationProcessorPaths
						combine.children="append">
						<path>
							<groupId>io.micronaut</groupId>
							<artifactId>micronaut-http-validation</artifactId>
							<version>${micronaut.version}</version>
						</path>
					</annotationProcessorPaths>

				</configuration>
			</plugin>
		</plugins>
	</build>

</project>

 

Step 3: Define HelloController class.

 

HelloController.java

 

package com.sample.app.controller;

import java.util.HashMap;
import java.util.Map;

import io.micronaut.http.BasicAuth;
import io.micronaut.http.MediaType;
import io.micronaut.http.annotation.Controller;
import io.micronaut.http.annotation.Get;

@Controller("/hello")
public class HelloController {

	@Get(value = "/type-binding-demo", produces = MediaType.APPLICATION_JSON)
	public Map<String, String> demo(final BasicAuth credentials) {

		final Map<String, String> map = new HashMap<>();
		map.put("username", credentials.getUsername());
		map.put("password", credentials.getPassword());

		return map;

	}

}

 

Step 4: Define main application class.

 

App.java

 

package com.sample.app;

import io.micronaut.runtime.Micronaut;

public class App {

	public static void main(String[] args) {

		Micronaut.run(App.class);

		// Use this if you want the beans to be initialized eagerly
		/*
		 * Micronaut.build(args) .eagerInitSingletons(true) .mainClass(App.class)
		 * .start();
		 */
	}
}

 

Total project structure looks like below.

 

Build the project using mvn package command.

Navigate to the folder where pom.xml is located and execute the command ‘mvn package’.

 

Upon command successful execution, you can see the jar file ‘micronaut-type-based-binding-0.1.jar’ in project target folder.

$ls ./target/
classes
generated-sources
generated-test-sources
maven-archiver
maven-status
micronaut-type-based-binding-0.1.jar
original-micronaut-type-based-binding-0.1.jar
test-classes

Execute below command to run the application.

java -jar ./target/micronaut-type-based-binding-0.1.jar

Run below command to validate the api.

curl --location --request GET 'http://localhost:8080/hello/type-binding-demo' \
--header 'Authorization: Basic ZGVtbzpkZW1vMTIz'

$curl --location --request GET 'http://localhost:8080/hello/type-binding-demo' \
--header 'Authorization: Basic ZGVtbzpkZW1vMTIz'
{"password":"demo123","username":"demo"}

You can download this application from this link.

  

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