struts-sandbox/tiles-original/core-library/src/java/org/apache/taglib/tiles/InsertTag.java

/*
 * Copyright 2004-2005 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.taglib.tiles;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Map;
import java.util.StringTokenizer;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.PageContext;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.tiles.Globals;
import org.apache.taglib.tiles.util.TagUtils;
import org.apache.tiles.AttributeDefinition;
import org.apache.tiles.ComponentContext;
import org.apache.tiles.ComponentDefinition;
import org.apache.tiles.Controller;
import org.apache.tiles.DefinitionAttribute;
import org.apache.tiles.DefinitionNameAttribute;
import org.apache.tiles.DefinitionsFactoryException;
import org.apache.tiles.DirectStringAttribute;
import org.apache.tiles.FactoryNotFoundException;
import org.apache.tiles.NoSuchDefinitionException;
import org.apache.tiles.TilesUtil;

/**
 * This is the tag handler for <tiles:insert>, which includes
 * a template. The tag's body content consists of <tiles:put>
 * tags, which are accessed by <tiles:get> in the template.
 *
 * @author David Geary
 * @author Cedric Dumoulin
 * @version $Revision: 1.20 $ $Date: 2003/07/07 23:40:12 $
 */
public class InsertTag
    extends DefinitionTagSupport
    implements PutTagParent, ComponentConstants, PutListTagParent {

    /** 
     * The role delimiter. 
     * @deprecated This will be removed in a release after Struts 1.2.
     */
    public static final String ROLE_DELIMITER = ",";

    /** 
     * Commons Logging instance. 
     */
    protected static Log log = LogFactory.getLog(InsertTag.class);

    /* JSP Tag attributes */

    /** 
     * Flush attribute value. 
     */
    protected boolean flush = true;

    /** 
     * Name to insert. 
     */
    protected String name = null;

    /**
     * Name of attribute from which to read page name to include. 
     */
    protected String attribute = null;

    /** 
     * Name of bean used as entity to include. 
     */
    protected String beanName = null;

    /** 
     * Name of bean property, if any. 
     */
    protected String beanProperty = null;

    /** 
     * Scope of bean, if any. 
     */
    protected String beanScope = null;

    /**
     * Are errors ignored. This is the property for attribute 'ignore'.
     * Default value is false, which throw an exception.
     * Only 'attribute not found' errors are ignored.
     */
    protected boolean isErrorIgnored = false;

    /**
     * Name of component instance to include.
     */
    protected String definitionName = null;

    /* Internal properties */
    /**
     * Does the end tag need to be processed.
     * Default value is true. Boolean set in case of ignored errors.
     */
    protected boolean processEndTag = true;

    /** 
     * Current component context. 
     */
    protected ComponentContext cachedCurrentContext;

    /** 
     * Final handler of tag methods. 
     */
    protected TagHandler tagHandler = null;

    /** 
     * Trick to allows inner classes to access pageContext. 
     */
    protected PageContext pageContext = null;

    /**
     * Reset member values for reuse. This method calls super.release(),
     * which invokes TagSupport.release(), which typically does nothing.
     */
    public void release() {

        super.release();
        attribute = null;
        beanName = null;
        beanProperty = null;
        beanScope = null;

        definitionName = null;
        flush = true;
        name = null;
        page = null;
        role = null;
        isErrorIgnored = false;

        releaseInternal();
    }

    /**
     * Reset internal member values for reuse.
     */
    protected void releaseInternal() {
        cachedCurrentContext = null;
        processEndTag = true;
        // pageContext = null;  // orion doesn't set it between two tags
        tagHandler = null;
    }

    /**
     * Set the current page context.
     * Called by the page implementation prior to doStartTag().
     * <p>
     * Needed to allow inner classes to access pageContext.
     */
    public void setPageContext(PageContext pc) {
        this.pageContext = pc;
        super.setPageContext(pc);
    }

    /**
     * Get the pageContext property.
     */
    public PageContext getPageContext() {
        return pageContext;
    }

    /**
     * Set name.
     */
    public void setName(String value) {
        this.name = value;
    }

    /**
     * Get name.
     */
    public String getName() {
        return name;
    }

    /**
     * Set component.
     */
    public void setComponent(String name) {
        this.page = name;
    }

