JSF Component state Save process

JSF can save state of component tree in either session or on clients machine inform of serialized data .
While creating component tree JSF creates a key and keep all objects of component tree as UIViewRoot in session with against it.For next JSF request it will use same key to restore that view 🙂
For client side saving has performance issues like it has to serialize whole tree and write it in response ship in form of gzip to client.Next time when same client make JSF request from same page it de-serialize it and inflate all objects in corresponding state .

Setting for state saving is done in web.xml.

Server side state saving is where the component tree and all component state are stored within the user’s session. This entry within the session is tracked by writing a key in the response that is used to lookup the entry on subsequent post-backs.

Client side state saving doesn’t leverage the server side session mechanism at all, instead, the component tree and state will be serialized using Java Serialization, GZIP compressed (at least that is the default), Base64 encoded, and written to the response. When a post-back occurs, the encoding process will be reversed which will result in the tree and state we started with.

Setting in web.xml

  <context-param>
<description>State saving method: 'client' or 'server' (=default). See JSF Specification 2.5.2</description>
<param-name>javax.faces.STATE_SAVING_METHOD</param-name>
<param-value>server</param-value>
</context-param>

Why does JSF need to save the state of UI components on the server side ?

Because HTTP is stateless and JSF is stateful. The JSF component tree is subject to dynamic (programmatic) changes. JSF simply needs to know the exact state as it was when the form had been displayed to the enduser, so that it can successfully process the whole JSF lifecycle based on the information provided by the original JSF component tree when the form has been submitted back to the server. The component tree provides information about the request parameter names, the necessary converters/validators, the bound managed bean properties and action methods.

As a logged-in user on the application navigates though pages, will the state of components keep on accumulating on the server?

Technically, that depends on the implementation. If you’re talking about page-to-page navigation (just GET requests) then Mojarra won’t save anything in session. If they are however POST requests (forms with commandlinks/buttons), then Mojarra will save state of each form in session until the max limit. This enables the enduser to open multiple forms in different browser tabs in the same session.

Or, when the state saving is set to client, then JSF won’t store anything in session. You can do that by the following context param in web.xml:

<context-param>
    <param-name>javax.faces.STATE_SAVING_METHOD</param-name>
    <param-value>client</param-value>
</context-param>

It will then be serialized to an encrypted string in a hidden input field with the name javax.faces.ViewState of the form.

Happy learning with Vinay in techartifact

JSF UTIL class in Oracle ADF

Well i am refering here the jsfutil class for my reference.this code doesn’t written by me.But it is very helpful for ADF developer.

