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.mkyong.web.utils;
import javax.servlet.http.HttpServletRequest;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;
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;
}
}
Request Headers example :
"headers" : {
"Host" : "mkyong.com",
"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.mkyong.web.utils;
import javax.servlet.http.HttpServletRequest;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;
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.mkyong.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>
</dependency>
Spring Controller is singleton, if @autowrie request in controller, I think the injected request would be shared by all clients and leads to chaos. Isn’t it?
no it’s safe. because you get this request from ThreadLocal
Hi MKYong,
I doubt what you said as following :
“In Spring MVC, you can @Autowired the HttpServletRequest into any Spring managed bean directly.
i DISAGREE this:
you mean if even Spring Bean is at data layer , you still want to inject httpRequest there?
is this confirmed to the Java encapsulation principle?? and best practice?, and it is secure? , so we don’t care any layer , tier or any isolation and coupling anymore? Just do what ever people want ? when Strut come out and other framework come out , it also support directly call database from web page … it is “can” but we all know we shouldn’t , so I think you put this suggestion here is really nor proper…
we think what you efforts and those nice examples , however, you may want to be more professional, right?
Thx
the main thing is confused me is ” any” otherwise it is good , so I dont ahree any, you like for all Spring beans include DAO beans?
Hi MKYong,
I doubt what you said as following :
“In Spring MVC, you can @Autowired the HttpServletRequest into any Spring managed bean directly.
i DISAGREE this:
you mean if even Spring Bean is at data layer , you still want to inject httpRequest there?
is this confirmed to the Java encapsulation principle?? and best practice?, and it is secure? , so we don’t care any layer , tier or any isolation and coupling anymore? Just do what ever people want ? when Strut come out and other framework come out , it also support directly call database from web page … it is “can” but we all know we shouldn’t , so I think you put this suggestion here is really nor proper…
we think what you efforts and those nice examples , however, you may want to be more professional, right?
Thx
Hi MKYong,
I doubt what you said as following is right way:
“In Spring MVC, you can @Autowired the HttpServletRequest into any Spring managed bean directly.
and I disagree:
you mean if even Spring Bean is at data layer , you still want to inject httpRequest there?
is this confirmed to the Java encapsulation principle?? and best practice?, and it is secure? , so we don’t care any layer , tier or any isolation and coupling anymore? Just do what ever people want ?
when Strut come out and other framework come out ,they also support directly call database from web page … it is “can” but we all know we shouldn’t , so I think you put this suggestion here is really not proper…
we think what you efforts and those nice examples are good , however, you may want to give proper scope for the HttpServletRequest to use , right?
Thx
Hello Mr.Yong,
I can not test this first example, when I try to execute it on my laptop it happens the following:
javac HttpServletRequest.java
HttpServletRequest.java:4: error: class, interface, or enum expected
private HttpServletRequest request;
^
HttpServletRequest.java:7: error: class, interface, or enum expected
private Map getHeadersInfo() {
^
HttpServletRequest.java:11: error: class, interface, or enum expected
Enumeration headerNames = request.getHeaderNames();
^
HttpServletRequest.java:12: error: class, interface, or enum expected
while (headerNames.hasMoreElements()) {
^
HttpServletRequest.java:14: error: class, interface, or enum expected
String value = request.getHeader(key);
^
HttpServletRequest.java:15: error: class, interface, or enum expected
map.put(key, value);
^
HttpServletRequest.java:16: error: class, interface, or enum expected
}
^
HttpServletRequest.java:19: error: class, interface, or enum expected
}
^
8 errors
Do you know what I’m doing wrong?
BR
is is possible to get the request line using HttpServletRequest? I want to use it to distinguish the proxy request and server request. Yes I know Tomcat don’t support proxy alone, but I don’t want to install httpd or nginx on my server for some non-technical reason.
What about cases where headers with the same name (but with different values) appear in the request? It may not be common in practice but the HTTP 1.1 specification permits it.
thanks! what about the concurrent calls on the request property? will this work in the right way? thanks again!
what does this mean
@RequestMapping(value = “/{input:.+}”, method = RequestMethod.GET)
why you put “:.+” i am totally confused why you use this and whts its benifit