testgermanstemfilter.java

一套java版本的搜索引擎源码

package org.apache.lucene.analysis.de;

/**
 * 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.
 */

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.StringReader;

import junit.framework.TestCase;

import org.apache.lucene.analysis.Token;
import org.apache.lucene.analysis.standard.StandardTokenizer;

/**
 * Test the German stemmer. The stemming algorithm is known to work less 
 * than perfect, as it doesn't use any word lists with exceptions. We 
 * also check some of the cases where the algorithm is wrong.
 * 
 * @author Daniel Naber
 */
public class TestGermanStemFilter extends TestCase {

  public void testStemming() {
    try {
      // read test cases from external file:
      File dataDir = new File(System.getProperty("dataDir", "./bin"));
      File testFile = new File(dataDir, "org/apache/lucene/analysis/de/data.txt");
      FileInputStream fis = new FileInputStream(testFile);
      InputStreamReader isr = new InputStreamReader(fis, "iso-8859-1");
      BufferedReader breader = new BufferedReader(isr);
      while(true) {
        String line = breader.readLine();
        if (line == null)
          break;
        line = line.trim();
        if (line.startsWith("#") || line.equals(""))
          continue;    // ignore comments and empty lines
        String[] parts = line.split(";");
        //System.out.println(parts[0] + " -- " + parts[1]);
        check(parts[0], parts[1]);
      }
      breader.close();
      isr.close();
      fis.close();
    } catch (IOException e) {
       e.printStackTrace();
       fail();
    }
  }

  private void check(final String input, final String expected) throws IOException {
    StandardTokenizer tokenStream = new StandardTokenizer(new StringReader(input));
    GermanStemFilter filter = new GermanStemFilter(tokenStream);
    Token t = filter.next();
    if (t == null)
      fail();
    assertEquals(expected, t.termText());
    filter.close();
  }

}