# 13. JSF Integration
## 13.1. Introduction
Spring Web Flow provides a JSF integration that lets you use the JSF UI
Component Model with Spring Web Flow controllers. Web Flow also provides
a Spring Security tag library for use in JSF environments,
see [Section 13.9, “Using the Spring Security Facelets Tag Library”](spring-faces.html#spring-faces-security-taglib) for more details.
Spring Web Flow 2.5 requires JSF 2.2 or higher.
## 13.2. Configuring web.xml
The first step is to route requests to the`DispatcherServlet` in the `web.xml` file. In this
example, we map all URLs that begin with `/spring/` to the
servlet. The servlet needs to be configured. An `init-param` is
used in the servlet to pass the `contextConfigLocation`. This
is the location of the Spring configuration for your web
application.
```
Spring MVC Dispatcher Servletorg.springframework.web.servlet.DispatcherServletcontextConfigLocation/WEB-INF/web-application-config.xml1Spring MVC Dispatcher Servlet/spring/*
```
In order for JSF to bootstrap correctly, the`FacesServlet` must be configured in `web.xml` as it
normally would even though you generally will not need to route requests
through it at all when using JSF with Spring Web Flow.
```
Faces Servletjavax.faces.webapp.FacesServlet1Faces Servlet*.faces
```
The use of Facelets instead of JSP typically requires this in
web.xml:
```
!-- Use JSF view templates saved as *.xhtml, for use with Facelets -->
javax.faces.DEFAULT_SUFFIX.xhtml
```
## 13.3. Configuring Web Flow for use with JSF
This section explains how to configure Web Flow with JSF.
Both Java and XML style configuration are supported.
The following is sample configuration for Web Flow and JSF in XML:
```
```
The following is an example of the same in Java configuration:
```
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.faces.config.*;
@Configuration
public class WebFlowConfig extends AbstractFacesFlowConfiguration {
@Bean
public FlowExecutor flowExecutor() {
return getFlowExecutorBuilder(flowRegistry())
.addFlowExecutionListener(new FlowFacesContextLifecycleListener())
.build();
}
@Bean
public FlowDefinitionRegistry flowRegistry() {
return getFlowDefinitionRegistryBuilder()
.setBasePath("/WEB-INF")
.addFlowLocationPattern("**/*-flow.xml").build();
}
```
The main points are the installation of a`FlowFacesContextLifecycleListener` that manages a single
FacesContext for the duration of Web Flow request and the use of the`flow-builder-services` element from the `faces`custom namespace to configure rendering for a JSF environment.
In a JSF environment you'll also need this Spring MVC related
configuration:
```
```
The `resources` custom namespace element delegates JSF
resource requests to the JSF resource API. The`JsfFlowHandlerAdapter` is a replacement for the`FlowHandlerAdapter` normally used with Web Flow. This adapter
initializes itself with a `JsfAjaxHandler` instead of the`SpringJavaSciprtAjaxHandler`.
When using Java config, the `AbstractFacesFlowConfiguration`base class automatically registers `JsfResourceRequestHandler`so there is nothing further to do.
## 13.4. Replacing the JSF Managed Bean Facility
When using JSF with Spring Web Flow you can completely replace the
JSF managed bean facility with a combination of Web Flow managed variables
and Spring managed beans. It gives you a good deal more control over the
lifecycle of your managed objects with well-defined hooks for
initialization and execution of your domain model. Additionally, since you
are presumably already using Spring for your business layer, it reduces
the conceptual overhead of having to maintain two different managed bean
models.
In doing pure JSF development, you will quickly find that request
scope is not long-lived enough for storing conversational model objects
that drive complex event-driven views. In JSF the usual option is to begin
putting things into session scope, with the extra
burden of needing to clean the objects up before progressing to another
view or functional area of the application. What is really needed is a
managed scope that is somewhere between request and session scope. JSF
provides flash and view scopes that can be accessed programmatically via
UIViewRoot.getViewMap(). Spring Web Flow provides access to flash, view,
flow, and conversation scopes. These scopes are seamlessly integrated
through JSF variable resolvers and work the same in all JSF
applications.
