分页查询

【数据分页】

       MySql =====〉limit

       Oracle=====〉RowNum

       MsSql=====〉in子查询

【Lucene】

       3.5前 =====〉再查询

       3.5后=====〉searchAfter()

【分页】

1) 分页的参数

     每页记录数

     当前页索引

2) 再查询

    /**
     * 通过再搜索的方式进行分页
     * @param key                ：查询关键字
     * @param pageIndex    ：当前页索引
     * @param pageSize        ：每页记录数
     */
    public void searchAgain(String key, int pageIndex,int pageSize){
        IndexReader reader= null;
        IndexSearcher searcher = null;
        
        try{
            //获取Reader
            reader = util.getReader(getDirectory(path));
                
            //获取Searcher
            searcher = new IndexSearcher(reader);    
            
            //获取Query
            QueryParser parser = new QueryParser(version,"content",new StandardAnalyzer(version));    
            Query query = parser.parse(key);
            
            //获取TopDocs
            TopDocs td =     searcher.search(query, 500);
            System.out.println("总结查询到" + td.totalHits + "条数据");
            
            //获取ScoreDoc
            ScoreDoc[] sds = td.scoreDocs;
            
            //显示条目
            //起始索引
            int start = (pageIndex -1) * pageSize;
            //结束索引
            int end = pageSize * pageIndex;
            
            //从查询结果中进行截取
            for(int i = start;i<end;i++){
                Document doc = searcher.doc(sds[i].doc);
                
                System.out.println(i + "、" + doc.get("filename") + " == " + doc.get("size") + " == " + doc.get("modifydate") + "  == " + doc.get("path"));
            }
        }
        catch(Exception e){
            e.printStackTrace();
        }
        finally{
            try {
                searcher.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        System.out.println("再查询结束");
    }

3) searchAgain()

获取上一页的最后一个元素

    /**
     * 获取上一页的最后一个元素
     * @param query
     * @param searcher
     * @param index
     * @param size
     * @return
     */
    public ScoreDoc getLastDoc(Query query, IndexSearcher searcher, int index, int size){
        if(index == 1)
            return null;
        
        //当前页的第一个条目的索引（id）
        int  total = (index - 1) * size;
    
        try {
            //查询上一页的所有条目
            TopDocs td = searcher.search(query, total);
            
            //返回最后一个元素
            return td.scoreDocs[total-1];
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            return null;
        }
    }

 使用searchAfter()实现搜索

    /**
     * 使用searchAfter()实现搜索
     * @param key
     */
    public void searchByAfter(String key,int pageIndex,int pageSize){
        IndexReader reader= null;
        IndexSearcher searcher = null;
        
        try{
            //获取Reader
            reader = util.getReader(getDirectory(path));
                
            //获取Searcher
            searcher = new IndexSearcher(reader);    
            
            //获取Query
            QueryParser parser = new QueryParser(version,"content",new StandardAnalyzer(version));    
            Query query = parser.parse(key);
            
            ScoreDoc after = getLastDoc(query,searcher,pageIndex, pageSize);
            TopDocs td = searcher.searchAfter(after, query, pageSize);
            ScoreDoc[] sds = td.scoreDocs;
            
            /*
            //获取TopDocs
            TopDocs td =     searcher.search(query, 500);
            System.out.println("总结查询到" + td.totalHits + "条数据");
                        
            //获取ScoreDoc
            ScoreDoc[] sds = td.scoreDocs;
            //查询第1页
            //searchAfter(下一页的第一个条目)
            //td = searcher.searchAfter(null,query,10);
            //查询第2页
            td = searcher.searchAfter(sds[10],query, 10);
            
            //获取ScoreDoc
            sds = td.scoreDocs;
            */
            //从查询结果中进行截取
            int i = 1;
            for(ScoreDoc sd : sds){
                Document doc = searcher.doc(sd.doc);
                
                System.out.println(i + "、" + doc.get("filename") + " == " + doc.get("size") + " == " + doc.get("modifydate") + "  == " + doc.get("path"));
                i++;
            }
        }
        catch(Exception e){
            e.printStackTrace();
        }
        finally{
            try {
                searcher.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        System.out.println("再查询结束");
    }