Q: How does JSF depict the MVC (a.k.a Model View Controller) model?
Ans. The data that is manipulated in form or the other is done by model. The data presented to user in one form or the other is done by view. JSF is connects the view and the model. View can be depicted as shown by:
<h:inputText value="#{user.name}"/>
JSF acts as controller by way of action processing done by the user or triggering of an event. For ex.
<h:commandbutton value="Login" action="login"/>
, this button event will triggered by the user on Button press, which will invoke the login Bean as stated in the faces-config.xml file.
Hence, it could be summarized as below: User Button Click -> form submission to server -> invocation of Bean class -> result thrown by Bean class caught be navigation rule -> navigation rule based on action directs to specific page.
Q: What does it mean by rendering of page in JSF?
Ans. Every JSF page as described has various components made with the help of JSF library. JSF may contain h:form, h:inputText, h:commandButton, etc. Each of these are rendered (translated) to HTML output. This process is called encoding. The encoding procedure also assigns each component with a unique ID assigned by framework. The ID generated is random.
Q: How to show Confirmation Dialog when user Click the Command Link?
A: h:commandLink assign the onclick attribute for internal use. So, you cannot use it to write your own code. This problem will fixed in the JSF 1.2. For the current JSF version you can use onmousedown event that occurs before onclick. <script language="javascript"> function ConfirmDelete(link) { var delete = confirm('Do you want to Delete?'); if (delete == true) { link.onclick(); } } </script> . . . . <h:commandLink action="delete" onmousedown="return ConfirmDelete(this);"> <h:outputText value="delete it"/> </h:commandLink>
Q: What is the different between getRequestParameterMap() and getRequestParameterValuesMap()
getRequestParameterValuesMap() similar to getRequestParameterMap(), but contains multiple values for for the parameters with the same name. It is important if you one of the components such as <h:selectMany>.
Q: Is it possible to have more than one Faces Configuration file?
Yes. You can define the list of the configuration files in the web.xml.
This is an example:
<context-param>
<param-name>javax.faces.CONFIG_FILES</param-name>
<param-value>/WEB-INF/faces-config-navigation.xml,/WEB-INF/faces-beans.xml</param-value>
</context-param>
Note: Do not register /WEB-INF/faces-config.xml file in the web.xml . Otherwise, the JSF implementation will process it twice.
________________________________________
Hi there, I guess the Note: column should have been meant or intended for "faces-config.xml" file as thats the default configuration file for JSF (which is similar to struts-config.xml for Struts!!). faces-context.xml file sounds like the user defined config file similar to the aforementioned two xml files.
Q: How to mask actual URL to the JSF page?
A: You'll need to implement your own version of javax.faces.ViewHandler which does what you need. Then, you register your own view handler in faces-config.xml.
Here's a simple abstract ViewHandler you can extend and then implement the 3 abstract methods for. The abstract methods you override here are where you'll do your conversions to/from URI to physical paths on the file system. This information is just passed right along to the default ViewHandler for JSF to deal with in the usual way. For example, you could override these methods to add and remove the file extension of an incoming view id (like in your example), for extension-less view URIs.
import java.io.IOException;
import java.util.Locale;
import javax.faces.FacesException;
import javax.faces.application.ViewHandler;
import javax.faces.component.UIViewRoot;
import javax.faces.context.FacesContext;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* A facade view handler which maps URIs into actual physical views that the
* underlying implementation can deal with regularly.
*
* Therefore, all internal references to view ids, for example in faces-config,
* will use the path to the physical files. Everything publicized, however, will
* see a "converted" / facade url.
*/
public abstract class SimpleConverterViewHandler extends ViewHandler {
private static final Log LOG = LogFactory
.getLog(SimpleConverterViewHandler.class);
private final ViewHandler base;
public SimpleConverterViewHandler(ViewHandler base) {
this.base = base;
}
/**
* Distinguishes a URI from a physical file view.
*
* Tests if a view id is in the expected format -- the format corresponding
* to the physical file views, as opposed to the URIs.
*
* This test is necessary because JSF takes the view ID from the
* faces-config navigation, and calls renderView() on it, etc.