### 13.4.1. Using Flow Variables
The easiest and most natural way to declare and manage the model
is through the use of [flow
variables](defining-flows.html#flow-variables). You can declare these variables at the beginning of
the flow:
```
```
and then reference this variable in one of the flow's JSF view
templates through EL:
```
```
Note that you do not need to prefix the variable with its scope
when referencing it from the template (though you can do so if you need
to be more specific). As with standard JSF beans, all available scopes
will be searched for a matching variable, so you could change the scope
of the variable in your flow definition without having to modify the EL
expressions that reference it.
You can also define view instance variables that are scoped to the
current view and get cleaned up automatically upon transitioning to
another view. This is quite useful with JSF as views are often
constructed to handle multiple in-page events across many requests
before transitioning to another view.
To define a view instance variable, you can use the`var` element inside a `view-state`definition:
```
```
### 13.4.2. Using Scoped Spring Beans
Though defining autowired flow instance variables provides nice
modularization and readability, occasions may arise where you want to
utilize the other capabilities of the Spring container such as AOP. In
these cases, you can define a bean in your Spring ApplicationContext and
give it a specific web flow scope:
```
```
The major difference with this approach is that the bean will not
be fully initialized until it is first accessed via an EL expression.
This sort of lazy instantiation via EL is quite similar to how JSF
managed beans are typically allocated.
### 13.4.3. Manipulating The Model
The need to initialize the model before view rendering (such as by
loading persistent entities from a database) is quite common, but JSF by
itself does not provide any convenient hooks for such initialization.
The flow definition language provides a natural facility for this
through its [Actions](defining-flows.html#flow-actions) . Spring Web
Flow provides some extra conveniences for converting the outcome of an
action into a JSF-specific data structure. For example:
```
```
This will take the result of the`bookingService.findBookings` method an wrap it in a custom
JSF DataModel so that the list can be used in a standard JSF DataTable
component:
```
Name
#{booking.hotel.name}
Confirmation number
#{booking.id}
Action
```
### 13.4.4. Data Model Implementations
In the example above result-type="dataModel" results in the
wrapping of List\ with custom`DataModel` type. The custom`DataModel` provides extra conveniences such as
being serializable for storage beyond request scope as well as access to
the currently selected row in EL expressions. For example, on postback
from a view where the action event was fired by a component within a
DataTable, you can take action on the selected row's model
instance:
```
```
Spring Web Flow provides two custom DataModel types:`OneSelectionTrackingListDataModel` and`ManySelectionTrackingListDataModel`. As the names
indicate they keep track of one or multiple selected rows. This is done
with the help of a`SelectionTrackingActionListener` listener, which
responds to JSF action events and invokes the appopriate methods on the`SelectinAware` data models to record the currently
clicked row.
To understand how this is configured, keep in mind the`FacesConversionService` registers a`DataModelConverter` against the alias "dataModel"
on startup. When result-type="dataModel" is used in a flow definition it
causes the `DataModelConverter` to be used. The
converter then wraps the given List with an instance of`OneSelectionTrackingListDataModel`. To use the`ManySelectionTrackingListDataModel` you will need
to register your own custom converter.
## 13.5. Handling JSF Events With Spring Web Flow
Spring Web Flow allows you to handle JSF action events in a
decoupled way, requiring no direct dependencies in your Java code on JSF
API's. In fact, these events can often be handled completely in the flow
definiton language without requiring any custom Java action code at all.
This allows for a more agile development process since the artifacts being
manipulated in wiring up events (JSF view templates and SWF flow
definitions) are instantly refreshable without requiring a build and
re-deploy of the whole application.
### 13.5.1. Handling JSF In-page Action Events
A simple but common case in JSF is the need to signal an event
that causes manipulation of the model in some way and then redisplays
the same view to reflect the changed state of the model. The flow
definition language has special support for this in the`transition` element.
