spring-data-elasticsearch分页查询

我会带着你远行 2022-05-29 07:05 832阅读 0赞

@Test
    	public void testQueryPage() {
    		QueryBuilder orderQuery = QueryBuilders.boolQuery()
    				.must(QueryBuilders.matchQuery("orderType", "RO"));
    		Page<OrderItem> page = orderRepository.search(orderQuery, PageRequest.of(0, 1));
    		System.out.println(page);
    
    		page = orderRepository.search(orderQuery, PageRequest.of(1, 1));
    		System.out.println(page);
    	}

附录：

1、从名字就能看出来，QueryBuilder主要用来构建查询条件、过滤条件，SortBuilder主要是构建排序。

譬如，我们要查询距离某个位置100米范围内的所有人、并且按照距离远近进行排序：

double lat = 39.929986;  
    	double lon = 116.395645;  
      
            Long nowTime = System.currentTimeMillis();  
            //查询某经纬度100米范围内  
            GeoDistanceQueryBuilder builder = QueryBuilders.geoDistanceQuery("address").point(lat, lon)  
                    .distance(100, DistanceUnit.METERS);  
      
            GeoDistanceSortBuilder sortBuilder = SortBuilders.geoDistanceSort("address")  
                    .point(lat, lon)  
                    .unit(DistanceUnit.METERS)  
                    .order(SortOrder.ASC);  
      
            Pageable pageable = new PageRequest(0, 50);  
      
            NativeSearchQueryBuilder builder1 = new NativeSearchQueryBuilder().withFilter(builder).withSort(sortBuilder).withPageable(pageable);  
    	SearchQuery searchQuery = builder1.build();

2、

# 限定查询结果集大小 #

Spring Data允许开发者使用first和top关键字对返回的查询结果集大小进行限定。fisrt和top需要跟着一个代表返回的结果集的最大大小的数字。如果没有跟着一个数字，那么返回的结果集大小默认为1。

Example 8.Limiting the result size of query with Top and First(利用first和top限制返回的结果集大小)

User findFirstByOrderByLastnameAsc(); User findTopByOrderByAgeDesc(); Page<User> queryFirst10ByLastname(String lastname, Pageable pageable); Slice<User> findTop3ByLastname(String lastname, Pageable pageable); List<User> findFirst10ByLastname(String lastname, Sort sort); List<User> findTop10ByLastname(String lastname, Pageable pageable);

限制结果集的表达式还支持Distinct关键字。并且，当返回的结果集大小限制为1时，Spring Data支持将返回结果包装到Optional(java 8新增，这是一个可以为null的容器对象。如果值存在则isPresent()方法会返回true，调用get()方法会返回该对象)之中，例子如下:

Optional<User> findFirstByOrderByLastnameAsc();

在查询用page和slice来进行分页查询的情况下，同样可以使用first和top来对结果集大小进行限制。

注意，如果在使用Sort参数对查询结果进行排序的基础上加上对结果集大小的限制，就可以轻易的获得最大的K个元素或最小的K个元素。

3、

# 利用Scan和Scroll处理大结果集 #

Elasticsearch在处理大结果集时可以使用scan和scroll。在Spring Data Elasticsearch中，可以向下面那样使用ElasticsearchTemplate来使用scan和scroll处理大结果集。

@Test  
        public void shouldReturnResultsWithScanAndScrollForGivenCriteriaQuery() {  
            //given  
            List<IndexQuery> entities = createSampleEntitiesWithMessage("Test message", 30);  
            // when  
            elasticsearchTemplate.bulkIndex(entities);  
            elasticsearchTemplate.refresh(SampleEntity.class);  
            // then  
      
            CriteriaQuery criteriaQuery = new CriteriaQuery(new Criteria());  
            criteriaQuery.addIndices(INDEX_NAME);  
            criteriaQuery.addTypes(TYPE_NAME);  
            criteriaQuery.setPageable(new PageRequest(0, 10));  
      
            String scrollId = elasticsearchTemplate.scan(criteriaQuery, 1000, false);  
            List<SampleEntity> sampleEntities = new ArrayList<SampleEntity>();  
            boolean hasRecords = true;  
            while (hasRecords) {  
                Page<SampleEntity> page = elasticsearchTemplate.scroll(scrollId, 5000L, SampleEntity.class);  
                if (page.hasContent()) {  
                    sampleEntities.addAll(page.getContent());  
                } else {  
                    hasRecords = false;  
                }  
            }  
            elasticsearchTemplate.clearScroll(scrollId);  
            assertThat(sampleEntities.size(), is(equalTo(30)));  
        }

SearchQuery searchQuery = new NativeSearchQueryBuilder()
        .withQuery(matchAllQuery())
        .withIndices("test-index")
        .withTypes("test-type")
        .withPageable(new PageRequest(0,1))
        .build();
    String scrollId = elasticsearchTemplate.scan(searchQuery,1000,false);
    List<SampleEntity> sampleEntities = new ArrayList<SampleEntity>();
    boolean hasRecords = true;
    while (hasRecords){
        Page<SampleEntity> page = elasticsearchTemplate.scroll(scrollId, 5000L , new ResultsMapper<SampleEntity>()
        {
            @Override
            public Page<SampleEntity> mapResults(SearchResponse response) {
                List<SampleEntity> chunk = new ArrayList<SampleEntity>();
                for(SearchHit searchHit : response.getHits()){
                    if(response.getHits().getHits().length <= 0) {
                        return null;
                    }
                    SampleEntity user = new SampleEntity();
                    user.setId(searchHit.getId());
                    user.setMessage((String)searchHit.getSource().get("message"));
                    chunk.add(user);
                }
                return new PageImpl<SampleEntity>(chunk);
            }
        });
        if(page != null) {
            sampleEntities.addAll(page.getContent());
            hasRecords = page.hasNextPage();
        }
        else{
            hasRecords = false;
        }
        }
    }