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.
@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.
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.
<?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.
<?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.
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.
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.
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.
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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