一、功能需求

当我们用ES查询到结果后，想对命中关键词的实体的多个字段自动高亮，应该如何实现呢？

需要实现这个功能,大概分为以下几个步骤:

二、实现步骤

1. 构造查询方法，设置高亮(SearchHits方法)

   
       /**
        * 查询条件构造方法
        *
        * @param indices 索引名称(需要从那个索引当中查询)
        * @param req     查询条件
        * @param fields  查询的文档(对应数据库的字段)
        * @return SearchHit
        */
       public SearchHits queryBuilder(String indices, SearchREQ req, String[] fields) throws IOException {
           SearchSourceBuilder builder = new SearchSourceBuilder();
           BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();
           HighlightBuilder highlightBuilder = new HighlightBuilder();
   
           //设置分页
           if (req.getCurrent() > 0) {
               builder.from((int) req.getCurrent());
           }
           if (req.getSize() > 0) {
               builder.size((int) req.getSize());
           }
   
           //设置高亮
           highlightBuilder.field("*"); //所有的字段都高亮
           highlightBuilder.requireFieldMatch(false);//如果要多个字段高亮,这项要为false
           highlightBuilder.preTags("<font color='red'>").postTags("</font'>")
                           .fragmentSize(800000)//下面这两项,如果你要高亮如文字内容等有很多字的字段,必须配置,不然会导致高亮不全,文章内容缺失等;  最大高亮分片数
                           .numOfFragments(0);//从第一个分片获取高亮片段
           builder.highlighter(highlightBuilder);
   
   		//构建查询条件
           if (StringUtils.isNotEmpty(req.getUserId())) {
               boolQueryBuilder.must(QueryBuilders.matchQuery("userId", req.getUserId()));
           }
   		//模糊查询
           boolQueryBuilder.should(QueryBuilders.multiMatchQuery("*" + req.getText() + "*", fields));
           //对查询结果进行排序
           builder.query(boolQueryBuilder).sort("createDate", SortOrder.DESC);
   
           SearchRequest searchRequest = new SearchRequest(indices);
           searchRequest.source(builder);
           SearchResponse searchResponse = levelClientTests.search(searchRequest, RequestOptions.DEFAULT);
           return searchResponse.getHits();
       }
   
   

2. 调用查询方法，查询结果(findObject方法)

   
      public Result findObject(SearchREQ req) throws IOException, 
             NoSuchFieldException {
           if (StringUtils.isEmpty(req.getText())) {
               return Result.error("查找内容不能为空");
           }
           List<Object> resultList = null;
           Map<Object, Object> resultMap = new HashMap<>();
           SearchHits hits;
           String indices = "mcb_article";
           String[] fields = {"summary", "title", "mdContent"};
           hits = queryBuilder(indices, req, fields);
           Article article = null;
           resultList = new ArrayList<>();
           //遍历查询结果并接收
            for (SearchHit searchHit : hits) {
                   article = (Article) replaceAttr(searchHit, fields, indices);
                   if (article != null) {
                       resultList.add(article);
                   }
               }
       }
   

3. 使用工具替换实体的属性值(replaceAttr方法)

   
      /**
        * 替换高亮属性
        *
        * @param searchHit 查询结果
        * @param attrs 字段名
        * @return
        * @throws JsonProcessingException
        * @throws NoSuchFieldException
        */
       private Object replaceAttr(SearchHit searchHit, String[] attrs) throws JsonProcessingException, NoSuchFieldException {
           
           ObjectMapper objectMapper = new ObjectMapper();
           EntityUtil util = new EntityUtil();
           Object o = null;
           Article article = new Article();
   
           for (String field : attrs) {
               Map<String, HighlightField> highlightFields = searchHit.getHighlightFields();
               HighlightField hField = highlightFields.get(field);
               if (hField != null) {
                   //替换高亮字段
                   Text[] fragments = hField.fragments();
                   StringBuilder text = new StringBuilder();
                   for (Text textGet : fragments) {
                       text.append(textGet);
                   }
                       //对象的值只能读一次,否则会被覆盖
                   if (article.getId() == null) {
                       article = objectMapper.readValue(searchHit.
                                 getSourceAsString(), article.getClass());
                   }
                     //设置对象的属性值
                  util.setValue(article, Article.class,field,
                        Article.class.getDeclaredField(field).getType(),text.toString());
                       o = article;
                       continue;
                   }
           }
          return o;
       }
   

4. 设置对象的属性值()

   
   /**
    * 实体工具
    * @author MyLover
    * @date 2022.2.6
    * @version 1.0.0
    */
   public class EntityUtil {
   
       /**
        * 设置对象对应的属性值
        * @param obj 传入的对象
        * @param clazz 传入对象的类
        * @param filedName 需要设置的字段名
        * @param typeClass 字段的类型
        * @param value 需要设置的值
        *  实例:  设置Article的id属性值为1
        *  Article article = new Article();
        *  String field = "id";
        *  setValue(article_es1,Article_ES.class,field,
        *  Article.class.getDeclaredField(field).getType(),"1");
        */
       public void setValue(Object obj, Class<?> clazz, String filedName, Class<?> typeClass, Object value) {
           String methodName = "set" + filedName.substring(0, 1)
               .toUpperCase() + filedName.substring(1);
           try {
               Method method = clazz.getDeclaredMethod(methodName, typeClass);
               method.invoke(obj, getClassTypeValue(typeClass, value));
           } catch (Exception ex) {
               ex.printStackTrace();
           }
       }
       /**
        * 根据属性，获取对象的属性值, 例如: getGetMethod(Article,id)
        * @param ob   对象
        * @param name 属性名
        */
       public  Object getGetMethod(Object ob, String name) throws Exception {
           Method[] m = ob.getClass().getMethods();
           for (Method method : m) {
               if (("get" + name).toLowerCase().equals(method.getName().toLowerCase())) {
                   return method.invoke(ob);
               }
           }
           return null;
       }
   
       private  Object getClassTypeValue(Class<?> typeClass, Object value) {
           if (typeClass == int.class || value instanceof Integer) {
               if (null == value) {
                   return 0;
               }
               return value;
           } else if (typeClass == short.class) {
               if (null == value) {
                   return 0;
               }
               return value;
           } else if (typeClass == byte.class) {
               if (null == value) {
                   return 0;
               }
               return value;
           } else if (typeClass == double.class) {
               if (null == value) {
                   return 0;
               }
               return value;
           } else if (typeClass == long.class) {
               if (null == value) {
                   return 0;
               }
               return value;
           } else if (typeClass == String.class) {
               if (null == value) {
                   return "";
               }
               return value;
           } else if (typeClass == boolean.class) {
               if (null == value) {
                   return true;
               }
               return value;
           } else if (typeClass == BigDecimal.class) {
               if (null == value) {
                   return new BigDecimal(0);
               }
               return new BigDecimal(value + "");
           } else {
               return typeClass.cast(value);
           }
       }
   }