we're delevoping a JSF application with MyFaces 2.1.
For reloading xhtml on-the-fly, we set
<context-param>
<param-name>javax.faces.FACELETS_REFRESH_PERIOD</param-name>
<param-value>0</param-value>
</context-param>
This works fine, but slows down the application (about times 5 compared to value -1. For production it's set to -1 of course).
This makes me wondering if there's any way to change this parameter on demand. Thus I could set it to -1 and create something like a servlet in order to trigger the xhtml reload.
Is something like this possible or has anyone an idea for refreshing xhtml on demand?
Thanks a lot!
Related
I have some Facelets files like below.
WebContent
|-- index.xhtml
|-- register.xhtml
|-- templates
| |--userForm.xhtml
| `--banner.xhtml
:
Both pages are using templates from /templates directory. My /index.xhtml opens fine in browser. I get the generated HTML output. I have a link in /index.xhtml file to /register.xhtml file.
However, my /register.xhtml is not getting parsed and returns as plain XHTML / raw XML instead of its generated HTML output. All EL expressions in form of #{...} are displayed as-is instead of that their results are being printed. When I rightclick page in browser and do View page source, then I still see the original XHTML source code instead of the generated HTML output. For example, the <h:body> did not become a <body>. It looks like that the template is not being executed.
However, when I open the /register.xhtml like /faces/register.xhtml in browser's address bar, then it displays correctly. How is this caused and how can I solve it?
There are three main causes.
FacesServlet is not invoked.
XML namespace URIs are missing or wrong.
Multiple JSF implemenations have been loaded.
1. Make sure that URL matches FacesServlet mapping
The URL of the link (the URL as you see in browser's address bar) has to match the <url-pattern> of the FacesServlet as definied in web.xml in order to get all the JSF works to run. The FacesServlet is the one responsible for parsing the XHTML file, collecting submitted form values, performing conversion/validation, updating models, invoking actions and generating HTML output. If you don't invoke the FacesServlet by URL, then all you would get (and see via rightclick, View Source in browser) is indeed the raw XHTML source code.
If the <url-pattern> is for example *.jsf, then the link should point to /register.jsf and not /register.xhtml. If it's for example /faces/*, like you have, then the link should point to /faces/register.xhtml and not /register.xhtml. One way to avoid this confusion is to just change the <url-pattern> from /faces/* to *.xhtml. The below is thus the ideal mapping:
<servlet>
<servlet-name>facesServlet</servlet-name>
<servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>facesServlet</servlet-name>
<url-pattern>*.xhtml</url-pattern>
</servlet-mapping>
If you can't change the <url-pattern> to *.xhtml for some reason, then you probably would also like to prevent endusers from directly accessing XHTML source code files by URL. In that case you can add a <security-constraint> on the <url-pattern> of *.xhtml with an empty <auth-constraint> in web.xml which prevents that:
<security-constraint>
<display-name>Restrict direct access to XHTML files</display-name>
<web-resource-collection>
<web-resource-name>XHTML files</web-resource-name>
<url-pattern>*.xhtml</url-pattern>
</web-resource-collection>
<auth-constraint />
</security-constraint>
JSF 2.3 which was introduced April 2017 has already solved all of above by automatically registering the FacesServlet on an URL pattern of *.xhtml during webapp's startup. The alternative is thus to simply upgrade to latest available JSF version which should be JSF 2.3 or higher. But ideally you should still explicitly register the FacesServlet on only one URL pattern of *.xhtml because having multiple possible URLs for exactly the same resource like /register.xhtml, /register.jsf, /register.faces and /faces/register.xhtml is bad for SEO.
See also:
Set default home page via <welcome-file> in JSF project
Opening JSF Facelets page shows "This XML file does not appear to have any style information associated with it."
Sometimes I see JSF URL is *.jsf, sometimes *.xhtml and sometimes /faces/*. Why?
JavaServer Faces 2.2 and HTML5 support, why is XHTML still being used
Which XHTML files do I need to put in /WEB-INF and which not?