    /**
     * Set definition.
     */
    public void setDefinition(String name) {
        this.definitionName = name;
    }

    /**
     * Get definition name.
     */
    public String getDefinitionName() {
        return definitionName;
    }

    /**
     * Set attribute.
     */
    public void setAttribute(String value) {
        this.attribute = value;
    }

    /**
     * Set bean name.
     */
    public void setBeanName(String value) {
        this.beanName = value;
    }

    /**
     * Get bean name.
     */
    public String getBeanName() {
        return beanName;
    }

    /**
     * Set bean property.
     */
    public void setBeanProperty(String value) {
        this.beanProperty = value;
    }

    /**
     * Get bean property.
     */
    public String getBeanProperty() {
        return beanProperty;
    }

    /**
     * Set bean scope.
     */
    public void setBeanScope(String value) {
        this.beanScope = value;
    }

    /**
     * Get bean scope.
     */
    public String getBeanScope() {
        return beanScope;
    }

    /**
     * Set flush.
     */
    public void setFlush(boolean flush) {
        this.flush = flush;
    }

    /**
     * Get flush.
     */
    public boolean getFlush() {
        return flush;
    }

    /**
     * Set flush.
     * Method added for compatibility with JSP1.1
     */
    public void setFlush(String flush) {
        this.flush = (Boolean.valueOf(flush).booleanValue());
    }

    /**
     * Set ignore.
     */
    public void setIgnore(boolean ignore) {
        this.isErrorIgnored = ignore;
    }

    /**
     * Get ignore.
     */
    public boolean getIgnore() {
        return isErrorIgnored;
    }

    /////////////////////////////////////////////////////////////////////////

    /**
     * Add a body attribute.
     * Erase any attribute with same name previously set.
     */
    public void putAttribute(String name, Object value) {
        tagHandler.putAttribute(name, value);
    }

    /**
     * Process nested &lg;put&gt; tag.
     * Method calls by nested &lg;put&gt; tags.
     * Nested list is added to current list.
     * If role is defined, it is checked immediately.
     */
    public void processNestedTag(PutTag nestedTag) throws JspException {
        // Check role
        HttpServletRequest request = (HttpServletRequest) pageContext.getRequest();
        String role = nestedTag.getRole();
        if (role != null && !request.isUserInRole(role)) {
            // not allowed : skip attribute
            return;
        }

        putAttribute(nestedTag.getName(), nestedTag.getRealValue());
    }

    /**
     * Process nested &lg;putList&gt; tag.
     * Method calls by nested &lg;putList&gt; tags.
     * Nested list is added to sub-component attributes
     * If role is defined, it is checked immediately.
     */
    public void processNestedTag(PutListTag nestedTag) throws JspException {
        // Check role
        HttpServletRequest request = (HttpServletRequest) pageContext.getRequest();
        String role = nestedTag.getRole();
        if (role != null && !request.isUserInRole(role)) {
            // not allowed : skip attribute
            return;
        }

        // Check if a name is defined
        if (nestedTag.getName() == null) {
            throw new JspException("Error - PutList : attribute name is not defined. It is mandatory as the list is added as attribute of 'insert'.");
        }

        // now add attribute to enclosing parent (i.e. : this object).
        putAttribute(nestedTag.getName(), nestedTag.getList());
    }

    /**
     * Method calls by nested &lg;putList&gt; tags.
     * A new list is added to current insert object.
     */
    public void putAttribute(PutListTag nestedTag) throws JspException {
        // Check role
        HttpServletRequest request = (HttpServletRequest) pageContext.getRequest();
        String role = nestedTag.getRole();
        if (role != null && !request.isUserInRole(role)) {
            // not allowed : skip attribute
            return;
        }

        putAttribute(nestedTag.getName(), nestedTag.getList());
    }

    /**
     * Get current component context.
     */
    private ComponentContext getCurrentContext() {
        if (cachedCurrentContext == null) {
            cachedCurrentContext =
                (ComponentContext) pageContext.getAttribute(
                    ComponentConstants.COMPONENT_CONTEXT,
                    PageContext.REQUEST_SCOPE);
        }

        return cachedCurrentContext;
    }

    /**
     * Get instantiated Controller.
     * Return controller denoted by controllerType, or <code>null</code> if controllerType
     * is null.
     * @throws JspException If controller can't be created.
     */
    private Controller getController() throws JspException {
        if (controllerType == null) {
            return null;
        }

        try {
            return ComponentDefinition.createController(
                controllerName,
                controllerType);

