How retrieve session value inside servlet

[Suresh Khant]

Hi All,

I have set a session variable inside one of my beans as the following

FacesContext context = FacesContext.getCurrentInstance();
context.getExternalContext().getSessionMap().put("userId",userId);

I can retrieve the value of the session in other beans using the following

FacesContext.getCurrentInstance().getExternalContext().getSessionMap().get("userId");

but the above code fails if i want to retrieve the value inside servlet (doGet method)

[Tim Holloway]

Rule #1 of JSF: the more JSF-specific code you use, the more likely you're doing it wrong.

Forget the FacesContext.

Create the bean named "userId" as a Managed Bean and inject into whatever bean you had been using to do the getSessionMap().put(). Manipulate the userId bean if/when needed using POJO code.

In the servlet, do an HttpServletRequest().getSession().getAttribute('userId") to obtain the bean for servlet code to use.

[Suresh Khant]

Thanks Tim Holloway for your reply ,

I have wrote the following code , but it does not

<managed-bean>
  <managed-bean-name>userBean</managed-bean-name>
  <managed-bean-class>com.beans.UserBean</managed-bean-class>
  <managed-bean-scope>session</managed-bean-scope>
 </managed-bean>

public class UserBean{
	private UserInfo userInfo;

	public User getUserInfo() {
		return this.userInfo;
	}
	public void setUserInfo(UserInfo userInfo) {
		this.userInfo = userInfo;
	}
}

setting the session

	  UserBean userBean = new UserBean();
	  userBean.setUserInfo(userInfo);

	  FacesContext context = FacesContext.getCurrentInstance();
         context.getExternalContext().getSessionMap().put("userBean",userBean);

retreiving the session from servlet

public class UserInfoServlet extends HttpServlet {
	private UserBean userBean;

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

					UserInfo userInfo = ((UserBean) (request.getSession().getAttribute("userBean"))).getUserInfo();
	}

[Tim Holloway]

Forget the FacesContext

You are attempting to "pull" userBean. JSF is based on Inversion of Control, which is "push" based.

<managed-bean>  
   <managed-bean-name>userBean</managed-bean-name>  
   <managed-bean-class>com.beans.UserBean</managed-bean-class>  
   <managed-bean-scope>session</managed-bean-scope>  
</managed-bean>  
<managed-bean>  
   <managed-bean-name>actingBean</managed-bean-name>  
   <managed-bean-class>com.beans.ActingBean</managed-bean-class>  
   <managed-bean-scope>session</managed-bean-scope>  
   <managed-property>
      <property-name>userBean</property-name>
      <value>#{userBean}</value>
  </managed-property>
</managed-bean>  

package com.beans;

public class ActingBean {

private UserBean userBean;

    /**
     * POJO accessor for userBean injected by faces-config.
     * @param userBean The UserBean instance being injected.
    */
    public void setUserBean(UserBean userBean) {
       this.userBean = userBean;
    }

   /**
    * Action method that works with the UserBean. Generally attached
    * to a UI commandButton or commandLink.
    * @return JSF navigation directive. 
    */
    public String doCommand() {
         userBean.doThis();
         userBean.doThat();
         userBean.setLastAccessTime(new java.util.Date());
         return "somewhere";
    }
}

Note that there is no FacesContext - or any other javax.faces import in the above. It accesses userBean in JSF using only POJO techniques.

[Suresh Khant]

Thanks Tim Holloway for your reply ,

Create the bean named "userId" as a Managed Bean and inject into whatever bean you had been using to do the getSessionMap().put(). Manipulate the userId bean if/when needed using POJO code.

In the servlet, do an HttpServletRequest().getSession().getAttribute('userId") to obtain the bean for servlet code to use.

You have not used

getSessionMap().put()

HttpServletRequest().getSession().getAttribute

in your above examples ,


how i can set the session in any other beans and retrieve the session from a servlet or inside a servlet

[Tim Holloway]

I don't need to get the session map in JSF code. JSF does that automatically.

JSF session objects are HTTPSession objects. The only difference between session Managed Beans and bog-standard J2EE session beans is that JSF automatically constructs and initializes them and automatically stores them in the HTTPSession. After that, there's absolutely no way to tell the difference.

[Suresh Khant]

Thanks Tim Holloway for your reply and your effort ,

I apologize you as I am a very slow learner

but the question is that How I can access the session value from servlet ? I have tried below code but it fails.

public class UsersListBean {

.......
	
	public void doSomething(ActionEvent ae) {
	...........
	   	 UserBean userBean = new UserBean();  
		 userBean.setUserInfo(userInfo);  
	   
		 FacesContext context = FacesContext.getCurrentInstance();  
		 context.getExternalContext().getSessionMap().put("userBean",userBean);

	}
}

    public class UserInfoServlet extends HttpServlet {  
      
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {  
      
				HttpSession httpSession = request.getSession();
				UserBean userBean = (UserBean) httpSession.getAttribute("userBean");
				if (userBean!=null)
					Log.getLogger(this.getClass()).info(userBean.getUserInfo.toString());
				else
					Log.getLogger(this.getClass()).info("null");	  
	}  

public class UserBean{  
    private UserInfo userInfo;  
   
    public User getUserInfo() {  
        return this.userInfo;  
    }  
    public void setUserInfo(UserInfo userInfo) {  
        this.userInfo = userInfo;  
    }  
 } 

    <managed-bean>  
      <managed-bean-name>usersListBean</managed-bean-name>  
      <managed-bean-class>com.beans.UsersListBean</managed-bean-class>  
      <managed-bean-scope>request</managed-bean-scope>  
    </managed-bean> 

    <managed-bean>  
      <managed-bean-name>userBean</managed-bean-name>  
      <managed-bean-class>com.beans.UserBean</managed-bean-class>  
      <managed-bean-scope>session</managed-bean-scope>  
    </managed-bean>  

[Tim Holloway]

public class UsersListBean {
private UserBean userBean;

/**
* POJO accessor for userBean injected by faces-config.
* @param userBean The UserBean instance being injected.
*/
public void setUserBean(UserBean userBean) {
this.userBean = userBean;
}

public void doSomething(ActionEvent ae) {
...........
UserBean userBean = new UserBean();
this.userBean.setUserInfo(userInfo);

FacesContext context = FacesContext.getCurrentInstance();
context.getExternalContext().getSessionMap().put("userBean",userBean);
}
}

I removed the ActionEvent parameter because I strongly discourage frivolous use of Listeners. Use a simple POJO action method instead.

You don't need a constructor for userBean because it's a Managed Bean and JSF will construct the UserBean instance for you and store it as a session object in accordance with the faces-config directives supplied.

You don't need FacesContext or the getSessionMap.put operation to store the UserBean as a session object because JSF did that already as part of the process of creating the managed bean, as mentioned above.

All you need to do is use the bean itself. Everything else was done for you automatically by JSF. It's what JSF is all about. Simplification.

Here's the faces-config info that goes with all of the above:

 <managed-bean>    
    <managed-bean-name>userBean</managed-bean-name>    
    <managed-bean-class>com.beans.UserBean</managed-bean-class>    
    <managed-bean-scope>session</managed-bean-scope>    
 </managed-bean>    
 <managed-bean>    
    <managed-bean-name>usersListBean</managed-bean-name>    
    <managed-bean-class>com.beans.UsersListBean</managed-bean-class>    
    <managed-bean-scope>request</managed-bean-scope>    
    <managed-property>  
       <property-name>userBean</property-name>  
       <value>#{userBean}</value>  
   </managed-property>  
 </managed-bean>