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Commons Digester example source code file (VariableAttributes.java)

This example Commons Digester source code file (VariableAttributes.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 - Commons Digester tags/keywords

arraylist, arraylist, attributes, attributes, sax, string, string, util, variableattributes, variableexpander, variableexpander

The Commons Digester VariableAttributes.java source code

/* $Id: VariableAttributes.java 992060 2010-09-02 19:09:47Z simonetripodi $
 * 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,
 * See the License for the specific language governing permissions and
 * limitations under the License.

package org.apache.commons.digester.substitution;

import org.xml.sax.Attributes;

import java.util.ArrayList;

 * <p>Wrapper for an org.xml.sax.Attributes object which expands any 
 * "variables" referenced in the attribute value via ${foo} or similar. 
 * This is only done when something actually asks for the attribute value, 
 * thereby imposing no performance penalty if the attribute is not used.</p>
 * @since 1.6

public class VariableAttributes implements Attributes {

    // list of mapped attributes.
    private ArrayList<String> values = new ArrayList(10);

    private Attributes attrs;
    private VariableExpander expander;
    // ------------------- Public Methods
     * Specify which attributes class this object is a proxy for.
    public void init(Attributes attrs, VariableExpander expander) {
        this.attrs = attrs;
        this.expander = expander;

        // I hope this doesn't release the memory for this array; for 
        // efficiency, this should just mark the array as being size 0.

    public String getValue(int index) {
        if (index >= values.size()) {
            // Expand the values array with null elements, so the later
            // call to set(index, s) works ok.
            // Unfortunately, there is no easy way to set the size of
            // an arraylist; we must repeatedly add null elements to it..
            for(int i = values.size(); i<= index; ++i) {
        String s = values.get(index);
        if (s == null) {
            // we have never been asked for this value before.
            // get the real attribute value and perform substitution
            // on it.
            s = attrs.getValue(index);
            if (s != null) {
                s = expander.expand(s);
                values.set(index, s);
        return s;
    public String getValue(String qname) {
        int index = attrs.getIndex(qname);
        if (index == -1) {
            return null;
        return getValue(index);
    public String getValue(String uri, String localname) {
        int index = attrs.getIndex(uri, localname);
        if (index == -1) {
            return null;
        return getValue(index);
    // plain proxy methods follow : nothing interesting :-)
    public int getIndex(String qname) {
        return attrs.getIndex(qname); 
    public int getIndex(String uri, String localpart) {
        return attrs.getIndex(uri, localpart); 
    public int getLength() {
        return attrs.getLength();
    public String getLocalName(int index) {
        return attrs.getLocalName(index);
    public String getQName(int index) {
        return attrs.getQName(index);
    public String getType(int index) {
        return attrs.getType(index);

    public String getType(String qname) {
        return attrs.getType(qname);
    public String getType(String uri, String localname) {
        return attrs.getType(uri, localname);
    public String getURI(int index) {
        return attrs.getURI(index);

Other Commons Digester examples (source code examples)

Here is a short list of links related to this Commons Digester VariableAttributes.java source code file:

my book on functional programming


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