A good example of this is a table of paged list results. Suppose
you want to be able to load and display only a portion of a large result
list, and allow the user to page through the results. The initial`view-state` definition to load and display the list would
be:
```
```
You construct a JSF DataTable that displays the current`hotels` list, and then place a "More Results" link below the
table:
```
```
This commandLink signals a "next" event from its action attribute.
You can then handle the event by adding to the `view-state`definition:
```
```
Here you handle the "next" event by incrementing the page count on
the searchCriteria instance. The `on-render` action is then
called again with the updated criteria, which causes the next page of
results to be loaded into the DataModel. The same view is re-rendered
since there was no `to` attribute on the`transition` element, and the changes in the model are
reflected in the view.
### 13.5.2. Handling JSF Action Events
The next logical level beyond in-page events are events that
require navigation to another view, with some manipulation of the model
along the way. Achieving this with pure JSF would require adding a
navigation rule to faces-config.xml and likely some intermediary Java
code in a JSF managed bean (both tasks requiring a re-deploy). With the
flow defintion language, you can handle such a case concisely in one
place in a quite similar way to how in-page events are handled.
Continuing on with our use case of manipulating a paged list of
results, suppose we want each row in the displayed DataTable to contain
a link to a detail page for that row instance. You can add a column to
the table containing the following `commandLink`component:
```
```
This raises the "select" event which you can then handle by adding
another `transition` element to the existing`view-state` :
```
```
Here the "select" event is handled by pushing the currently
selected hotel instance from the DataTable into flow scope, so that it
may be referenced by the "reviewHotel" `view-state` .
### 13.5.3. Performing Model Validation
JSF provides useful facilities for validating input at field-level
before changes are applied to the model, but when you need to then
perform more complex validation at the model-level after the updates
have been applied, you are generally left with having to add more custom
code to your JSF action methods in the managed bean. Validation of this
sort is something that is generally a responsibility of the domain model
itself, but it is difficult to get any error messages propagated back to
the view without introducing an undesirable dependency on the JSF API in
your domain layer.
With Web Flow, you can utilize the generic and low-level`MessageContext` in your business code and any messages added
there will then be available to the `FacesContext` at render
time.
For example, suppose you have a view where the user enters the
necessary details to complete a hotel booking, and you need to ensure
the Check In and Check Out dates adhere to a given set of business
rules. You can invoke such model-level validation from a`transition` element:
```
```
Here the "proceed" event is handled by invoking a model-level
validation method on the booking instance, passing the generic`MessageContext` instance so that messages may be recorded.
The messages can then be displayed along with any other JSF messages
with the `h:messages` component,
### 13.5.4. Handling Ajax Events In JSF
JSF provides built-in support for sending Ajax requests and
performing partial processing and rendering on the server-side. You can
specify a list of id's for partial rendering through the \
facelets tag.
In Spring Web Flow you also have the option to specify the ids to
use for partial rendering on the server side with the render
action:
```
```
## 13.6. Embedding a Flow On a Page
By default when a flow enters a view state, it executes a
client-side redirect before rendering the view. This approach is known as
POST-REDIRECT-GET. It has the advantage of separating the form processing
for one view from the rendering of the next view. As a result the browser
Back and Refresh buttons work seamlessly without causing any browser
warnings.
Normally the client-side redirect is transparent from a user's
perspective. However, there are situations where POST-REDIRECT-GET may not
bring the same benefits. For example sometimes it may be useful to embed
a flow on a page and drive it via Ajax requests refreshing only the area
of the page where the flow is rendered. Not only is it unnecessary to use
client-side redirects in this case, it is also not the desired behavior
with regards to keeping the surrounding content of the page intact.
To indicate a flow should execute in "page embedded" mode all
you need to do is pass an extra flow input attribute called "mode"
with a value of "embedded". Below is an example of a top-level
container flow invoking a sub-flow in an embedded mode:
```
```
When launched in "page embedded" mode the sub-flow will not issue
flow execution redirects during Ajax requests.