*/
public abstract boolean isViewFormat(FacesContext context, String viewId);
/**
* Convert a private file path (view id) into a public URI.
*/
public abstract String convertViewToURI(FacesContext context, String viewId);
/**
* Convert a public URI into a private file path (view id)
*
* note: uri always starts with "/";
*/
public abstract String convertURIToView(FacesContext context, String uri);
public String getActionURL(FacesContext context, String viewId) {
// NOTE: this is used for FORM actions.
String newViewId = convertViewToURI(context, viewId);
LOG.debug("getViewIdPath: " + viewId + "->" + newViewId);
return base.getActionURL(context, newViewId);
}
private String doConvertURIToView(FacesContext context, String requestURI) {
if (isViewFormat(context, requestURI)) {
return requestURI;
} else {
return convertURIToView(context, requestURI);
}
}
public void renderView(FacesContext context, UIViewRoot viewToRender)
throws IOException, FacesException {
if (null == context || null == viewToRender)
throw new NullPointerException("null context or view");
String requestURI = viewToRender.getViewId();
String newViewId = doConvertURIToView(context, requestURI);
LOG.debug("renderView: " + requestURI + "->" + newViewId);
viewToRender.setViewId(newViewId);
base.renderView(context, viewToRender);
}
public UIViewRoot restoreView(FacesContext context, String viewId) {
String newViewId = doConvertURIToView(context, viewId);
LOG.debug("restoreView: " + viewId + "->" + newViewId);
return base.restoreView(context, newViewId);
}
public Locale calculateLocale(FacesContext arg0) {
return base.calculateLocale(arg0);
}
public String calculateRenderKitId(FacesContext arg0) {
return base.calculateRenderKitId(arg0);
}
public UIViewRoot createView(FacesContext arg0, String arg1) {
return base.createView(arg0, arg1);
}
public String getResourceURL(FacesContext arg0, String arg1) {
return base.getResourceURL(arg0, arg1);
}
public void writeState(FacesContext arg0) throws IOException {
base.writeState(arg0);
}
}
Ans. The data that is manipulated in form or the other is done by model. The data presented to user in one form or the other is done by view. JSF is connects the view and the model. View can be depicted as shown by:
<h:inputText value="#{user.name}"/>
JSF acts as controller by way of action processing done by the user or triggering of an event. For ex.
<h:commandbutton value="Login" action="login"/>
, this button event will triggered by the user on Button press, which will invoke the login Bean as stated in the faces-config.xml file.
Hence, it could be summarized as below: User Button Click -> form submission to server -> invocation of Bean class -> result thrown by Bean class caught be navigation rule -> navigation rule based on action directs to specific page.
Q: What does it mean by rendering of page in JSF?
Ans. Every JSF page as described has various components made with the help of JSF library. JSF may contain h:form, h:inputText, h:commandButton, etc. Each of these are rendered (translated) to HTML output. This process is called encoding. The encoding procedure also assigns each component with a unique ID assigned by framework. The ID generated is random.
Q: How to show Confirmation Dialog when user Click the Command Link?
A: h:commandLink assign the onclick attribute for internal use. So, you cannot use it to write your own code. This problem will fixed in the JSF 1.2. For the current JSF version you can use onmousedown event that occurs before onclick. <script language="javascript"> function ConfirmDelete(link) { var delete = confirm('Do you want to Delete?'); if (delete == true) { link.onclick(); } } </script> . . . . <h:commandLink action="delete" onmousedown="return ConfirmDelete(this);"> <h:outputText value="delete it"/> </h:commandLink>
Q: What is the different between getRequestParameterMap() and getRequestParameterValuesMap()
getRequestParameterValuesMap() similar to getRequestParameterMap(), but contains multiple values for for the parameters with the same name. It is important if you one of the components such as <h:selectMany>.
Q: Is it possible to have more than one Faces Configuration file?
Yes. You can define the list of the configuration files in the web.xml.
