How To Get HTTP Request Header In Java

This example shows you how to get the HTTP request headers in Java. To get the HTTP request headers, you need this class HttpServletRequest :

1. HttpServletRequest Examples

1.1 Loop over the request header’s name and print out its value.

WebUtils.java

package com.favtuts.http;

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

import javax.servlet.http.HttpServletRequest;

public class WebUtils {
    
    private Map<String, String> getHeadersInfo(HttpServletRequest request) {

        Map<String, String> map = new HashMap<String, String>();

        Enumeration headerNames = request.getHeaderNames();
        while (headerNames.hasMoreElements()) {
            String key = (String) headerNames.nextElement();
            String value = request.getHeader(key);
            map.put(key, value);
        }

        return map;
    }

}

To use HttpServletRequest or HttpServletResponse in a development environment, include servlet-api.jar in your Maven pom.xml file.

pom.xml

    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.1.0</version>
      <scope>provided</scope>
    </dependency>

Put scope as provided, because most j2ee containers have this jar. You need this for complication only, not deployment.

Request Headers example :

"headers" : {
	"Host" : "tuts.heomi.net",
	"Accept-Encoding" : "gzip,deflate",
	"X-Forwarded-For" : "66.249.x.x",
	"X-Forwarded-Proto" : "http",
	"User-Agent" : "Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)",
	"X-Request-Start" : "1389158003923",
	"Accept" : "*/*",
	"Connection" : "close",
	"X-Forwarded-Port" : "80",
	"From" : "googlebot(at)googlebot.com"
}

1.2 Get the “user-agent” header only.

WebUtils.java

package com.favtuts.http;

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

import javax.servlet.http.HttpServletRequest;

public class WebUtils {
    
    private String getUserAgent(HttpServletRequest request) {
        return request.getHeader("user-agent");
    }
}

User agent example :

Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)

2. Spring MVC Example

In Spring MVC, you can @Autowired the HttpServletRequest into any Spring managed bean directly.

SiteController.java

package com.favtuts.web.controller;

import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.servlet.ModelAndView;

@Controller
@RequestMapping("/site")
public class SiteController {

	@Autowired
	private HttpServletRequest request;

	@RequestMapping(value = "/{input:.+}", method = RequestMethod.GET)
	public ModelAndView getDomain(@PathVariable("input") String input) {

		ModelAndView modelandView = new ModelAndView("result");

		modelandView.addObject("user-agent", getUserAgent());
		modelandView.addObject("headers", getHeadersInfo());

		return modelandView;

	}

	//get user agent
	private String getUserAgent() {
		return request.getHeader("user-agent");
	}

	//get request headers
	private Map<String, String> getHeadersInfo() {

		Map<String, String> map = new HashMap<String, String>();

		Enumeration headerNames = request.getHeaderNames();
		while (headerNames.hasMoreElements()) {
			String key = (String) headerNames.nextElement();
			String value = request.getHeader(key);
			map.put(key, value);
		}

		return map;
	}

}

Declare this dependency in pom.xml, if HttpServletRequest is unable to find.

	<dependency>
		<groupId>javax.servlet</groupId>
		<artifactId>servlet-api</artifactId>
		//<version>2.5</version>
                <version>3.1.0</version>
	</dependency>

References

1. Wikipedia – List of HTTP header fields
2. How To Get Http Response Header In Java