        } catch (InstantiationException ex) {
            throw new JspException(ex.getMessage());
        }
    }

    /**
     * Process the start tag by checking tag's attributes and creating appropriate handler.
     * Possible handlers :
     * <ul>
     * <li> URL
     * <li> definition
     * <li> direct String
     * </ul>
     * Handlers also contain sub-component context.
     */
    public int doStartTag() throws JspException {
        // Check role immediatly to avoid useless stuff.
        // In case of insertion of a "definition", definition's role still checked later.
        // This lead to a double check of "role" ;-(
        HttpServletRequest request = (HttpServletRequest) pageContext.getRequest();
        if (role != null && !request.isUserInRole(role)) {
            processEndTag = false;
            return SKIP_BODY;
        }

        try {
            tagHandler = createTagHandler();

        } catch (JspException e) {
            if (isErrorIgnored) {
                processEndTag = false;
                return SKIP_BODY;
            } else {
                throw e;
            }
        }

        return tagHandler.doStartTag();
    }

    /**
     * Process the end tag by including the template.
     * Simply call the handler doEndTag
     */
    public int doEndTag() throws JspException {
        if (!processEndTag) {
            releaseInternal();
            return EVAL_PAGE;
        }

        int res = tagHandler.doEndTag();
        // Reset properties used by object, in order to be able to reuse object.
        releaseInternal();
        return res;
    }

    /**
     * Process tag attribute and create corresponding tag handler.
     */
    public TagHandler createTagHandler() throws JspException {
        // Check each tag attribute.
        // page Url attribute must be the last checked  because it can appears concurrently
        // with others attributes.
        if (definitionName != null) {
            return processDefinitionName(definitionName);
        } else if (attribute != null) {
            return processAttribute(attribute);
        } else if (beanName != null) {
            return processBean(beanName, beanProperty, beanScope);
        } else if (name != null) {
            return processName(name);
        } else if (page != null) {
            return processUrl(page);
        } else {
            throw new JspException("Error - Tag Insert : At least one of the following attribute must be defined : template|page|attribute|definition|name|beanName. Check tag syntax");
        }
    }

    /**
     * Process an object retrieved as a bean or attribute.
     * Object can be a typed attribute, a String, or anything else.
     * If typed attribute, use associated type.
     * Otherwise, apply toString() on object, and use returned string as a name.
     * @throws JspException - Throws by underlying nested call to 
     * processDefinitionName()
     */
    public TagHandler processObjectValue(Object value) throws JspException {
        // First, check if value is one of the Typed Attribute
        if (value instanceof AttributeDefinition) {
            // We have a type => return appropriate IncludeType
            return processTypedAttribute((AttributeDefinition) value);

        } else if (value instanceof ComponentDefinition) {
            return processDefinition((ComponentDefinition) value);
        }

        // Value must denote a valid String
        return processAsDefinitionOrURL(value.toString());
    }

    /**
     * Process name.
     * Search in following order :
     * <ul>
     * <li>Component context -  if found, process it as value.</li>
     * <li>definitions factory</li>
     * <li>URL</li>
     * <li></li>
     * </ul>
     *
     * @return appropriate tag handler.
     * @throws JspException - Throws by underlying nested call to 
     * processDefinitionName()
     */
    public TagHandler processName(String name) throws JspException {
        Object attrValue = getCurrentContext().getAttribute(name);

        if (attrValue != null) {
            return processObjectValue(attrValue);
        }

        return processAsDefinitionOrURL(name);
    }

    /**
     * Process the url.
     * @throws JspException If failed to create controller
     */
    public TagHandler processUrl(String url) throws JspException {
        return new InsertHandler(url, role, getController());
    }

