Question

I want to create my own tag, but it doesn’t work

Component:

package com;

import javax.faces.component.UIOutput;
import javax.faces.context.FacesContext;
import javax.faces.context.ResponseWriter;
import java.io.IOException;

public class Printer extends UIOutput {
    private String label;

    public String getLabel() {
        return label;
    }

    public void setLabel(String label) {
        this.label = label;
    }

    @Override
    public Object saveState(FacesContext context) {
        Object values[] = new Object[2];
        values[0] = super.saveState(context);
        values[1] = label;
        return ((Object) (values));
    }

    @Override
    public void restoreState(FacesContext context, Object state) {
        Object values[] = (Object[]) state;
        super.restoreState(context, values[0]);
        label = (String) values[1];
    }

    public void encodeBegin(FacesContext context)
            throws IOException {

        ResponseWriter writer =
                context.getResponseWriter();

        writer.startElement("label", this);
        writer.write(label);
        writer.endElement("label");
        writer.flush();
    }

    public String getFamily() {
        return "printer";
    }

    public void encodeEnd(FacesContext context)
            throws IOException {
        return;
    }

    public void decode(FacesContext context) {
        return;
    }
}

Tag

package com;

import javax.faces.component.UIComponent;
import javax.faces.webapp.UIComponentELTag;

public class PrinterTag extends UIComponentELTag {
    private String label;

    public PrinterTag() {
        int i = 10;
    }

    public String getLabel() {
        return label;
    }

    public void setLabel(String label) {
        this.label = label;
    }

    @Override
    public String getComponentType() {
        return "printer";
    }

    @Override
    public String getRendererType() {
        return null;
    }

    protected void setProperties(UIComponent component) {
        super.setProperties(component);
        ((Printer) component).setLabel(label);
    }
}

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
          http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
         version="2.5">
    <context-param>
        <description>
        </description>
        <param-name>javax.faces.CONFIG_FILES</param-name>
        <param-value>
            /WEB-INF/faces-config.xml
        </param-value>
    </context-param>
    <servlet>
        <servlet-name>Faces Servlet</servlet-name>
        <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>/faces/*</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>*.faces</url-pattern>
    </servlet-mapping>
    <jsp-config>
        <taglib>
            <taglib-uri>http://ff.com</taglib-uri>
            <taglib-location>/WEB-INF/ff.tld</taglib-location>
        </taglib>
    </jsp-config>
    <listener>
        <listener-class>com.sun.faces.config.ConfigureListener</listener-class>
    </listener>
</web-app>

tld

<?xml version="1.0" encoding="ISO-8859-1"?>
<taglib xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd"
        xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.1">

    <display-name>RichFaces</display-name>
    <tlib-version>3.3.3</tlib-version>
    <short-name>ff</short-name>
    <uri>http://ff.com</uri>
    <tag>
        <name>mylabel</name>
        <tag-class>com.PrinterTag</tag-class>
        <body-content>tagdependent</body-content>
        <attribute>
            <description>The attribute takes a value-binding expression for a component property of
                a backing bean
            </description>
            <name>label</name>
            <rtexprvalue>false</rtexprvalue>
            <type>java.lang.String</type>
        </attribute>
    </tag>
</taglib>

faces-config

<?xml version='1.0' encoding='UTF-8'?>
<faces-config xmlns="http://java.sun.com/xml/ns/javaee"
              xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
              xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facesconfig_2_0.xsd"
              version="2.0">
    <component>
        <component-type>printer</component-type>
        <component-class>com.Printer</component-class>
    </component>
</faces-config>

test.xhtml

<!DOCTYPE html
        PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
        "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:h="http://java.sun.com/jsf/html"
      xmlns:ui="http://java.sun.com/jsf/facelets"
      xmlns:ff="http://ff.com">

<h:head>
    <title>Simple JSF Facelets page</title>
</h:head>
<h:body>
     before-<ff:mylabel label="This is my first tag"/>-after
</h:body>
</html>

(prints before–after)

I’m using
2.0.1-FCS jsf-api/jsf.impl/jstl-1.1.0
jsp-api/servlet-api/standart

Where I’m wrong?

Answer 1

You’ve definied the tag in a JSP TLD, while you’re using JSP’s successor Facelets. You need to define the tag in a Facelets TLD.

When reading tutorials/books about creating custom JSF components, ensure that you’re reading the JSF 2.0 targeted ones, not the JSF 1.2 targeted ones.

See also:

• Java EE 6 Tutorial – creating Custom UI Components
  • Steps for Creating a Custom Component
  • Creating Custom Component classes
  • Delegating Rendering to a Renderer
  • Defining the Custom Component Tag in a Tag Library Descriptor <– this one.