Struts example source code file (TagModel.java)

This example Struts source code file (TagModel.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Struts tags/keywords

component, hashmap, http, httpservletresponse, io, iterator, iterator, map, map, object, object, request, response, servlet, simplenumber, simplesequence, simplesequence, tagmodel, templatemodelexception, util

The Struts TagModel.java source code

/*
 * $Id: TagModel.java 953221 2010-06-10 05:45:49Z lukaszlenart $
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.struts2.views.freemarker.tags;

import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.inject.Container;
import com.opensymphony.xwork2.util.ValueStack;
import com.opensymphony.xwork2.util.logging.Logger;
import com.opensymphony.xwork2.util.logging.LoggerFactory;
import freemarker.ext.beans.BeansWrapper;
import freemarker.template.SimpleNumber;
import freemarker.template.SimpleSequence;
import freemarker.template.TemplateModel;
import freemarker.template.TemplateModelException;
import freemarker.template.TemplateTransformModel;
import org.apache.struts2.components.Component;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.Writer;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

public abstract class TagModel implements TemplateTransformModel {
    private static final Logger LOG = LoggerFactory.getLogger(TagModel.class);

    protected ValueStack stack;
    protected HttpServletRequest req;
    protected HttpServletResponse res;

    public TagModel(ValueStack stack, HttpServletRequest req, HttpServletResponse res) {
        this.stack = stack;
        this.req = req;
        this.res = res;
    }

    public Writer getWriter(Writer writer, Map params)
        throws TemplateModelException, IOException {
        Component bean = getBean();
        Container container = (Container) stack.getContext().get(ActionContext.CONTAINER);
        container.inject(bean);

        Map unwrappedParameters = unwrapParameters(params);
        bean.copyParams(unwrappedParameters);

        return new CallbackWriter(bean, writer);
    }

    protected abstract Component getBean();

    protected Map unwrapParameters(Map params) {
        Map map = new HashMap(params.size());
        BeansWrapper objectWrapper = BeansWrapper.getDefaultInstance();
        for (Iterator iterator = params.entrySet().iterator(); iterator.hasNext();) {
            Map.Entry entry = (Map.Entry) iterator.next();

            Object value = entry.getValue();

            if (value != null) {
                // the value should ALWAYS be a decendant of TemplateModel
                if (value instanceof TemplateModel) {
                    try {
                        map.put(entry.getKey(), objectWrapper
                            .unwrap((TemplateModel) value));
                    } catch (TemplateModelException e) {
                        LOG.error("failed to unwrap [" + value
                            + "] it will be ignored", e);
                    }
                }
                // if it doesn't, we'll do it the old way by just returning the toString() representation
                else {
                    map.put(entry.getKey(), value.toString());
                }
            }
        }
        return map;
    }

    protected Map convertParams(Map params) {
        HashMap map = new HashMap(params.size());
        for (Iterator iterator = params.entrySet().iterator(); iterator.hasNext();) {
            Map.Entry entry = (Map.Entry) iterator.next();
            Object value = entry.getValue();
            if (value != null && !complexType(value)) {
                map.put(entry.getKey(), value.toString());
            }
        }
        return map;
    }

    protected Map getComplexParams(Map params) {
        HashMap map = new HashMap(params.size());
        for (Iterator iterator = params.entrySet().iterator(); iterator.hasNext();) {
            Map.Entry entry = (Map.Entry) iterator.next();
            Object value = entry.getValue();
            if (value != null && complexType(value)) {
                if (value instanceof freemarker.ext.beans.BeanModel) {
                    map.put(entry.getKey(), ((freemarker.ext.beans.BeanModel) value).getWrappedObject());
                } else if (value instanceof SimpleNumber) {
                    map.put(entry.getKey(), ((SimpleNumber) value).getAsNumber());
                } else if (value instanceof SimpleSequence) {
                    try {
                        map.put(entry.getKey(), ((SimpleSequence) value).toList());
                    } catch (TemplateModelException e) {
                        LOG.error("There was a problem converting a SimpleSequence to a list", e);
                    }
                }
            }
        }
        return map;
    }

    protected boolean complexType(Object value) {
        return value instanceof freemarker.ext.beans.BeanModel
                || value instanceof SimpleNumber
                || value instanceof SimpleSequence;
    }
}