RequestContextHolder is a spring API for setting the values to any of three scopes request, session or global session. Note that in some situations, we may not be able to get the actual request from the request, we can simply use RequestContextHolder to get the request attributes and set the values. We have to explicitly pass the scope id as the parameter. RequestContextHolder has the following three methods:
- currentRequestAttributes() – Return the RequestAttributes currently bound to the thread.
- getRequestAttributes() – Return the RequestAttributes currently bound to the thread.
- resetRequestAttributes() – Reset the RequestAttributes for the current thread.
- setRequestAttributes(RequestAttributes attributes) – Bind the given RequestAttributes to the current thread, not exposing it as inheritable for child threads.
- setRequestAttributes(RequestAttributes attributes, boolean inheritable) – Bind the given RequestAttributes to the current thread.
Lets look at the example.
1. Spring MVC Controller
SpringMVCController.java
package javabeat.net.spring.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.context.request.RequestAttributes;
import org.springframework.web.context.request.RequestContextHolder;
@Controller
public class SpringMVCController {
@RequestMapping(value = "/springmvctest", method = RequestMethod.GET)
public String redirectTest() {
//Setting value to HttpSession object
RequestContextHolder.getRequestAttributes().setAttribute("KEY_VALUE",
"TEST_VALUE", RequestAttributes.SCOPE_SESSION);
return "hello";
}
}
2. Views
hello.jsp
<html>
<body>
<h1>JavaBeat Spring MVC - RequestContextHolder</h1>
<h2>Session Value : ${KEY_VALUE}</h2>
</body>
</html>
3. Spring Configurations
spring-dispatcher-servlet.xml
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:context="http://www.springframework.org/schema/context" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> <context:component-scan base-package="javabeat.net.spring.controller" /> <bean id="jspViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="prefix" value="/WEB-INF/jsp/" /> <property name="suffix" value=".jsp" /> </bean> </beans>
4. Deployment Descriptor
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_3_0.xsd"
id="WebApp_ID" version="3.0">
<display-name>Spring MVC Web Application</display-name>
<servlet>
<servlet-name>spring-dispatcher</servlet-name>
<servlet-class>
org.springframework.web.servlet.DispatcherServlet
</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>spring-dispatcher</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>
5. RequestContextHolder Demo
PrimeFaces + Spring Data + Neo4j Integration