Our servlets wiki - to learn the mandatory basics about servlets
2. Make sure that XML namespaces match JSF version
Since introduction of JSF 2.2, another probable cause is that XML namespaces don't match the JSF version. The xmlns.jcp.org like below is new since JSF 2.2 and does not work in older JSF versions. The symptoms are almost the same as if the FacesServlet is not invoked.
<html lang="en"
xmlns="http://www.w3.org/1999/xhtml"
xmlns:f="http://xmlns.jcp.org/jsf/core"
xmlns:h="http://xmlns.jcp.org/jsf/html"
xmlns:ui="http://xmlns.jcp.org/jsf/facelets">
If you can't upgrade to JSF 2.2 or higher, then you need to use the old java.sun.com XML namespaces instead:
<html lang="en"
xmlns="http://www.w3.org/1999/xhtml"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:ui="http://java.sun.com/jsf/facelets">
But ideally you should always use the latest version where available.
See also:
Which XML namespace to use with JSF 2.2 and up
JSF tags not executed
Warning: This page calls for XML namespace http://xmlns.jcp.org/jsf/XXX declared with prefix XXX but no taglibrary exists for that namespace
3. Multiple JSF implementations have been loaded
One more probable cause is that multiple JSF implementations have been loaded by your webapp, conflicting and corrupting each other. For example, when your webapp's runtime classpath is polluted with multiple different versioned JSF libraries, or in the specific Mojarra 2.x + Tomcat 8.x combination, when there's an unnecessary ConfigureListener entry in webapp's web.xml causing it to be loaded twice.
<!-- You MUST remove this one from web.xml! -->
<!-- This is actually a workaround for buggy GlassFish3 and Jetty servers. -->
<!-- When leaving this in and you're targeting Tomcat, you'll run into trouble. -->
<listener>
<listener-class>com.sun.faces.config.ConfigureListener</listener-class>
</listener>
When using Maven, make absolutely sure that you declare the dependencies the right way and that you understand dependency scopes. Importantingly, do not bundle dependencies in webapp when those are already provided by the target server.
See also:
Configuration of com.sun.faces.config.ConfigureListener
How to properly install and configure JSF libraries via Maven?
Make sure that you learn JSF the right way
JSF has a very steep learning curve for those unfamiliar with basic HTTP, HTML and Servlets. There are a lot of low quality resources on the Internet. Please ignore code snippet scraping sites maintained by amateurs with primary focus on advertisement income instead of on teaching, such as roseindia, tutorialspoint, javabeat, baeldung, etc. They are easily recognizable by disturbing advertising links/banners. Also please ignore resources dealing with jurassic JSF 1.x. They are easily recognizable by using JSP files instead of XHTML files. JSP as view technology was deprecated since JSF 2.0 at 2009 already.
To get started the right way, start at our JSF wiki page and order an authoritative book.
See also:
Java / Jakarta EE web development, where do I start and what skills do I need?
What is the need of JSF, when UI can be achieved with JavaScript libraries such as jQuery and AngularJS
I have some Facelets files like below.
WebContent
|-- index.xhtml
|-- register.xhtml
|-- templates
| |--userForm.xhtml
| `--banner.xhtml
:
Both pages are using templates from /templates directory. My /index.xhtml opens fine in browser. I get the generated HTML output. I have a link in /index.xhtml file to /register.xhtml file.
However, my /register.xhtml is not getting parsed and returns as plain XHTML / raw XML instead of its generated HTML output. All EL expressions in form of #{...} are displayed as-is instead of that their results are being printed. When I rightclick page in browser and do View page source, then I still see the original XHTML source code instead of the generated HTML output. For example, the <h:body> did not become a <body>. It looks like that the template is not being executed.
However, when I open the /register.xhtml like /faces/register.xhtml in browser's address bar, then it displays correctly. How is this caused and how can I solve it?
There are three main causes.
FacesServlet is not invoked.
XML namespace URIs are missing or wrong.
Multiple JSF implemenations have been loaded.