This is an example:
<context-param>
<param-name>javax.faces.CONFIG_FILES</param-name>
<param-value>/WEB-INF/faces-config-navigation.xml,/WEB-INF/faces-beans.xml</param-value>
</context-param>
Note: Do not register /WEB-INF/faces-config.xml file in the web.xml . Otherwise, the JSF implementation will process it twice.
________________________________________
Hi there, I guess the Note: column should have been meant or intended for "faces-config.xml" file as thats the default configuration file for JSF (which is similar to struts-config.xml for Struts!!). faces-context.xml file sounds like the user defined config file similar to the aforementioned two xml files.
Q: How to mask actual URL to the JSF page?
A: You'll need to implement your own version of javax.faces.ViewHandler which does what you need. Then, you register your own view handler in faces-config.xml.
Here's a simple abstract ViewHandler you can extend and then implement the 3 abstract methods for. The abstract methods you override here are where you'll do your conversions to/from URI to physical paths on the file system. This information is just passed right along to the default ViewHandler for JSF to deal with in the usual way. For example, you could override these methods to add and remove the file extension of an incoming view id (like in your example), for extension-less view URIs.
import java.io.IOException;
import java.util.Locale;
import javax.faces.FacesException;
import javax.faces.application.ViewHandler;
import javax.faces.component.UIViewRoot;
import javax.faces.context.FacesContext;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* A facade view handler which maps URIs into actual physical views that the
* underlying implementation can deal with regularly.
*
* Therefore, all internal references to view ids, for example in faces-config,
* will use the path to the physical files. Everything publicized, however, will
* see a "converted" / facade url.
*/
public abstract class SimpleConverterViewHandler extends ViewHandler {
private static final Log LOG = LogFactory
.getLog(SimpleConverterViewHandler.class);
private final ViewHandler base;
public SimpleConverterViewHandler(ViewHandler base) {
this.base = base;
}
/**
* Distinguishes a URI from a physical file view.
*
* Tests if a view id is in the expected format -- the format corresponding
* to the physical file views, as opposed to the URIs.
*
* This test is necessary because JSF takes the view ID from the
* faces-config navigation, and calls renderView() on it, etc.
*/
public abstract boolean isViewFormat(FacesContext context, String viewId);
/**
* Convert a private file path (view id) into a public URI.
*/
public abstract String convertViewToURI(FacesContext context, String viewId);
/**
* Convert a public URI into a private file path (view id)
*
* note: uri always starts with "/";
*/
public abstract String convertURIToView(FacesContext context, String uri);
public String getActionURL(FacesContext context, String viewId) {
// NOTE: this is used for FORM actions.
String newViewId = convertViewToURI(context, viewId);
LOG.debug("getViewIdPath: " + viewId + "->" + newViewId);
return base.getActionURL(context, newViewId);
}
private String doConvertURIToView(FacesContext context, String requestURI) {
if (isViewFormat(context, requestURI)) {
return requestURI;
} else {
return convertURIToView(context, requestURI);
}
}
public void renderView(FacesContext context, UIViewRoot viewToRender)
throws IOException, FacesException {
if (null == context || null == viewToRender)
throw new NullPointerException("null context or view");
String requestURI = viewToRender.getViewId();
String newViewId = doConvertURIToView(context, requestURI);
LOG.debug("renderView: " + requestURI + "->" + newViewId);
viewToRender.setViewId(newViewId);
base.renderView(context, viewToRender);
}
public UIViewRoot restoreView(FacesContext context, String viewId) {
String newViewId = doConvertURIToView(context, viewId);
LOG.debug("restoreView: " + viewId + "->" + newViewId);
return base.restoreView(context, newViewId);
}
public Locale calculateLocale(FacesContext arg0) {
return base.calculateLocale(arg0);
}
public String calculateRenderKitId(FacesContext arg0) {
return base.calculateRenderKitId(arg0);
}
public UIViewRoot createView(FacesContext arg0, String arg1) {
return base.createView(arg0, arg1);
}
public String getResourceURL(FacesContext arg0, String arg1) {
return base.getResourceURL(arg0, arg1);
}
public void writeState(FacesContext arg0) throws IOException {
base.writeState(arg0);
}
}
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