Spring Framework example source code file (HtmlCharacterEntityReferences.java)

This example Spring Framework source code file (HtmlCharacterEntityReferences.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 - Spring Framework tags/keywords

char_null, char_null, character, character, htmlcharacterentityreferences, illegalstateexception, invalid, io, ioexception, properties, reference_end, reference_end, reference_start, string, string, util

The Spring Framework HtmlCharacterEntityReferences.java source code

/*
 * Copyright 2002-2005 the original author or authors.
 *
 * 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.springframework.web.util;

import java.io.IOException;
import java.io.InputStream;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;

import org.springframework.util.Assert;

/**
 * Represents a set of character entity references defined by the
 * HTML 4.0 standard.
 *
 * <p>A complete description of the HTML 4.0 character set can be found
 * at http://www.w3.org/TR/html4/charset.html.
 *
 * @author Juergen Hoeller
 * @author Martin Kersten
 * @since 1.2.1
 */
class HtmlCharacterEntityReferences {

	static final char REFERENCE_START = '&';

	static final String DECIMAL_REFERENCE_START = "&#";

	static final String HEX_REFERENCE_START = "&#x";

	static final char REFERENCE_END = ';';

	static final char CHAR_NULL = (char) -1;


	private static final String PROPERTIES_FILE = "HtmlCharacterEntityReferences.properties";


	private final String[] characterToEntityReferenceMap = new String[3000];

	private final Map entityReferenceToCharacterMap = new HashMap(252);


	/**
	 * Returns a new set of character entity references reflecting the HTML 4.0 character set.
	 */
	public HtmlCharacterEntityReferences() {
		Properties entityReferences = new Properties();

		// Load refeence definition file.
		InputStream is = HtmlCharacterEntityReferences.class.getResourceAsStream(PROPERTIES_FILE);
		if (is == null) {
			throw new IllegalStateException(
					"Cannot find reference definition file [HtmlCharacterEntityReferences.properties] as class path resource");
		}
		try {
			try {
				entityReferences.load(is);
			}
			finally {
				is.close();
			}
		}
		catch (IOException ex) {
			throw new IllegalStateException(
					"Failed to parse reference definition file [HtmlCharacterEntityReferences.properties]: " +  ex.getMessage());
		}

		// Parse reference definition properites.
		Enumeration keys = entityReferences.propertyNames();
		while (keys.hasMoreElements()) {
			String key = (String) keys.nextElement();
			int referredChar = Integer.parseInt(key);
			Assert.isTrue((referredChar < 1000 || (referredChar >= 8000 && referredChar < 10000)),
					"Invalid reference to special HTML entity: " + referredChar);
			int index = (referredChar < 1000 ? referredChar : referredChar - 7000);
			String reference = entityReferences.getProperty(key);
			this.characterToEntityReferenceMap[index] = REFERENCE_START + reference + REFERENCE_END;
			this.entityReferenceToCharacterMap.put(reference, new Character((char) referredChar));
		}
	}

	/**
	 * Return the number of supported entity references.
	 */
	public int getSupportedReferenceCount() {
		return this.entityReferenceToCharacterMap.size();
	}

	/**
	 * Return true if the given character is mapped to a supported entity reference.
	 */
	public boolean isMappedToReference(char character) {
		return (convertToReference(character) != null);
	}

	/**
	 * Return the reference mapped to the given character or <code>null.
	 */
	public String convertToReference(char character) {
		if (character < 1000 || (character >= 8000 && character < 10000)) {
			int index = (character < 1000 ? character : character - 7000);
			String entityReference = this.characterToEntityReferenceMap[index];
			if (entityReference != null) {
				return entityReference;
			}
		}
		return null;
	}

	/**
	 * Return the char mapped to the given entityReference or -1.
	 */
	public char convertToCharacter(String entityReference) {
		Character referredCharacter = (Character) this.entityReferenceToCharacterMap.get(entityReference);
		if (referredCharacter != null) {
			return referredCharacter.charValue();
		}
		return CHAR_NULL;
	}

}