In this post we will see how to access and modify http cookies of a webpage in Spring MVC framework.
Read Http Cookie in Spring MVC
Spring 3 MVC framework provides a very useful annotation @CookieValue to
access data set within any http cookie. This annotation can be leverage to fetch the cookie value without getting into hassle of fetching cookies from http request and iterating through the list.
@CookieValue annotation can be used within Controller argument. It automatically bind the cookie value with method argument.
import
org.springframework.web.bind.annotation.CookieValue;import
org.springframework.web.bind.annotation.RequestMapping;//..@RequestMapping("/hello.html")public
String hello(@CookieValue("foo")
String fooCookie) { //..} |
In above code snippet we defined a controller method hello() which is mapped to URL /hello.html. Also we bind the parameter String
fooCookie using @CookieValue annotation.
When spring maps the request, it checks http for cookie with name “foo”
and bind its value to String fooCookie.
No boiler plate code to iterate though list of cookies, just one line will do it all.
One thing worth noting here is that we have not defined any default value for the String fooCookie. If Spring does not find the cookie with name “foo” in http request, it will throw an exception: java.lang.IllegalStateException: Missing cookie value ‘foo’ of type
java.lang.IllegalStateException:
Missing cookie value 'foo' of type java.lang.String at
org.springframework.web.bind.annotation.support.HandlerMethodInvoker.raiseMissingCookieException(HandlerMethodInvoker.java:796) at
org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveCookieValue(HandlerMethodInvoker.java:684) at
org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveHandlerArguments(HandlerMethodInvoker.java:357) at
org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:171) at
org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:440) at
org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:428) |
In order to resolve this we must add default value to @CookieValue annotation so if Spring doesn’t find http cookie with that name, it binds the parameter with default value. Following is syntax for that:
import
org.springframework.web.bind.annotation.CookieValue;import
org.springframework.web.bind.annotation.RequestMapping;//..@RequestMapping("/hello.html")public
String hello( @CookieValue(value
= "foo",
defaultValue = "hello")
String fooCookie) { //..} |
We used value and defaultValue attribute of @CookieValue annotation. Thus if Spring doesn’t find any cookie with name ‘foo’ in http request, it binds the fooCookie parameter with value ‘hello’.
Setting Http Cookie in Spring MVC
We just saw how we can use @CookieValue annotation to auto-magically bind cookie value with a spring controller parameter.
Now let us see how to set a cookie in a Spring MVC based application. For this actually we will use HttpServletResponse class’s method addCookie(). Spring does not provide any fancy way to set http cookie because it’s already taken care by servlets HttpServletResponse
class. All you need to do it to use just one method addCookie(). Spring MVC can be used to get the responseobject.
Once we have this object it’s just piece of cake.
Consider below code:
import
javax.servlet.http.Cookie;import
javax.servlet.http.HttpServletResponse;import
org.springframework.web.bind.annotation.CookieValue;import
org.springframework.web.bind.annotation.RequestMapping;//..@RequestMapping("/hello.html")public
String hello(HttpServletResponse response) { response.addCookie(new
Cookie("foo",
"bar")); //..
}//.. |
In above code we just bind HttpServletResponse object to Spring method controller and used itsaddCookie method
to save new Cookie. That’s it. One line of code will do it. One thing worth noticing here is that you can set the cookie expire time using setMaxAge method on Cookie class.
Cookie
foo = new
Cookie("foo",
"bar");
//bake
cookiefoo.setMaxAge(1000);
//set
expire time to 1000 sec response.addCookie(foo);
//put
cookie in response |
Complete Tutorial
Now we know the concept, let us use it and create a Spring MVC based application to track page hits. We will use Cookie to track page hit counter.
For this tutorial I will be using following tools and technologies:
- Spring MVC 3.2.6.RELEASE
- Java 6
- Eclipse
- Maven 3
Following is the project structure.
Create and copy following file contents in the project structure.
Maven configuration: pom.xml
<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/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>net.viralpatel.spring</groupId> <artifactId>Spring_Cookie_example</artifactId> <packaging>war</packaging> <version>1.0.0-SNAPSHOT</version> <name>SpringMVCCookie</name> <properties> <org.springframework.version>3.2.6.RELEASE</org.springframework.version> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <compileSource>1.6</compileSource> </properties> <dependencies> <dependency> <groupId>javax.servlet</groupId> <artifactId>servlet-api</artifactId> <version>2.5</version> <scope>provided</scope> </dependency> <!--
Spring MVC --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> <version>${org.springframework.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>${org.springframework.version}</version> </dependency> <!--
JSTL taglib --> <dependency> <groupId>taglibs</groupId> <artifactId>standard</artifactId> <version>1.1.2</version> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>jstl</artifactId> <version>1.1.2</version> </dependency> </dependencies> <build> <finalName>springcookie</finalName> </build> <profiles> </profiles></project> |
Maven configuration is simple. We just need Spring MVC and JSTL dependency.
Deployment description: web.xml
<?xml
version="1.0"
encoding="UTF-8"?><web-app
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID"
version="2.5"> <display-name>Spring
MVC Http Cookie</display-name> <welcome-file-list> <welcome-file>hello.htm</welcome-file> </welcome-file-list> <servlet> <servlet-name>spring</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>spring</servlet-name> <url-pattern>*.htm</url-pattern> </servlet-mapping></web-app> |
Web.xml is quite simple too. We just need to configure Spring’s DispatcherServlet with *.htmurl
pattern.
Spring Configuration: spring-servlet.xml
<?xml
version="1.0"
encoding="UTF-8"?><beans
xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd"> <context:annotation-config
/> <context:component-scan
base-package="net.viralpatel.spring"
/> <bean
id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property
name="viewClass" value="org.springframework.web.servlet.view.JstlView"
/> <property
name="prefix"
value="/WEB-INF/jsp/"
/> <property
name="suffix"
value=".jsp"
/> </bean> </beans> |
In spring-servlet.xml we
just defined component scan to load @Controller classes. Also we defined a view resolver that will points to JSPs within /WEB-INF/jsp/ folder.
JSP file: hello.jsp
<%@
taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %><html><head> <title>Spring
MVC Cookie example</title>
</head><body> <h1>Spring
MVC Cookie example</h1> Page
hit counter: <b>
${cookie.hitCounter.value} </b></body></html> |
This JSP displays the hit counter. It prints the counter value using tag${cookie.hitCounter.value}.
Spring Controller: HelloController.java
package
net.viralpatel.spring;import
javax.servlet.http.Cookie;import
javax.servlet.http.HttpServletResponse;import
org.springframework.stereotype.Controller;import
org.springframework.web.bind.annotation.CookieValue;import
org.springframework.web.bind.annotation.RequestMapping;@Controllerpublic
class
HelloController { @RequestMapping(value
= "/hello.htm") public
String hello( @CookieValue(value
= "hitCounter",
defaultValue = "0")
Long hitCounter, HttpServletResponse
response) { //
increment hit counter hitCounter++; //
create cookie and set it in response Cookie
cookie = new
Cookie("hitCounter",
hitCounter.toString()); response.addCookie(cookie); //
render hello.jsp page return
"hello"; }} |
The logic to fetch hit counter from cookie and set it back is written in HelloController. We used@CookieValue annotation
to map hitCounter cookie
to Long
hitCounter parameter. Notice how we mapped java.lang.Long value.
Spring automatically converts String from Cookie to Long value.
Demo
Open your favorite web browser and point to below URL:
http://localhost:8080/Spring_Cookie_Example/hello.htm
Refresh page 2-3 times and see how hit counter value is incremented.
