lucene综合施用

lucene综合使用

I.Sorting search results

在Lucene中有两种特别的类型是用来排序的:Score和Index order

要排序结果 可以使用IndexSearcher的重载serach函数,提供一个Sort参数.看个例子.SortingExample.java

01?package?lia.advsearching;
02?
03?import?org.apache.commons.lang.StringUtils;
04?import?org.apache.lucene.document.Document;
05?import?org.apache.lucene.index.Term;
06?import?org.apache.lucene.search.Hits;
07?import?org.apache.lucene.search.IndexSearcher;
08?import?org.apache.lucene.search.Query;
09?import?org.apache.lucene.search.RangeQuery;
10?import?org.apache.lucene.search.Sort;
11?import?org.apache.lucene.search.SortField;
12?import?org.apache.lucene.store.Directory;
13?import?org.apache.lucene.store.FSDirectory;
14?
15?import?java.io.IOException;
16?import?java.text.DecimalFormat;
17?
18?public?class?SortingExample?{
19???private?Directory?directory;
20?
21???public?SortingExample(Directory?directory)?{
22?????this.directory?=?directory;
23???}
24?? // 显示搜索结果
25???public?void?displayHits(Query?query,?Sort?sort)
26???????throws?IOException?{
27?????IndexSearcher?searcher?=?new?IndexSearcher(directory);
28?
29?????Hits?hits?=?searcher.search(query,?sort);? // 安sort 来排序搜索结果
30?
31?????System.out.println("\nResults?for:?"?+
32?????????query.toString()?+?"?sorted?by?"?+?sort);? // 打印query 和sort
33?
34?????System.out.println(StringUtils.rightPad("Title",?30)?+?? // 使用StringUtils(来自Apache commons)打印结果
35?????????StringUtils.rightPad("pubmonth",?10)?+
36?????????StringUtils.center("id",?4)?+
37?????????StringUtils.center("score",?15));
38?
39?????DecimalFormat?scoreFormatter?=?new?DecimalFormat("0.######");
40?????for?(int?i?=?0;?i?<?hits.length();?i++)?{???????????????? // 打印结果
41???????Document?doc?=?hits.doc(i);
42???????System.out.println(
43???????????StringUtils.rightPad(
44???????????????StringUtils.abbreviate(doc.get("title"),?29),?30)?+
45???????????StringUtils.rightPad(doc.get("pubmonth"),?10)?+
46???????????StringUtils.center(""?+?hits.id(i),?4)?+
47???????????StringUtils.leftPad(
48???????????????scoreFormatter.format(hits.score(i)),?12));
49???????System.out.println("???"?+?doc.get("category"));
50?//??????System.out.println(searcher.explain(query,?hits.id(i)));
51?????}
52?
53?????searcher.close();
54???}
55?
56???public?static?void?main(String[]?args)?throws?Exception?{
57?????Term?earliest?=?new?Term("pubmonth",?"190001");
58?????Term?latest?=?new?Term("pubmonth",?"201012");
59?????RangeQuery?allBooks?=?new?RangeQuery(earliest,?latest,?true);???? //? query
60?
61?????String?indexDir?=?System.getProperty("index.dir");? // index的目录
62?
63?????FSDirectory?directory?=
64?????????FSDirectory.getDirectory(indexDir,?false);
65?????SortingExample?example?=?new?SortingExample(directory);
66?
67?????example.displayHits(allBooks,?Sort.RELEVANCE);? // 使用Lucene默认的排序
68?
69?????example.displayHits(allBooks,?Sort.INDEXORDER);? // 根据IndexOrder排序
70?
71?????example.displayHits(allBooks,?new?Sort("category"));? // 根据category 排序
72?
73?????example.displayHits(allBooks,?new?Sort("pubmonth",?true));? // 根据pubmonth 排序
74?
75?????example.displayHits(allBooks,
76?????????new?Sort(new?SortField[]{
77???????????new?SortField("category"),
78???????????SortField.FIELD_SCORE,
79???????????new?SortField("pubmonth",?SortField.INT,?true)
80?????????}));? ///
81?
82?
83?????example.displayHits(allBooks,?new?Sort(new?SortField[]?{SortField.FIELD_SCORE,?new?SortField("category")}));
84???}
85?}

当sort 参数是null ,new Sort(),和Sort.RELEVANCE 时,使用的是Lucene的默认排序(按照Relevance的递减排序), 默认搜索的结果如下:

先按照Score递减排序 如果Score相同则按照Docnum 递增排序.

If the order documents were indexed is relevant, you can use Sort.INDEXORDER.

下面是其输出结果:(安装ID来排序)

要利用Field排序,该field要满足第二章排序(参考我的Blog上的内容)的要求. 下面是使用category field的输出.

默认的field排序是按照自然排序,利用Sort的重载函数,提供一个reverse参数可以改变顺序.结果如下:

example.displayHits(allBooks, new Sort("pubmonth", true)); 提供了true参数.

还可以根据多个Field排序. 用法如下:

example.displayHits(allBooks,

new Sort(new SortField[]{

new SortField("category"),

SortField.FIELD_SCORE,

new SortField("pubmonth", SortField.INT, true)

}));

margin: 5pt 6