 import java.util.Iterator;
import java.util.Locale;
import java.util.Map;
import java.util.MissingResourceException;
import java.util.ResourceBundle;
import javax.el.ELContext;
import javax.el.ExpressionFactory;
import javax.el.MethodExpression;
import javax.el.ValueExpression;
import javax.faces.application.Application;
import javax.faces.application.FacesMessage;
import javax.faces.component.UIComponent;
import javax.faces.component.UIViewRoot;
import javax.faces.context.ExternalContext;
import javax.faces.context.FacesContext;
import javax.servlet.http.HttpServletRequest;
import oracle.adf.model.binding.DCBindingContainer;
/**
* General useful static utilies for working with JSF.
* NOTE: Updated to use JSF 1.2 ExpressionFactory.
*
*/
public class JSFUtils {
private static final String NO_RESOURCE_FOUND = "Missing resource: ";
/**
* Method for taking a reference to a JSF binding expression and returning
* the matching object (or creating it).
* @param expression EL expression
* @return Managed object
*/
public static Object resolveExpression(String expression) {
FacesContext facesContext = getFacesContext();
Application app = facesContext.getApplication();
ExpressionFactory elFactory = app.getExpressionFactory();
ELContext elContext = facesContext.getELContext();
ValueExpression valueExp =
elFactory.createValueExpression(elContext, expression,
Object.class);
return valueExp.getValue(elContext);
}
public static String resolveRemoteUser() {
FacesContext facesContext = getFacesContext();
ExternalContext ectx = facesContext.getExternalContext();
return ectx.getRemoteUser();
}
public static String resolveUserPrincipal() {
FacesContext facesContext = getFacesContext();
ExternalContext ectx = facesContext.getExternalContext();
HttpServletRequest request = (HttpServletRequest)ectx.getRequest();
return request.getUserPrincipal().getName();
}
public static Object resloveMethodExpression(String expression,
Class returnType,
Class[] argTypes,
Object[] argValues) {
FacesContext facesContext = getFacesContext();
Application app = facesContext.getApplication();
ExpressionFactory elFactory = app.getExpressionFactory();
ELContext elContext = facesContext.getELContext();
MethodExpression methodExpression =
elFactory.createMethodExpression(elContext, expression, returnType,
argTypes);
return methodExpression.invoke(elContext, argValues);
}
/**
* Method for taking a reference to a JSF binding expression and returning
* the matching Boolean.
* @param expression EL expression
* @return Managed object
*/
public static Boolean resolveExpressionAsBoolean(String expression) {
return (Boolean)resolveExpression(expression);
}
/**
* Method for taking a reference to a JSF binding expression and returning
* the matching String (or creating it).
* @param expression EL expression
* @return Managed object
*/
public static String resolveExpressionAsString(String expression) {
return (String)resolveExpression(expression);
}
/**
* Convenience method for resolving a reference to a managed bean by name
* rather than by expression.
* @param beanName name of managed bean
* @return Managed object
*/
public static Object getManagedBeanValue(String beanName) {
StringBuffer buff = new StringBuffer("#{");
buff.append(beanName);
buff.append("}");
return resolveExpression(buff.toString());
}
/**
* Method for setting a new object into a JSF managed bean
* Note: will fail silently if the supplied object does
* not match the type of the managed bean.
* @param expression EL expression
* @param newValue new value to set
*/
public static void setExpressionValue(String expression, Object newValue) {
FacesContext facesContext = getFacesContext();
Application app = facesContext.getApplication();
ExpressionFactory elFactory = app.getExpressionFactory();
ELContext elContext = facesContext.getELContext();
ValueExpression valueExp =
elFactory.createValueExpression(elContext, expression,
Object.class);
//Check that the input newValue can be cast to the property type
//expected by the managed bean.
//If the managed Bean expects a primitive we rely on Auto-Unboxing
Class bindClass = valueExp.getType(elContext);
if (bindClass.isPrimitive() || bindClass.isInstance(newValue)) {
valueExp.setValue(elContext, newValue);
}
}
/**
* Convenience method for setting the value of a managed bean by name
* rather than by expression.
* @param beanName name of managed bean
* @param newValue new value to set
*/
public static void setManagedBeanValue(String beanName, Object newValue) {
StringBuffer buff = new StringBuffer("#{");
buff.append(beanName);
buff.append("}");
setExpressionValue(buff.toString(), newValue);
}
/**
* Convenience method for setting Session variables.
* @param key object key
* @param object value to store
*/
public static void storeOnSession(String key, Object object) {
FacesContext ctx = getFacesContext();
Map sessionState = ctx.getExternalContext().getSessionMap();
sessionState.put(key, object);
}
/**
* Convenience method for getting Session variables.
* @param key object key
* @return session object for key
*/
public static Object getFromSession(String key) {
FacesContext ctx = getFacesContext();
Map sessionState = ctx.getExternalContext().getSessionMap();
return sessionState.get(key);
}
public static String getFromHeader(String key) {
FacesContext ctx = getFacesContext();
ExternalContext ectx = ctx.getExternalContext();
return ectx.getRequestHeaderMap().get(key);
}
/**
* Convenience method for getting Request variables.
* @param key object key
* @return session object for key
*/
public static Object getFromRequest(String key) {
FacesContext ctx = getFacesContext();
Map sessionState = ctx.getExternalContext().getRequestMap();
return sessionState.get(key);
}
