Micronaut: Bind HTTP header to a method parameter

@Header annotation can be applied to method argument to indicate that the method argument is bound from an HTTP header.

 

Example

@Get(value = "/headers", produces = MediaType.TEXT_PLAIN)
public String printHeaders(@Header("Content-Type") String contentType, @Header("secret-key") String secretKey) {

	final StringBuilder builder = new StringBuilder();
	builder.append("contentType").append("=").append(contentType);
	builder.append("\n");
	builder.append("secretKey").append("=").append(secretKey);

	return builder.toString();
}

Find the below working application.

 

Step 1: Create new maven project ‘micronaut-rest-bind-request-header’.

 

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-rest-bind-request-header</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 io.micronaut.http.MediaType;
import io.micronaut.http.annotation.Controller;
import io.micronaut.http.annotation.Get;
import io.micronaut.http.annotation.Header;

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

	@Get(value = "/headers", produces = MediaType.TEXT_PLAIN)
	public String printHeaders(@Header("Content-Type") String contentType, @Header("secret-key") String secretKey) {

		final StringBuilder builder = new StringBuilder();
		builder.append("contentType").append("=").append(contentType);
		builder.append("\n");
		builder.append("secretKey").append("=").append(secretKey);

		return builder.toString();
	}
}

 

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-rest-bind-request-header-0.1.jar’ in project target folder.

$ls ./target/
classes
generated-sources
generated-test-sources
maven-archiver
maven-status
micronaut-rest-bind-request-header-0.1.jar
original-micronaut-rest-bind-request-header-0.1.jar
test-classes

 

Execute below command to run the application.

java -jar ./target/micronaut-rest-bind-request-header-0.1.jar

 

Execute below command to check the api functionality.

curl --location --request GET 'http://localhost:8080/hello/headers' \
--header 'Content-Type: application/json' \
--header 'secret-key: sec1234567'

$curl --location --request GET 'http://localhost:8080/hello/headers' \
--header 'Content-Type: application/json' \
--header 'secret-key: sec1234567'
contentType=application/json
secretKey=sec1234567

 

You can download this application from this link.

 

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