1. Make sure that URL matches FacesServlet mapping
The URL of the link (the URL as you see in browser's address bar) has to match the <url-pattern> of the FacesServlet as definied in web.xml in order to get all the JSF works to run. The FacesServlet is the one responsible for parsing the XHTML file, collecting submitted form values, performing conversion/validation, updating models, invoking actions and generating HTML output. If you don't invoke the FacesServlet by URL, then all you would get (and see via rightclick, View Source in browser) is indeed the raw XHTML source code.
If the <url-pattern> is for example *.jsf, then the link should point to /register.jsf and not /register.xhtml. If it's for example /faces/*, like you have, then the link should point to /faces/register.xhtml and not /register.xhtml. One way to avoid this confusion is to just change the <url-pattern> from /faces/* to *.xhtml. The below is thus the ideal mapping:
<servlet>
<servlet-name>facesServlet</servlet-name>
<servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>facesServlet</servlet-name>
<url-pattern>*.xhtml</url-pattern>
</servlet-mapping>
If you can't change the <url-pattern> to *.xhtml for some reason, then you probably would also like to prevent endusers from directly accessing XHTML source code files by URL. In that case you can add a <security-constraint> on the <url-pattern> of *.xhtml with an empty <auth-constraint> in web.xml which prevents that:
<security-constraint>
<display-name>Restrict direct access to XHTML files</display-name>
<web-resource-collection>
<web-resource-name>XHTML files</web-resource-name>
<url-pattern>*.xhtml</url-pattern>
</web-resource-collection>
<auth-constraint />
</security-constraint>
JSF 2.3 which was introduced April 2017 has already solved all of above by automatically registering the FacesServlet on an URL pattern of *.xhtml during webapp's startup. The alternative is thus to simply upgrade to latest available JSF version which should be JSF 2.3 or higher. But ideally you should still explicitly register the FacesServlet on only one URL pattern of *.xhtml because having multiple possible URLs for exactly the same resource like /register.xhtml, /register.jsf, /register.faces and /faces/register.xhtml is bad for SEO.
See also:
Set default home page via <welcome-file> in JSF project
Opening JSF Facelets page shows "This XML file does not appear to have any style information associated with it."
Sometimes I see JSF URL is *.jsf, sometimes *.xhtml and sometimes /faces/*. Why?
JavaServer Faces 2.2 and HTML5 support, why is XHTML still being used
Which XHTML files do I need to put in /WEB-INF and which not?
Our servlets wiki - to learn the mandatory basics about servlets
2. Make sure that XML namespaces match JSF version
Since introduction of JSF 2.2, another probable cause is that XML namespaces don't match the JSF version. The xmlns.jcp.org like below is new since JSF 2.2 and does not work in older JSF versions. The symptoms are almost the same as if the FacesServlet is not invoked.
<html lang="en"
xmlns="http://www.w3.org/1999/xhtml"
xmlns:f="http://xmlns.jcp.org/jsf/core"
xmlns:h="http://xmlns.jcp.org/jsf/html"
xmlns:ui="http://xmlns.jcp.org/jsf/facelets">
If you can't upgrade to JSF 2.2 or higher, then you need to use the old java.sun.com XML namespaces instead:
<html lang="en"
xmlns="http://www.w3.org/1999/xhtml"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:ui="http://java.sun.com/jsf/facelets">
But ideally you should always use the latest version where available.
See also:
Which XML namespace to use with JSF 2.2 and up
JSF tags not executed
Warning: This page calls for XML namespace http://xmlns.jcp.org/jsf/XXX declared with prefix XXX but no taglibrary exists for that namespace
3. Multiple JSF implementations have been loaded
One more probable cause is that multiple JSF implementations have been loaded by your webapp, conflicting and corrupting each other. For example, when your webapp's runtime classpath is polluted with multiple different versioned JSF libraries, or in the specific Mojarra 2.x + Tomcat 8.x combination, when there's an unnecessary ConfigureListener entry in webapp's web.xml causing it to be loaded twice.
<!-- You MUST remove this one from web.xml! -->
<!-- This is actually a workaround for buggy GlassFish3 and Jetty servers. -->
<!-- When leaving this in and you're targeting Tomcat, you'll run into trouble. -->
<listener>
<listener-class>com.sun.faces.config.ConfigureListener</listener-class>
</listener>
When using Maven, make absolutely sure that you declare the dependencies the right way and that you understand dependency scopes. Importantingly, do not bundle dependencies in webapp when those are already provided by the target server.
