这里也是排序的代码。尽管我认为考虑到城市规模而不是强制对人口进行排序，添加自定义评分会更有意义。另请注意，这使用了 FieldCache，这可能不是关于内存使用的最佳解决方案。
public class ShingleFilterTests {
private Analyzer analyzer;
private IndexSearcher searcher;
private IndexReader reader;
private QueryParser qp;
private Sort sort;
public static Analyzer createAnalyzer(final int shingles) {
return new Analyzer() {
@Override
public TokenStream tokenStream(String fieldName, Reader reader) {
TokenStream tokenizer = new WhitespaceTokenizer(reader);
tokenizer = new StopFilter(false, tokenizer, ImmutableSet.of("de", "la", "en"));
if (shingles > 0) {
tokenizer = new ShingleFilter(tokenizer, shingles);
}
return tokenizer;
}
};
}
public class PopulationComparatorSource extends FieldComparatorSource {
@Override
public FieldComparator newComparator(String fieldname, int numHits, int sortPos, boolean reversed) throws IOException {
return new PopulationComparator(fieldname, numHits);
}
private class PopulationComparator extends FieldComparator {
private final String fieldName;
private Integer[] values;
private int[] populations;
private int bottom;
public PopulationComparator(String fieldname, int numHits) {
values = new Integer[numHits];
this.fieldName = fieldname;
}
@Override
public int compare(int slot1, int slot2) {
if (values[slot1] > values[slot2]) return -1;
if (values[slot1] < values[slot2]) return 1;
return 0;
}
@Override
public void setBottom(int slot) {
bottom = values[slot];
}
@Override
public int compareBottom(int doc) throws IOException {
int value = populations[doc];
if (bottom > value) return -1;
if (bottom < value) return 1;
return 0;
}
@Override
public void copy(int slot, int doc) throws IOException {
values[slot] = populations[doc];
}
@Override
public void setNextReader(IndexReader reader, int docBase) throws IOException {
/* XXX uses field cache */
populations = FieldCache.DEFAULT.getInts(reader, "population");
}
@Override
public Comparable value(int slot) {
return values[slot];
}
}
}
@Before
public void setUp() throws Exception {
Directory dir = new RAMDirectory();
analyzer = createAnalyzer(3);
IndexWriter writer = new IndexWriter(dir, analyzer, IndexWriter.MaxFieldLength.UNLIMITED);
ImmutableList<String> cities = ImmutableList.of("Bosc de Planavilla", "Planavilla", "Bosc de la Planassa",
"Bosc de Plana en Blanca");
ImmutableList<Integer> populations = ImmutableList.of(5000, 20000, 1000, 100000);
for (int id = 0; id < cities.size(); id++) {
Document doc = new Document();
doc.add(new Field("id", String.valueOf(id), Field.Store.YES, Field.Index.NOT_ANALYZED));
doc.add(new Field("city", cities.get(id), Field.Store.YES, Field.Index.ANALYZED));
doc.add(new Field("population", String.valueOf(populations.get(id)),
Field.Store.YES, Field.Index.NOT_ANALYZED));
writer.addDocument(doc);
}
writer.close();
qp = new QueryParser(Version.LUCENE_30, "city", createAnalyzer(0));
sort = new Sort(new SortField("population", new PopulationComparatorSource()));
searcher = new IndexSearcher(dir);
searcher.setDefaultFieldSortScoring(true, true);
reader = searcher.getIndexReader();
}
@After
public void tearDown() throws Exception {
searcher.close();
}
@Test
public void testShingleFilter() throws Exception {
System.out.println("shingle filter");
printSearch("city:\"Bosc de Planavilla\"");
printSearch("city:Planavilla");
printSearch("city:Bosc");
}
private void printSearch(String query) throws ParseException, IOException {
Query q = qp.parse(query);
System.out.println("query " + q);
TopDocs hits = searcher.search(q, null, 4, sort);
System.out.println("results " + hits.totalHits);
int i = 1;
for (ScoreDoc dc : hits.scoreDocs) {
Document doc = reader.document(dc.doc);
System.out.println(i++ + ". " + dc + " \"" + doc.get("city") + "\" population: " + doc.get("population"));
}
System.out.println();
}
}
这给出了以下结果：
query city:"Bosc Planavilla"
results 1
1. doc=0 score=1.143841[5000] "Bosc de Planavilla" population: 5000
query city:Planavilla
results 2
1. doc=1 score=1.287682[20000] "Planavilla" population: 20000
2. doc=0 score=0.643841[5000] "Bosc de Planavilla" population: 5000
query city:Bosc
results 3
1. doc=3 score=0.375[100000] "Bosc de Plana en Blanca" population: 100000
2. doc=0 score=0.5[5000] "Bosc de Planavilla" population: 5000
3. doc=2 score=0.5[1000] "Bosc de la Planassa" population: 1000