/**
* Pulls a String resource from the property bundle that
* is defined under the application <message-bundle> element in
* the faces config. Respects Locale
* @param key string message key
* @return Resource value or placeholder error String
*/
public static String getStringFromBundle(String key) {
ResourceBundle bundle = getBundle();
return getStringSafely(bundle, key, null);
}
/**
* Convenience method to construct a FacesMesssage
* from a defined error key and severity
* This assumes that the error keys follow the convention of
* using _detail for the detailed part of the
* message, otherwise the main message is returned for the
* detail as well.
* @param key for the error message in the resource bundle
* @param severity severity of message
* @return Faces Message object
*/
public static FacesMessage getMessageFromBundle(String key,
FacesMessage.Severity severity) {
ResourceBundle bundle = getBundle();
String summary = getStringSafely(bundle, key, null);
String detail = getStringSafely(bundle, key + "_detail", summary);
FacesMessage message = new FacesMessage(summary, detail);
message.setSeverity(severity);
return message;
}
/**
* Add JSF info message.
* @param msg info message string
*/
public static void addFacesInformationMessage(String msg) {
FacesContext ctx = getFacesContext();
FacesMessage fm =
new FacesMessage(FacesMessage.SEVERITY_INFO, msg, "");
ctx.addMessage(getRootViewComponentId(), fm);
}
/**
* Add JSF error message.
* @param msg error message string
*/
public static void addFacesErrorMessage(String msg) {
FacesContext ctx = getFacesContext();
FacesMessage fm =
new FacesMessage(FacesMessage.SEVERITY_ERROR, msg, "");
ctx.addMessage(getRootViewComponentId(), fm);
}
/**
* Add JSF error message for a specific attribute.
* @param attrName name of attribute
* @param msg error message string
*/
public static void addFacesErrorMessage(String attrName, String msg) {
FacesContext ctx = getFacesContext();
FacesMessage fm =
new FacesMessage(FacesMessage.SEVERITY_ERROR, attrName, msg);
ctx.addMessage(getRootViewComponentId(), fm);
}
// Informational getters
/**
* Get view id of the view root.
* @return view id of the view root
*/
public static String getRootViewId() {
return getFacesContext().getViewRoot().getViewId();
}
/**
* Get component id of the view root.
* @return component id of the view root
*/
public static String getRootViewComponentId() {
return getFacesContext().getViewRoot().getId();
}
/**
* Get FacesContext.
* @return FacesContext
*/
public static FacesContext getFacesContext() {
return FacesContext.getCurrentInstance();
}
/*
* Internal method to pull out the correct local
* message bundle
*/
private static ResourceBundle getBundle() {
FacesContext ctx = getFacesContext();
UIViewRoot uiRoot = ctx.getViewRoot();
Locale locale = uiRoot.getLocale();
ClassLoader ldr = Thread.currentThread().getContextClassLoader();
return ResourceBundle.getBundle(ctx.getApplication().getMessageBundle(),
locale, ldr);
}
/**
* Get an HTTP Request attribute.
* @param name attribute name
* @return attribute value
*/
public static Object getRequestAttribute(String name) {
return getFacesContext().getExternalContext().getRequestMap().get(name);
}
/**
* Set an HTTP Request attribute.
* @param name attribute name
* @param value attribute value
*/
public static void setRequestAttribute(String name, Object value) {
getFacesContext().getExternalContext().getRequestMap().put(name,
value);
}
/*
* Internal method to proxy for resource keys that don't exist
*/
private static String getStringSafely(ResourceBundle bundle, String key,
String defaultValue) {
String resource = null;
try {
resource = bundle.getString(key);
} catch (MissingResourceException mrex) {
if (defaultValue != null) {
resource = defaultValue;
} else {
resource = NO_RESOURCE_FOUND + key;
}
}
return resource;
}
/**
* Locate an UIComponent in view root with its component id. Use a recursive way to achieve this.
* @param id UIComponent id
* @return UIComponent object
*/
public static UIComponent findComponentInRoot(String id) {
UIComponent component = null;
FacesContext facesContext = FacesContext.getCurrentInstance();
if (facesContext != null) {
UIComponent root = facesContext.getViewRoot();
component = findComponent(root, id);
}
return component;
}
/**
* Locate an UIComponent from its root component.
* Taken from http://www.jroller.com/page/mert?entry=how_to_find_a_uicomponent
* @param base root Component (parent)
* @param id UIComponent id
* @return UIComponent object
*/
public static UIComponent findComponent(UIComponent base, String id) {
if (id.equals(base.getId()))
return base;
UIComponent children = null;
UIComponent result = null;
Iterator childrens = base.getFacetsAndChildren();
while (childrens.hasNext() && (result == null)) {
children = (UIComponent)childrens.next();
if (id.equals(children.getId())) {
result = children;
break;
}
result = findComponent(children, id);
if (result != null) {
break;
}
}
return result;
}
/**
* Method to create a redirect URL. The assumption is that the JSF servlet mapping is
* "faces", which is the default
*
* @param view the JSP or JSPX page to redirect to
* @return a URL to redirect to
*/
public static String getPageURL(String view) {
FacesContext facesContext = getFacesContext();
ExternalContext externalContext = facesContext.getExternalContext();
String url =
((HttpServletRequest)externalContext.getRequest()).getRequestURL().toString();
StringBuffer newUrlBuffer = new StringBuffer();
newUrlBuffer.append(url.substring(0, url.lastIndexOf("faces/")));
newUrlBuffer.append("faces");
String targetPageUrl = view.startsWith("/") ? view : "/" + view;
newUrlBuffer.append(targetPageUrl);
return newUrlBuffer.toString();
}