See also:
Configuration of com.sun.faces.config.ConfigureListener
How to properly install and configure JSF libraries via Maven?
Make sure that you learn JSF the right way
JSF has a very steep learning curve for those unfamiliar with basic HTTP, HTML and Servlets. There are a lot of low quality resources on the Internet. Please ignore code snippet scraping sites maintained by amateurs with primary focus on advertisement income instead of on teaching, such as roseindia, tutorialspoint, javabeat, baeldung, etc. They are easily recognizable by disturbing advertising links/banners. Also please ignore resources dealing with jurassic JSF 1.x. They are easily recognizable by using JSP files instead of XHTML files. JSP as view technology was deprecated since JSF 2.0 at 2009 already.
To get started the right way, start at our JSF wiki page and order an authoritative book.
See also:
Java / Jakarta EE web development, where do I start and what skills do I need?
What is the need of JSF, when UI can be achieved with JavaScript libraries such as jQuery and AngularJS
I have some Facelets files like below.
WebContent
|-- index.xhtml
|-- register.xhtml
|-- templates
| |--userForm.xhtml
| `--banner.xhtml
:
Both pages are using templates from /templates directory. My /index.xhtml opens fine in browser. I get the generated HTML output. I have a link in /index.xhtml file to /register.xhtml file.
However, my /register.xhtml is not getting parsed and returns as plain XHTML / raw XML instead of its generated HTML output. All EL expressions in form of #{...} are displayed as-is instead of that their results are being printed. When I rightclick page in browser and do View page source, then I still see the original XHTML source code instead of the generated HTML output. For example, the <h:body> did not become a <body>. It looks like that the template is not being executed.
However, when I open the /register.xhtml like /faces/register.xhtml in browser's address bar, then it displays correctly. How is this caused and how can I solve it?
There are three main causes.
FacesServlet is not invoked.
XML namespace URIs are missing or wrong.
Multiple JSF implemenations have been loaded.
1. Make sure that URL matches FacesServlet mapping
The URL of the link (the URL as you see in browser's address bar) has to match the <url-pattern> of the FacesServlet as definied in web.xml in order to get all the JSF works to run. The FacesServlet is the one responsible for parsing the XHTML file, collecting submitted form values, performing conversion/validation, updating models, invoking actions and generating HTML output. If you don't invoke the FacesServlet by URL, then all you would get (and see via rightclick, View Source in browser) is indeed the raw XHTML source code.
If the <url-pattern> is for example *.jsf, then the link should point to /register.jsf and not /register.xhtml. If it's for example /faces/*, like you have, then the link should point to /faces/register.xhtml and not /register.xhtml. One way to avoid this confusion is to just change the <url-pattern> from /faces/* to *.xhtml. The below is thus the ideal mapping:
<servlet>
<servlet-name>facesServlet</servlet-name>
<servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>facesServlet</servlet-name>
<url-pattern>*.xhtml</url-pattern>
</servlet-mapping>
If you can't change the <url-pattern> to *.xhtml for some reason, then you probably would also like to prevent endusers from directly accessing XHTML source code files by URL. In that case you can add a <security-constraint> on the <url-pattern> of *.xhtml with an empty <auth-constraint> in web.xml which prevents that:
<security-constraint>
<display-name>Restrict direct access to XHTML files</display-name>
<web-resource-collection>
<web-resource-name>XHTML files</web-resource-name>
<url-pattern>*.xhtml</url-pattern>
</web-resource-collection>
<auth-constraint />
</security-constraint>
JSF 2.3 which was introduced April 2017 has already solved all of above by automatically registering the FacesServlet on an URL pattern of *.xhtml during webapp's startup. The alternative is thus to simply upgrade to latest available JSF version which should be JSF 2.3 or higher. But ideally you should still explicitly register the FacesServlet on only one URL pattern of *.xhtml because having multiple possible URLs for exactly the same resource like /register.xhtml, /register.jsf, /register.faces and /faces/register.xhtml is bad for SEO.
