RestHighLevelClient一次查詢多個條件

就像bulk在多文檔索引時提高效率一樣，msearch也能提升多個查詢的執行效率，這裏主要考慮到網絡消耗，使用search查詢可能要循環執行N遍，但是使用msearch一次從客戶端一次客戶請求即可。下面給出實例代碼：

	@Test
	public void testMultiSearch(){
		MultiSearchRequest request = new MultiSearchRequest();    
		SearchRequest firstSearchRequest = new SearchRequest();   
		SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
		searchSourceBuilder.query(QueryBuilders.matchQuery("cityId", "410500"));
		firstSearchRequest.source(searchSourceBuilder);
		firstSearchRequest.indices("sub_bank1031");
		request.add(firstSearchRequest);                          
		SearchRequest secondSearchRequest = new SearchRequest();  
		searchSourceBuilder = new SearchSourceBuilder();
		searchSourceBuilder.query(QueryBuilders.matchQuery("cityId", "511000"));
		secondSearchRequest.source(searchSourceBuilder);
		secondSearchRequest.indices("sub_bank1031");
		request.add(secondSearchRequest);
        try {
        	MultiSearchResponse response = highLevelClient.msearch(request, RequestOptions.DEFAULT);
        	response.forEach(t->{
        		SearchResponse resp = t.getResponse();
        		
                Arrays.stream(resp.getHits().getHits())
                .forEach(i -> {
                	System.out.println(i.getId());
                    System.out.println(i.getIndex());
                    System.out.println(i.getSourceAsString());
                    System.out.println(i.getShard());
                });
                System.out.println(resp.getHits().totalHits);
        	});
        } catch (IOException e) {
            e.printStackTrace();
        }		
	}

pom中依賴爲：

          <dependency>
            <groupId>org.elasticsearch</groupId>
            <artifactId>elasticsearch</artifactId>
            <version>6.8.0</version>
        </dependency>
        <!-- elasticsearch high level -->    
        <dependency>
            <groupId>org.elasticsearch.client</groupId>
            <artifactId>elasticsearch-rest-high-level-client</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.elasticsearch</groupId>
                    <artifactId>elasticsearch</artifactId>                
                </exclusion>
            </exclusions>
            <version>6.8.0</version>
        </dependency>