If you'd like to see examples of an embedded flow please refer to
the webflow-primefaces-showcase project. You can check out
the source code locally, build it as you would a Maven project, and import
it into Eclipse:
```
cd some-directory
svn co https://src.springframework.org/svn/spring-samples/webflow-primefaces-showcase
cd webflow-primefaces-showcase
mvn package
# import into Eclipse
```
The specific example you need to look at is under the "Advanced Ajax"
tab and is called "Top Flow with Embedded Sub-Flow".
## 13.7. Redirect In Same State
By default Web Flow does a client-side redirect even it it remains in the same view state as long as the current request is not an Ajax request.
This is quite useful after form validation failures for example.
If the user hits Refresh or Back they won't see any browser warnings.
They would if the Web Flow didn't do a redirect.
This can lead to a problem specific to JSF environments where a specific Sun Mojarra listener component caches the FacesContext assuming the same instance is available throughout the JSF lifecycle.
In Web Flow however the render phase is temporarily put on hold and a client-side redirect executed.
The default behavior of Web Flow is desirable and it is unlikely JSF applications will experience the issue.
This is because Ajax is often enabled the default in JSF component libraries and Web Flow does not redirect during Ajax requests.
However if you experience this issue you can disable client-side redirects within the same view as follows:
```
```
## 13.8. Handling File Uploads with JSF
Most JSF component providers include some form of 'file upload' component. Generally when working
with these components JSF must take complete control of parsing multi-part requests and Spring MVC's`MultipartResolver` cannot be used.
Spring Web Flow has been tested with file upload components from PrimeFaces. Check the
documentation of your JSF component library for other providers to see how to configure file upload.
### 13.8.1. File Uploads with PrimeFaces
PrimeFaces provides a `` component for uploading files. In order
to use the component you need to configure the `org.primefaces.webapp.filter.FileUploadFilter`servlet filter. The filter needs to be configured against Spring MVC's`DispatcherServlet` in your `web.xml`:
```
PrimeFaces FileUpload Filterorg.primefaces.webapp.filter.FileUploadFilterPrimeFaces FileUpload FilterSpring MVC Dispatcher Servletprimefaces.UPLOADERcommons
```
For more details refer to the[PrimeFaces documentation](http://primefaces.org/documentation.html).
## 13.9. Using the Spring Security Facelets Tag Library
To use the library you'll need to create a `.taglib.xml`file and register it in `web.xml`.
Create the file`/WEB-INF/springsecurity.taglib.xml` with the following
content:
```
http://www.springframework.org/security/tagsauthorizeorg.springframework.faces.security.FaceletsAuthorizeTagHandlerareAllGrantedorg.springframework.faces.security.FaceletsAuthorizeTagUtilsboolean areAllGranted(java.lang.String)areAnyGrantedorg.springframework.faces.security.FaceletsAuthorizeTagUtilsboolean areAnyGranted(java.lang.String)areNotGrantedorg.springframework.faces.security.FaceletsAuthorizeTagUtilsboolean areNotGranted(java.lang.String)isAllowedorg.springframework.faces.security.FaceletsAuthorizeTagUtilsboolean isAllowed(java.lang.String, java.lang.String)
```
Next, register the above file taglib in web.xml:
```
javax.faces.FACELETS_LIBRARIES/WEB-INF/springsecurity.taglib.xml
```
Now you are ready to use the tag library in your views. You can use
the authorize tag to include nested content conditionally:
```
Lorem ipsum dolor sit amet
Lorem ipsum dolor sit amet
Lorem ipsum dolor sit amet
```
You can also use one of several EL functions in the rendered or
other attribute of any JSF component:
```
```
## 13.10. Third-Party Component Library Integration
The Spring Web Flow JSF integration strives to be compatible with
any third-party JSF component library. By honoring all of the standard
semantics of the JSF specification within the SWF-driven JSF lifecycle,
third-party libraries in general should "just work". The main thing to
remember is that configuration in web.xml will change slightly since Web
Flow requests are not routed through the standard FacesServlet. Typically,
anything that is traditionally mapped to the FacesServlet should be mapped
to the Spring DispatcherServlet instead. (You can also map to both if for
example you are migrating a legacy JSF application page-by-page.).