See also:
Set default home page via <welcome-file> in JSF project
Opening JSF Facelets page shows "This XML file does not appear to have any style information associated with it."
Sometimes I see JSF URL is *.jsf, sometimes *.xhtml and sometimes /faces/*. Why?
JavaServer Faces 2.2 and HTML5 support, why is XHTML still being used
Which XHTML files do I need to put in /WEB-INF and which not?
Our servlets wiki - to learn the mandatory basics about servlets
2. Make sure that XML namespaces match JSF version
Since introduction of JSF 2.2, another probable cause is that XML namespaces don't match the JSF version. The xmlns.jcp.org like below is new since JSF 2.2 and does not work in older JSF versions. The symptoms are almost the same as if the FacesServlet is not invoked.
<html lang="en"
xmlns="http://www.w3.org/1999/xhtml"
xmlns:f="http://xmlns.jcp.org/jsf/core"
xmlns:h="http://xmlns.jcp.org/jsf/html"
xmlns:ui="http://xmlns.jcp.org/jsf/facelets">
If you can't upgrade to JSF 2.2 or higher, then you need to use the old java.sun.com XML namespaces instead:
<html lang="en"
xmlns="http://www.w3.org/1999/xhtml"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:ui="http://java.sun.com/jsf/facelets">
But ideally you should always use the latest version where available.
See also:
Which XML namespace to use with JSF 2.2 and up
JSF tags not executed
Warning: This page calls for XML namespace http://xmlns.jcp.org/jsf/XXX declared with prefix XXX but no taglibrary exists for that namespace
3. Multiple JSF implementations have been loaded
One more probable cause is that multiple JSF implementations have been loaded by your webapp, conflicting and corrupting each other. For example, when your webapp's runtime classpath is polluted with multiple different versioned JSF libraries, or in the specific Mojarra 2.x + Tomcat 8.x combination, when there's an unnecessary ConfigureListener entry in webapp's web.xml causing it to be loaded twice.
<!-- You MUST remove this one from web.xml! -->
<!-- This is actually a workaround for buggy GlassFish3 and Jetty servers. -->
<!-- When leaving this in and you're targeting Tomcat, you'll run into trouble. -->
<listener>
<listener-class>com.sun.faces.config.ConfigureListener</listener-class>
</listener>
When using Maven, make absolutely sure that you declare the dependencies the right way and that you understand dependency scopes. Importantingly, do not bundle dependencies in webapp when those are already provided by the target server.
See also:
Configuration of com.sun.faces.config.ConfigureListener
How to properly install and configure JSF libraries via Maven?
Make sure that you learn JSF the right way
JSF has a very steep learning curve for those unfamiliar with basic HTTP, HTML and Servlets. There are a lot of low quality resources on the Internet. Please ignore code snippet scraping sites maintained by amateurs with primary focus on advertisement income instead of on teaching, such as roseindia, tutorialspoint, javabeat, baeldung, etc. They are easily recognizable by disturbing advertising links/banners. Also please ignore resources dealing with jurassic JSF 1.x. They are easily recognizable by using JSP files instead of XHTML files. JSP as view technology was deprecated since JSF 2.0 at 2009 already.
To get started the right way, start at our JSF wiki page and order an authoritative book.
See also:
Java / Jakarta EE web development, where do I start and what skills do I need?
What is the need of JSF, when UI can be achieved with JavaScript libraries such as jQuery and AngularJS
I have some Facelets files like below.
WebContent
|-- index.xhtml
|-- register.xhtml
|-- templates
| |--userForm.xhtml
| `--banner.xhtml
:
Both pages are using templates from /templates directory. My /index.xhtml opens fine in browser. I get the generated HTML output. I have a link in /index.xhtml file to /register.xhtml file.
However, my /register.xhtml is not getting parsed and returns as plain XHTML / raw XML instead of its generated HTML output. All EL expressions in form of #{...} are displayed as-is instead of that their results are being printed. When I rightclick page in browser and do View page source, then I still see the original XHTML source code instead of the generated HTML output. For example, the <h:body> did not become a <body>. It looks like that the template is not being executed.
