Get Request and Session Parameters and Attributes from JSF pages

Question

You can get a request parameter id using the expression:

<h:outputText value="#{param['id']}" />

• param—An immutable Map of the request parameters for this request, keyed by parameter name. Only the first value for each parameter name is included.
• sessionScope—A Map of the session attributes for this request, keyed by attribute name.

Section 5.3.1.2 of the JSF 1.0 specification defines the objects that must be resolved by the variable resolver.

You can also use a bean (request scoped is suggested) and directly access the context by way of the FacesContext.

You can get the HttpServletRequest and HttpServletResposne objects by using the following code:

HttpServletRequest req = (HttpServletRequest)FacesContext.getCurrentInstance().getExternalContext().getRequest();
HttpServletResponse res = (HttpServletResponse)FacesContext.getCurrentInstance().getExternalContext().getResponse();

After this, you can access individual parameters via getParameter(paramName) or access the full map via getParameterMap() req object

The reason I suggest a request scoped bean is that you can use these during initialization (worst case scenario being the constructor. Most frameworks give you some place to do code at bean initialization time) and they will be done as your request comes in.

It is, however, a bit of a hack. ;) You may want to look into seeing if there is a JSF Acegi module that will allow you to get access to the variables you need.

You can either use

<h:outputText value="#{param['id']}" /> or

<h:outputText value="#{request.getParameter('id')}" />

However if you want to pass the parameters to your backing beans, using f:viewParam is probably what you want. "A view parameter is a mapping between a query string parameter and a model value."

<f:viewParam name="id" value="#{blog.entryId}"/>

This will set the id param of the GET parameter to the blog bean's entryId field. See http://java.dzone.com/articles/bookmarkability-jsf-2 for the details.

You can like this:

#{requestScope["paramName"]} ,#{sessionScope["paramName"]}

Because requestScope or sessionScope is a Map object.