isolatin1accentfilter.java

一套java版本的搜索引擎源码

package org.apache.lucene.analysis;

/**
 * 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.
 */

/**
 * A filter that replaces accented characters in the ISO Latin 1 character set 
 * (ISO-8859-1) by their unaccented equivalent. The case will not be altered.
 * <p>
 * For instance, '&agrave;' will be replaced by 'a'.
 * <p>
 */
public class ISOLatin1AccentFilter extends TokenFilter {
	public ISOLatin1AccentFilter(TokenStream input) {
		super(input);
	}

	public final Token next() throws java.io.IOException {
		final Token t = input.next();
    if (t != null)
      t.setTermText(removeAccents(t.termText()));
    return t;
	}

	/**
	 * To replace accented characters in a String by unaccented equivalents.
	 */
	public final static String removeAccents(String input) {
		final StringBuffer output = new StringBuffer();
		for (int i = 0; i < input.length(); i++) {
			switch (input.charAt(i)) {
				case '\u00C0' : // À
				case '\u00C1' : // Á
				case '\u00C2' : // Â
				case '\u00C3' : // Ã
				case '\u00C4' : // Ä
				case '\u00C5' : // Å
					output.append("A");
					break;
				case '\u00C6' : // Æ
					output.append("AE");
					break;
				case '\u00C7' : // Ç
					output.append("C");
					break;
				case '\u00C8' : // È
				case '\u00C9' : // É
				case '\u00CA' : // Ê
				case '\u00CB' : // Ë
					output.append("E");
					break;
				case '\u00CC' : // Ì
				case '\u00CD' : // Í
				case '\u00CE' : // Î
				case '\u00CF' : // Ï
					output.append("I");
					break;
				case '\u00D0' : // Ð
					output.append("D");
					break;
				case '\u00D1' : // Ñ
					output.append("N");
					break;
				case '\u00D2' : // Ò
				case '\u00D3' : // Ó
				case '\u00D4' : // Ô
				case '\u00D5' : // Õ
				case '\u00D6' : // Ö
				case '\u00D8' : // Ø
					output.append("O");
					break;
				case '\u0152' : // Œ
					output.append("OE");
					break;
				case '\u00DE' : // Þ
					output.append("TH");
					break;
				case '\u00D9' : // Ù
				case '\u00DA' : // Ú
				case '\u00DB' : // Û
				case '\u00DC' : // Ü
					output.append("U");
					break;
				case '\u00DD' : // Ý
				case '\u0178' : // Ÿ
					output.append("Y");
					break;
				case '\u00E0' : // à
				case '\u00E1' : // á
				case '\u00E2' : // â
				case '\u00E3' : // ã
				case '\u00E4' : // ä
				case '\u00E5' : // å
					output.append("a");
					break;
				case '\u00E6' : // æ
					output.append("ae");
					break;
				case '\u00E7' : // ç
					output.append("c");
					break;
				case '\u00E8' : // è
				case '\u00E9' : // é
				case '\u00EA' : // ê
				case '\u00EB' : // ë
					output.append("e");
					break;
				case '\u00EC' : // ì
				case '\u00ED' : // í
				case '\u00EE' : // î
				case '\u00EF' : // ï
					output.append("i");
					break;
				case '\u00F0' : // ð
					output.append("d");
					break;
				case '\u00F1' : // ñ
					output.append("n");
					break;
				case '\u00F2' : // ò
				case '\u00F3' : // ó
				case '\u00F4' : // ô
				case '\u00F5' : // õ
				case '\u00F6' : // ö
				case '\u00F8' : // ø
					output.append("o");
					break;
				case '\u0153' : // œ
					output.append("oe");
					break;
				case '\u00DF' : // ß
					output.append("ss");
					break;
				case '\u00FE' : // þ
					output.append("th");
					break;
				case '\u00F9' : // ù
				case '\u00FA' : // ú
				case '\u00FB' : // û
				case '\u00FC' : // ü
					output.append("u");
					break;
				case '\u00FD' : // ý
				case '\u00FF' : // ÿ
					output.append("y");
					break;
				default :
					output.append(input.charAt(i));
					break;
			}
		}
		return output.toString();
	}
}