Spring @RequestHeader

last modified October 18, 2023

In this article we show how to bind method parameters to request headers with @RequestHeader annotation.

Spring is a popular Java application framework for creating enterprise applications.

Spring @RequestHeader

@RequestHeader annotation binds request header values to method parameters. If the method parameter is Map<String, String>, MultiValueMap<String, String>, or HttpHeaders then the map is populated with all header names and values.

Spring @RequestHeader example

The application binds request body headers to method parameters. Requests are created with curl tool.

pom.xml src ├───main │ ├───java │ │ └───com │ │ └───zetcode │ │ ├───config │ │ │ MyWebInitializer.java │ │ │ WebConfig.java │ │ └───controller │ │ MyController.java │ └───resources │ logback.xml └───test └───java

This is the project structure.

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.zetcode</groupId>
<artifactId>springrequestheader</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>war</packaging>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>17</maven.compiler.source>
    <maven.compiler.target>17</maven.compiler.target>
    <spring-version>5.3.23</spring-version>
</properties>

<dependencies>

    <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-classic</artifactId>
        <version>1.4.0</version>
    </dependency>

    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>4.0.1</version>
        <scope>provided</scope>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>${spring-version}</version>
    </dependency>

</dependencies>

<build>
    <plugins>

        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-war-plugin</artifactId>
            <version>3.3.2</version>
        </plugin>

        <plugin>
            <groupId>org.eclipse.jetty</groupId>
            <artifactId>jetty-maven-plugin</artifactId>
            <version>9.4.49.v20220914</version>
        </plugin>

    </plugins>
</build>

</project>

We declare the necessary dependencies in pom.xml.

resources/logback.xml

<?xml version=“1.0” encoding=“UTF-8”?> <configuration> <logger name=“org.springframework” level=“ERROR”/> <logger name=“com.zetcode” level=“INFO”/>

<appender name="consoleAppender" class="ch.qos.logback.core.ConsoleAppender">
    <encoder>
        <Pattern>%d{HH:mm:ss.SSS} %blue(%-5level) %magenta(%logger{36}) - %msg %n
        </Pattern>
    </encoder>
</appender>

<root>
    <level value="INFO" />
    <appender-ref ref="consoleAppender" />
</root>

</configuration>

The logback.xml is a configuration file for the Logback logging library.

com/zetcode/config/MyWebInitializer.java

package com.zetcode.config;

import org.springframework.context.annotation.Configuration; import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

@Configuration public class MyWebInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {

@Override
protected Class<?>[] getRootConfigClasses() {
    return null;
}

@Override
protected Class<?>[] getServletConfigClasses() {

    return new Class[]{WebConfig.class};
}

@Override
protected String[] getServletMappings() {

    return new String[]{"/"};
}

}

MyWebInitializer registers the Spring DispatcherServlet, which is a front controller for a Spring web application.

com/zetcode/config/WebConfig.java

package com.zetcode.config;

import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.Configuration; import org.springframework.web.servlet.config.annotation.EnableWebMvc; import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration @EnableWebMvc @ComponentScan(basePackages = {“com.zetcode”}) public class WebConfig implements WebMvcConfigurer {

}

The WebConfig enables Spring MVC annotations with @EnableWebMvc and configures component scanning for the com.zetcode package.

com/zetcode/controller/MyController.java

package com.zetcode.controller;

import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.http.HttpStatus; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.RequestHeader; import org.springframework.web.bind.annotation.ResponseStatus; import org.springframework.web.bind.annotation.RestController;

import java.util.Map;

@RestController public class MyController {

private static final Logger logger = LoggerFactory.getLogger(MyController.class);

@GetMapping(value = "/agent")
@ResponseStatus(value = HttpStatus.OK)
public void client(@RequestHeader(value="User-Agent") String userAgent) {

    logger.info("User agent is: {}", userAgent);
}

@GetMapping(value = "/all")
@ResponseStatus(value = HttpStatus.OK)
public void all(@RequestHeader Map<String, String> headers) {

    logger.info("All headers: {}", headers);
}

}

We have two mappings. The first mapping determines the user agent, the second mapping finds out all request headers sent.

public void client(@RequestHeader(value=“User-Agent”) String userAgent) {

With the value parameter of the @RequestHeader, we look for a specific header; in our case, a User-Agent.

public void all(@RequestHeader Map<String, String> headers) {

When providing a map, we retrieve all headers.

$ mvn jetty:run

We start the server.

$ curl localhost:8080/agent

We create a request to the first mapping.

11:33:00.905 INFO com.zetcode.controller.MyController - User agent is: curl/7.81.0

We get this log.

$ curl localhost:8080/all

We invoke the second mapping.

11:34:59.100 INFO com.zetcode.controller.MyController - All headers: {Accept=/, User-Agent=curl/7.81.0, Host=localhost:8080}

We have three headers logged.

In this article we have used the @RequestHeader annotation to bind request headers to method parameters.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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