// Get the error


String error = iterBind.getError().getMessage();













// Get a session bean

FacesContext ctx = FacesContext.getCurrentInstance();

ExpressionFactory ef = ctx.getApplication().getExpressionFactory();

ValueExpression ve = ef.createValueExpression(ctx.getELContext(), "#{testSessionBean}", TestSession.class);

TestSession test = (TestSession)ve.getValue(ctx.getELContext());



// main jsf page

DCBindingContainer dc = (DCBindingContainer)BindingContext.getCurrent().getCurrentBindingsEntry();

// taskflow binding

DCTaskFlowBinding tf = (DCTaskFlowBinding)dc.findExecutableBinding("dynamicRegion1");

// pagedef of a page fragment

JUFormBinding form = (JUFormBinding) tf.findExecutableBinding("regions_employee_regionPageDef");

// handle to binding container of the region.

DCBindingContainer dcRegion = form;







// return a methodexpression like a control flow case action or ADF pagedef action

private MethodExpression getMethodExpression(String name) {

Class [] argtypes = new Class[1];

argtypes[0] = ActionEvent.class;

FacesContext facesCtx = FacesContext.getCurrentInstance();

Application app = facesCtx.getApplication();

ExpressionFactory elFactory = app.getExpressionFactory();

ELContext elContext = facesCtx.getELContext();

return elFactory.createMethodExpression(elContext,name,null,argtypes);

}



//

RichCommandMenuItem menuPage1 = new RichCommandMenuItem();

menuPage1.setId("page1");

menuPage1.setText("Page 1");

menuPage1.setActionExpression(getMethodExpression("page1"));



RichCommandButton button = new RichCommandButton();

button.setValueExpression("disabled",getValueExpression("#{!bindings."+item+".enabled}"));

button.setId(item);

button.setText(item);

MethodExpression me = getMethodExpression("#{bindings."+item+".execute}");

button.addActionListener(new MethodExpressionActionListener(me));

footer.getChildren().add(button);





// get a value

private ValueExpression getValueExpression(String name) {

FacesContext facesCtx = FacesContext.getCurrentInstance();

Application app = facesCtx.getApplication();

ExpressionFactory elFactory = app.getExpressionFactory();

ELContext elContext = facesCtx.getELContext();

return elFactory.createValueExpression(elContext, name, Object.class);

}

// an example how to use this

RichInputText input = new RichInputText();

input.setValueExpression("value",getValueExpression("#{bindings."+item+".inputValue}"));

input.setValueExpression("label",getValueExpression("#{bindings."+item+".hints.label}"));

input.setId(item);

panelForm.getChildren().add(input);

// find a jsf component

private UIComponent getUIComponent(String name) {

FacesContext facesCtx = FacesContext.getCurrentInstance();

return facesCtx.getViewRoot().findComponent(name) ;

}

// change the locale

Locale newLocale = new Locale(this.language);

FacesContext context = FacesContext.getCurrentInstance();

context.getViewRoot().setLocale(newLocale);
} 


Happy coding with Vinay in Techartifact.