    /**
     * Process tag attribute "definition".
     * First, search definition in the factory, then create handler from this definition.
     * @param name Name of the definition.
     * @return Appropriate TagHandler.
     * @throws JspException- NoSuchDefinitionException No Definition  found for name.
     * @throws JspException- FactoryNotFoundException Can't find Definitions factory.
     * @throws JspException- DefinedComponentFactoryException General error in factory.
     * @throws JspException InstantiationException Can't create requested controller
     */
    protected TagHandler processDefinitionName(String name) throws JspException {

        try {
            ComponentDefinition definition =
                TilesUtil.getDefinition(
                    name,
                    (HttpServletRequest) pageContext.getRequest(),
                    pageContext.getServletContext());

            if (definition == null) { // is it possible ?
                throw new NoSuchDefinitionException();
            }

            return processDefinition(definition);

        } catch (NoSuchDefinitionException ex) {
            throw new JspException(
                "Error -  Tag Insert : Can't get definition '"
                    + definitionName
                    + "'. Check if this name exist in definitions factory.");

        } catch (FactoryNotFoundException ex) {
				log.info("FACTORY NOT FOUND");
				String msg = (String)pageContext.getServletContext()
					                             .getAttribute(Globals.TILES_INIT_EXCEPTION);
            throw new JspException(msg);

        } catch (DefinitionsFactoryException ex) {
				log.info("DEFINITIONS FACTORY EXCEPTION");
            if (log.isDebugEnabled()) {
                ex.printStackTrace();
            }

            // Save exception to be able to show it later
            pageContext.setAttribute(
                Globals.EXCEPTION_KEY,
                ex,
                PageContext.REQUEST_SCOPE);
            throw new JspException(ex.getMessage());
        }
    }

    /**
     * End of Process tag attribute "definition".
     * Overload definition with tag attributes "template" and "role".
     * Then, create appropriate tag handler.
     * @param definition Definition to process.
     * @return Appropriate TagHandler.
     * @throws JspException InstantiationException Can't create requested controller
     */
    protected TagHandler processDefinition(ComponentDefinition definition)
        throws JspException {
        // Declare local variable in order to not change Tag attribute values.
        String role = this.role;
        String page = this.page;
        Controller controller = null;

        try {
            controller = definition.getOrCreateController();

            // Overload definition with tag's template and role.
            if (role == null) {
                role = definition.getRole();
            }

            if (page == null) {
                page = definition.getTemplate();
            }

            if (controllerName != null) {
                controller =
                    ComponentDefinition.createController(
                        controllerName,
                        controllerType);
            }

            // Can check if page is set
            return new InsertHandler(
                definition.getAttributes(),
                page,
                role,
                controller);

        } catch (InstantiationException ex) {
            throw new JspException(ex.getMessage());
        }
    }

    /**
     * Process a bean.
     * Get bean value, eventually using property and scope. Found value is process by processObjectValue().
     * @param beanName Name of the bean
     * @param beanProperty Property in the bean, or null.
     * @param beanScope bean scope, or null.
     * @return Appropriate TagHandler.
     * @throws JspException - NoSuchDefinitionException No value associated to bean.
     * @throws JspException an error occur while reading bean, or no definition found.
     * @throws JspException - Throws by underlying nested call to processDefinitionName()
     */
    protected TagHandler processBean(
        String beanName,
        String beanProperty,
        String beanScope)
        throws JspException {

        Object beanValue =
            TagUtils.getRealValueFromBean(
                beanName,
                beanProperty,
                beanScope,
                pageContext);

        if (beanValue == null) {
            throw new JspException(
                "Error - Tag Insert : No value defined for bean '"
                    + beanName
                    + "' with property '"
                    + beanProperty
                    + "' in scope '"
                    + beanScope
                    + "'.");
        }

        return processObjectValue(beanValue);
    }

    /**
     * Process tag attribute "attribute".
     * Get value from component attribute.
     * Found value is process by processObjectValue().
     * @param name Name of the attribute.
     * @return Appropriate TagHandler.
     * @throws JspException - NoSuchDefinitionException No Definition  found for name.
     * @throws JspException - Throws by underlying nested call to processDefinitionName()
     */
    public TagHandler processAttribute(String name) throws JspException {
        Object attrValue = getCurrentContext().getAttribute(name);

        if (attrValue == null) {
            throw new JspException(
                "Error - Tag Insert : No value found for attribute '" + name + "'.");
        }

        return processObjectValue(attrValue);
    }

    /**
     * Try to process name as a definition, or as an URL if not found.
     * @param name Name to process.
     * @return appropriate TagHandler
     * @throws JspException InstantiationException Can't create requested controller
     */
    public TagHandler processAsDefinitionOrURL(String name) throws JspException {
        try {
            ComponentDefinition definition =
                TilesUtil.getDefinition(
                    name,
                    pageContext.getRequest(),
                    pageContext.getServletContext());

            if (definition != null) {
                return processDefinition(definition);
            }