However, when I open the /register.xhtml like /faces/register.xhtml in browser's address bar, then it displays correctly. How is this caused and how can I solve it?
There are three main causes.
FacesServlet is not invoked.
XML namespace URIs are missing or wrong.
Multiple JSF implemenations have been loaded.
1. Make sure that URL matches FacesServlet mapping
The URL of the link (the URL as you see in browser's address bar) has to match the <url-pattern> of the FacesServlet as definied in web.xml in order to get all the JSF works to run. The FacesServlet is the one responsible for parsing the XHTML file, collecting submitted form values, performing conversion/validation, updating models, invoking actions and generating HTML output. If you don't invoke the FacesServlet by URL, then all you would get (and see via rightclick, View Source in browser) is indeed the raw XHTML source code.
If the <url-pattern> is for example *.jsf, then the link should point to /register.jsf and not /register.xhtml. If it's for example /faces/*, like you have, then the link should point to /faces/register.xhtml and not /register.xhtml. One way to avoid this confusion is to just change the <url-pattern> from /faces/* to *.xhtml. The below is thus the ideal mapping:
<servlet>
<servlet-name>facesServlet</servlet-name>
<servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>facesServlet</servlet-name>
<url-pattern>*.xhtml</url-pattern>
</servlet-mapping>
If you can't change the <url-pattern> to *.xhtml for some reason, then you probably would also like to prevent endusers from directly accessing XHTML source code files by URL. In that case you can add a <security-constraint> on the <url-pattern> of *.xhtml with an empty <auth-constraint> in web.xml which prevents that:
<security-constraint>
<display-name>Restrict direct access to XHTML files</display-name>
<web-resource-collection>
<web-resource-name>XHTML files</web-resource-name>
<url-pattern>*.xhtml</url-pattern>
</web-resource-collection>
<auth-constraint />
</security-constraint>
JSF 2.3 which was introduced April 2017 has already solved all of above by automatically registering the FacesServlet on an URL pattern of *.xhtml during webapp's startup. The alternative is thus to simply upgrade to latest available JSF version which should be JSF 2.3 or higher. But ideally you should still explicitly register the FacesServlet on only one URL pattern of *.xhtml because having multiple possible URLs for exactly the same resource like /register.xhtml, /register.jsf, /register.faces and /faces/register.xhtml is bad for SEO.
See also:
Set default home page via <welcome-file> in JSF project
Opening JSF Facelets page shows "This XML file does not appear to have any style information associated with it."
Sometimes I see JSF URL is *.jsf, sometimes *.xhtml and sometimes /faces/*. Why?
JavaServer Faces 2.2 and HTML5 support, why is XHTML still being used
Which XHTML files do I need to put in /WEB-INF and which not?
Our servlets wiki - to learn the mandatory basics about servlets
2. Make sure that XML namespaces match JSF version
Since introduction of JSF 2.2, another probable cause is that XML namespaces don't match the JSF version. The xmlns.jcp.org like below is new since JSF 2.2 and does not work in older JSF versions. The symptoms are almost the same as if the FacesServlet is not invoked.
<html lang="en"
xmlns="http://www.w3.org/1999/xhtml"
xmlns:f="http://xmlns.jcp.org/jsf/core"
xmlns:h="http://xmlns.jcp.org/jsf/html"
xmlns:ui="http://xmlns.jcp.org/jsf/facelets">
If you can't upgrade to JSF 2.2 or higher, then you need to use the old java.sun.com XML namespaces instead:
<html lang="en"
xmlns="http://www.w3.org/1999/xhtml"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:ui="http://java.sun.com/jsf/facelets">
But ideally you should always use the latest version where available.
See also:
Which XML namespace to use with JSF 2.2 and up
JSF tags not executed
Warning: This page calls for XML namespace http://xmlns.jcp.org/jsf/XXX declared with prefix XXX but no taglibrary exists for that namespace
3. Multiple JSF implementations have been loaded
One more probable cause is that multiple JSF implementations have been loaded by your webapp, conflicting and corrupting each other. For example, when your webapp's runtime classpath is polluted with multiple different versioned JSF libraries, or in the specific Mojarra 2.x + Tomcat 8.x combination, when there's an unnecessary ConfigureListener entry in webapp's web.xml causing it to be loaded twice.
