我有一个描述树结构的分类索引。执行查询时,我想获取多个类别的命中数(不一定在树的同一级别)。例如,给定以下路径列表:
[Root/Cat1, Root/Cat1/Cat12, Root/Cat3]
我想获得这三个类别中每一个的点击数。
我一直在寻找解决方案,我知道可以发出树请求,然后通过调用获取结果.getSubResults()
(如API中所述)。但是我没有找到任何示例,我真的不知道如何实现它。到目前为止,我有以下几点:
// Build query
Query query = extendQuery(queryGenerator.generateQuery(resource));
// Set the number of top results
TopScoreDocCollector tdc = TopScoreDocCollector.create(numTopDocuments, true);
// Set a faceted search
FacetSearchParams facetSearchParams = new FacetSearchParams();
// Search at level of the category in interests
CountFacetRequest facetRequest = new CountFacetRequest(new CategoryPath("Top", '/'), numTopCategories);
facetRequest.setResultMode(ResultMode.PER_NODE_IN_TREE);
facetSearchParams.addFacetRequest(facetRequest);
// To collect the number of hits per facet
FacetsCollector facetsCollector =
new FacetsCollector(facetSearchParams, documentReader, taxonomyReader);
try {
// Collect the number of hits per facet
documentSearcher
.search(query, MultiCollector.wrap(tdc, facetsCollector));
for (FacetResult res : facetsCollector.getFacetResults()){
//this is the top lvl facet
FacetResultNode toplvl = res.getFacetResultNode();
System.out.println(toplvl.getLabel() + " (" + toplvl.getValue() + ")");
for (FacetResultNode secondlvl : toplvl.getSubResults()) {
//second lvl facet categories
System.out.println(" " + secondlvl.getLabel().getComponent(1)
+ " (" + secondlvl.getValue() + ")");
for (FacetResultNode thirdlvl : secondlvl.getSubResults()) {
//second lvl facet categories
System.out.println(" " + thirdlvl.getLabel().getComponent(2)
+ " (" + thirdlvl.getValue() + ")");
}
}
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
但是,当我到达第三级时,我得到了空值。到底是怎么回事?
谢谢。