        } catch (DefinitionsFactoryException ex) {
            // silently failed, because we can choose to not define a factory.
        }

        // no definition found, try as url
        return processUrl(name);
    }

    /**
     * Process typed attribute according to its type.
     * @param value Typed attribute to process.
     * @return appropriate TagHandler.
     * @throws JspException - Throws by underlying nested call to processDefinitionName()
     */
    public TagHandler processTypedAttribute(AttributeDefinition value)
        throws JspException {
        if (value instanceof DirectStringAttribute) {
            return new DirectStringHandler((String) value.getValue());

        } else if (value instanceof DefinitionAttribute) {
            return processDefinition((ComponentDefinition) value.getValue());

        } else if (value instanceof DefinitionNameAttribute) {
            return processDefinitionName((String) value.getValue());
        }

        return new InsertHandler((String) value.getValue(), role, getController());
    }

    /**
     * Do an include of specified page.
     * This method is used internally to do all includes from this class. It delegates
     * the include call to the TilesUtil.doInclude().
     * @param page The page that will be included
     * @throws ServletException - Thrown by call to pageContext.include()
     * @throws IOException - Thrown by call to pageContext.include()
     */
    protected void doInclude(String page) throws ServletException, IOException {
        TilesUtil.doInclude(page, pageContext);
    }

    /////////////////////////////////////////////////////////////////////////////

    /**
     * Inner Interface.
     * Sub handler for tag.
     */
    protected interface TagHandler {
        /**
         * Create ComponentContext for type depicted by implementation class.
         */
        public int doStartTag() throws JspException;
        /**
         * Do include for type depicted by implementation class.
         */
        public int doEndTag() throws JspException;
        /**
         * Add a component parameter (attribute) to subContext.
         */
        public void putAttribute(String name, Object value);
    } // end inner interface

    /////////////////////////////////////////////////////////////////////////////

    /**
     * Real handler, after attribute resolution.
     * Handle include sub-component.
     */
    protected class InsertHandler implements TagHandler {
        protected String page;
        protected ComponentContext currentContext;
        protected ComponentContext subCompContext;
        protected String role;
        protected Controller controller;

        /**
         * Constructor.
         * Create insert handler using Component definition.
         */
        public InsertHandler(
            Map attributes,
            String page,
            String role,
            Controller controller) {

            this.page = page;
            this.role = role;
            this.controller = controller;
            subCompContext = new ComponentContext(attributes);
        }

        /**
         * Constructor.
         * Create insert handler to insert page at specified location.
         */
        public InsertHandler(String page, String role, Controller controller) {
            this.page = page;
            this.role = role;
            this.controller = controller;
            subCompContext = new ComponentContext();
        }

        /**
         * Create a new empty context.
         */
        public int doStartTag() throws JspException {
            // Check role
            HttpServletRequest request =
                (HttpServletRequest) pageContext.getRequest();

            if (role != null && !request.isUserInRole(role)) {
                return SKIP_BODY;
            }

            // save current context
            this.currentContext = getCurrentContext();
            return EVAL_BODY_INCLUDE;
        }

        /**
         * Add attribute to sub context.
         * Do nothing.
         */
        public void putAttribute(String name, Object value) {
            subCompContext.putAttribute(name, value);
        }

        /**
         * Include requested page.
         */
        public int doEndTag() throws JspException {
            // Check role
            HttpServletRequest request =
                (HttpServletRequest) pageContext.getRequest();

            if (role != null && !request.isUserInRole(role)) {
                return EVAL_PAGE;
            }

            try {
                if (log.isDebugEnabled()) {
                    log.debug("insert page='" + page + "'.");
                }

                // set new context for included component.
                pageContext.setAttribute(
                    ComponentConstants.COMPONENT_CONTEXT,
                    subCompContext,
                    PageContext.REQUEST_SCOPE);

