Struts example source code file (AppendIterator.java)

This example Struts source code file (AppendIterator.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

appenditerator, appenditerator, appenditeratorfilter, appenditeratorfilter, arraylist, contextbean, io, iterator, list, logger, object, object, string, strutstag, the, util

The Struts AppendIterator.java source code

/*
 * $Id: AppendIterator.java 651946 2008-04-27 13:41:38Z apetrelli $
 *
 * 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.components;

import java.io.Writer;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.apache.struts2.components.Param.UnnamedParametric;
import org.apache.struts2.util.AppendIteratorFilter;
import org.apache.struts2.util.MakeIterator;
import org.apache.struts2.views.annotations.StrutsTag;
import org.apache.struts2.views.annotations.StrutsTagAttribute;

import com.opensymphony.xwork2.util.ValueStack;
import com.opensymphony.xwork2.util.logging.Logger;
import com.opensymphony.xwork2.util.logging.LoggerFactory;

/**
 * <!-- START SNIPPET: javadoc -->
 * <p>Component for AppendIteratorTag, which jobs is to append iterators to form an
 * appended iterator whereby entries goes from one iterator to another after each
 * respective iterator is exhausted of entries.</p>
 *
 * <p>For example, if there are 3 iterator appended (each iterator has 3 entries),
 * the following will be how the appended iterator entries will be arranged:</p>
 *
 * <ol>
 *      <li>First Entry of the First Iterator
 *      <li>Second Entry of the First Iterator
 *      <li>Third Entry of the First Iterator
 *      <li>First Entry of the Second Iterator
 *      <li>Second Entry of the Second Iterator
 *      <li>Third Entry of the Second Iterator
 *      <li>First Entry of the Third Iterator
 *      <li>Second Entry of the Third Iterator
 *      <li>Third Entry of the Third ITerator
 * </ol>
 * <!-- END SNIPPET: javadoc -->
 *
 * <!-- START SNIPPET: params -->
 * <ul>
 *      <li>id (String) - the id of which if supplied will have the resultant
 *                        appended iterator stored under in the stack's context</li>
 * </ul>
 * <!-- END SNIPPET: params -->
 *
 *
 * <!-- START SNIPPET: code -->
 * public class AppendIteratorTagAction extends ActionSupport {
 *
 *  private List myList1;
 *  private List myList2;
 *  private List myList3;
 *
 *
 *  public String execute() throws Exception {
 *
 *      myList1 = new ArrayList();
 *      myList1.add("1");
 *      myList1.add("2");
 *      myList1.add("3");
 *
 *      myList2 = new ArrayList();
 *      myList2.add("a");
 *      myList2.add("b");
 *      myList2.add("c");
 *
 *      myList3 = new ArrayList();
 *      myList3.add("A");
 *      myList3.add("B");
 *      myList3.add("C");
 *
 *      return "done";
 *  }
 *
 *  public List getMyList1() { return myList1; }
 *  public List getMyList2() { return myList2; }
 *  public List getMyList3() { return myList3; }
 *}
 * <!-- END SNIPPET: code -->
 *
 * <!-- START SNIPPET: example -->
 * <s:append var="myAppendIterator">
 *      <s:param value="%{myList1}" />
 *      <s:param value="%{myList2}" />
 *      <s:param value="%{myList3}" />
 * </s:append>
 * <s:iterator value="%{#myAppendIterator}">
 *      <s:property />
 * </s:iterator>
 * <!-- END SNIPPET: example -->
 *
 *
 * @see org.apache.struts2.util.AppendIteratorFilter
 * @see org.apache.struts2.views.jsp.iterator.AppendIteratorTag
 *
 */
@StrutsTag(name="append", tldTagClass="org.apache.struts2.views.jsp.iterator.AppendIteratorTag", description="Append the values of a list of iterators to one iterator")
public class AppendIterator extends ContextBean implements UnnamedParametric {

    private static final Logger LOG = LoggerFactory.getLogger(AppendIterator.class);

    private AppendIteratorFilter appendIteratorFilter= null;
    private List _parameters;

    public AppendIterator(ValueStack stack) {
        super(stack);
    }

    public boolean start(Writer writer) {
        _parameters = new ArrayList();
        appendIteratorFilter = new AppendIteratorFilter();

        return super.start(writer);
    }

    public boolean end(Writer writer, String body) {

        for (Iterator paramEntries = _parameters.iterator(); paramEntries.hasNext(); ) {

            Object iteratorEntryObj = paramEntries.next();
            if (! MakeIterator.isIterable(iteratorEntryObj)) {
                LOG.warn("param with value resolved as "+iteratorEntryObj+" cannot be make as iterator, it will be ignored and hence will not appear in the merged iterator");
                continue;
            }
            appendIteratorFilter.setSource(MakeIterator.convert(iteratorEntryObj));
        }

        appendIteratorFilter.execute();

        putInContext(appendIteratorFilter);

        appendIteratorFilter = null;

        return super.end(writer, body);
    }

    // UnnamedParametric implementation --------------------------------------
    public void addParameter(Object value) {
        _parameters.add(value);
    }

    @StrutsTagAttribute(description="The name of which if supplied will have the resultant appended iterator stored under in the stack's context")
    public void setVar(String var) {
        super.setVar(var);
    }
}