<!-- You MUST remove this one from web.xml! -->
<!-- This is actually a workaround for buggy GlassFish3 and Jetty servers. -->
<!-- When leaving this in and you're targeting Tomcat, you'll run into trouble. -->
<listener>
<listener-class>com.sun.faces.config.ConfigureListener</listener-class>
</listener>
When using Maven, make absolutely sure that you declare the dependencies the right way and that you understand dependency scopes. Importantingly, do not bundle dependencies in webapp when those are already provided by the target server.
See also:
Configuration of com.sun.faces.config.ConfigureListener
How to properly install and configure JSF libraries via Maven?
Make sure that you learn JSF the right way
JSF has a very steep learning curve for those unfamiliar with basic HTTP, HTML and Servlets. There are a lot of low quality resources on the Internet. Please ignore code snippet scraping sites maintained by amateurs with primary focus on advertisement income instead of on teaching, such as roseindia, tutorialspoint, javabeat, baeldung, etc. They are easily recognizable by disturbing advertising links/banners. Also please ignore resources dealing with jurassic JSF 1.x. They are easily recognizable by using JSP files instead of XHTML files. JSP as view technology was deprecated since JSF 2.0 at 2009 already.
To get started the right way, start at our JSF wiki page and order an authoritative book.
See also:
Java / Jakarta EE web development, where do I start and what skills do I need?
What is the need of JSF, when UI can be achieved with JavaScript libraries such as jQuery and AngularJS
This is what I have in the output HTML document (produced by JSF 2.0/Mojarra 2.0.3):
<input type="hidden" name="javax.faces.ViewState"
id="javax.faces.ViewState" value="4267906931114993858:-6309146738430577631"
autocomplete="off" />
My document should be XHTML 1.1 compliant, where attribute autocomplete is not valid and id attribute is duplicated over all forms. How to instruct JSF to produce everything strictly compliant to XHTML?
See.
<context-param>
<param-name>com.sun.faces.autoCompleteOffOnViewState</param-name>
<param-value>false</param-value>
</context-param>
<context-param>
<param-name>com.sun.faces.enableViewStateIdRendering</param-name>
<param-value>false</param-value>
</context-param>
The non unique use if the ID javax.faces.ViewState is a bug that appears Oracle will not fix. They have closed these tickets. No workaround.
How to instruct JSF to produce
everything strictly compliant to
XHTML?
That's not a matter of "instructing" the JSF implementation with a simple flag. It's something that has to be continuously checked and thus only possible when it's considered important by the project. XHTML strict imposes a lot of restrictions and is probably therefore generally not considered worth supporting - see this bug. Note also that any component library you use also has to support it.
You'll have a lot more luck with XHTML 1.0 Transitional - I can confirm that MyFaces does produce valid XHTML 1.0 Transitional (once you set the context param org.apache.myfaces.RENDER_VIEWSTATE_ID to false).
There is a solution to this problem, it was created in version 1.2_14 of JSF. I think the problem is related to the way that Firefox operates during the reset event (input type=reset) on hidden fields. There is a problem where the client viewState that is on a hidden field gets an inconsistent state. The solution for this problem was disabled the auto-complete in a strict way (and this is not XHTML compliant). The most interesting thing is that until 1.2_14 almost everybody lived with this potential error. So the JSF-RI implementation (Mojarra project) allowed a developer to disable this option using a parameter that you can edit in your web.xml, and this auto complete won't print anymore.
<context-param>
<description>Put your description here :)</description>
<param-name>com.sun.faces.autoCompleteOffOnViewState</param-name>
<param-value>false</param-value>
</context-param>
It is really difficult to produce valid XHTML pages with component based frameworks like JSF, but at least a solution exists for this problem.
It's not a good idea to disable autocomplete="off" for ViewState hidden input fields, because then Firefox doesn't refresh the ViewState-Id on page refresh. This causes unusable JSF forms and functionalities.
See this post for details.