                // Call controller if any
                if (controller != null) {
                    controller.perform(
                        subCompContext,
                        (HttpServletRequest) pageContext.getRequest(),
                        (HttpServletResponse) pageContext.getResponse(),
                        pageContext.getServletContext());
                }

                // include requested component.
                //if (flush) {
                 //   pageContext.getOut().flush();
                //}

					 System.out.println("INCLUDING " + page);
                doInclude(page);

            } catch (IOException e) {
                String msg = "Can't insert page '" + page + "' : " + e.getMessage();
                log.error(msg, e);
                throw new JspException(msg);

            } catch (IllegalArgumentException e) {
                // Can't resolve page uri, should we ignore it?
                if (!(page == null && isErrorIgnored)) {
                    String msg =
                        "Can't insert page '"
                            + page
                            + "'. Check if it exists.\n"
                            + e.getMessage();

                    log.error(msg, e);
                    throw new JspException(msg);
                }

            } catch (ServletException e) {
                Throwable cause = e;
                if (e.getRootCause() != null) {
                    cause = e.getRootCause();
                }

                String msg =
                    "ServletException in '" + page + "': " + cause.getMessage();

                log.error(msg, e);
                throw new JspException(msg);


            } finally {
                // restore old context only if currentContext not null 
                // (bug with Silverstream ?; related by Arvindra Sehmi 20010712)
                if (currentContext != null) {
                    pageContext.setAttribute(
                        ComponentConstants.COMPONENT_CONTEXT,
                        currentContext,
                        PageContext.REQUEST_SCOPE);
                }
            }
            
            return EVAL_PAGE;
        }

        /**
         * Process an exception.
         * Depending of debug attribute, print full exception trace or only
         * its message in output page.
         * @param ex Exception
         * @param msg An additional message to show in console and to propagate if we can't output exception.
         * @deprecated This method will be removed in a release after Struts 1.2.
         */
        protected void processException(Throwable ex, String msg)
            throws JspException {

            try {
                if (msg == null) {
                    msg = ex.getMessage();
                }

                if (log.isDebugEnabled()) { // show full trace
                    log.debug(msg, ex);
                    pageContext.getOut().println(msg);
                    ex.printStackTrace(new PrintWriter(pageContext.getOut(), true));
                } else { // show only message
                    pageContext.getOut().println(msg);
                }

            } catch (IOException ioex) { // problems. Propagate original exception
                pageContext.setAttribute(
                    ComponentConstants.EXCEPTION_KEY,
                    ex,
                    PageContext.REQUEST_SCOPE);
                throw new JspException(msg);
            }
        }
    }

    /**
     * Parse the list of roles and return <code>true</code> or <code>false</code> based on whether
     * the user has that role or not.
     * @param role Comma-delimited list of roles.
     * @param request The request.
     */
    static public boolean userHasRole(HttpServletRequest request, String role) {
        StringTokenizer st = new StringTokenizer(role, ",");
        while (st.hasMoreTokens()) {
            if (request.isUserInRole(st.nextToken())) {
                return true;
            }
        }

        return false;
    }

    /////////////////////////////////////////////////////////////////////////////

    /**
     * Handle insert direct string.
     */
    protected class DirectStringHandler implements TagHandler {
        /** Object to print as a direct string */
        private Object value;

        /**
         * Constructor.
         */
        public DirectStringHandler(Object value) {
            this.value = value;
        }

        /**
         * Do nothing, there is no context for a direct string.
         */
        public int doStartTag() throws JspException {
            return SKIP_BODY;
        }

        /**
         * Add attribute to sub context.
         * Do nothing.
         */
        public void putAttribute(String name, Object value) {
        }

        /**
         * Print String in page output stream.
         */
        public int doEndTag() throws JspException {
            try {
                if (flush) {
                    pageContext.getOut().flush();
                }

                pageContext.getOut().print(value);

            } catch (IOException ex) {
                if (log.isDebugEnabled()) {
                    log.debug("Can't write string '" + value + "' : ", ex);
                }

                pageContext.setAttribute(
                    ComponentConstants.EXCEPTION_KEY,
                    ex,
                    PageContext.REQUEST_SCOPE);

                throw new JspException(
                    "Can't write string '" + value + "' : " + ex.getMessage());
            }

            return EVAL_PAGE;
        }
    }
}