Java操作ElasticSearch（三、查询）

查询的步骤如下

1. 创建 SearchSourceBuilder 对象
2. 添加查询条件 QueryBuilders
3. 添加排序、分页等其他条件
4. 创建 SearchRequest 对象，并指定索引库名称
5. 发起请求，得到结果
6. 获取总条数
7. 获取 SearchHits 数组，并遍历
8. 获取其中的 _source，是 JSON 数据
9. 把 _source 反序列化为 User 对象

查询所有 match_all

@Test
public void test011() throws IOException {
    // 创建请求对象，用于描述本次请求语义
    SearchRequest request = new SearchRequest("user"); // 创建查询语义对象
    // 设置查询类型
    SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
    searchSourceBuilder.query(QueryBuilders.matchAllQuery());
    // 添加SearchSourceBuilder对象到SearchRequest对象中
    request.source(searchSourceBuilder);
    // 发送请求给es
    SearchResponse response = client.search(request, RequestOptions.DEFAULT);
    // 处理响应结果
    SearchHits searchHits = response.getHits();
    // 总条数
    System.out.println("命中的总条数: " + searchHits.getTotalHits().value); // 12
    // 返回数据数组
    SearchHit[] hits = searchHits.getHits();
    for (SearchHit hit : hits) {
        String sourceAsString = hit.getSourceAsString();
        User user = JSON.parseObject(sourceAsString, User.class);
        System.out.println(user);
    }
}

分词查询 match

@Test
public void test12() throws IOException {
    SearchRequest request = new SearchRequest("user");
    SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
    searchSourceBuilder.query(QueryBuilders.matchQuery("note", "唱歌表演"));
    request.source(searchSourceBuilder);
    SearchResponse response = client.search(request, RequestOptions.DEFAULT);
    SearchHits searchHits = response.getHits();
    System.out.println("命中数:" + searchHits.getTotalHits().value);
    SearchHit[] hits = searchHits.getHits();
    for (SearchHit hit : hits) {
        String sourceAsString = hit.getSourceAsString();
        User user = JSON.parseObject(sourceAsString, User.class);
        System.out.println(user);
    }
}

词条查询 term

@Test
public void test14() throws IOException {
    SearchRequest request = new SearchRequest("user");
    SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
    searchSourceBuilder.query(QueryBuilders.termQuery("gender", "女"));
    request.source(searchSourceBuilder);
    SearchResponse response = client.search(request, RequestOptions.DEFAULT);
    SearchHits searchHits = response.getHits();
    System.out.println("命中数：" + searchHits.getTotalHits());
    SearchHit[] hits = searchHits.getHits();
    for (SearchHit hit : hits) {
        String sourceAsString = hit.getSourceAsString();
        User user = JSON.parseObject(sourceAsString, User.class);
        System.out.println(user);
    }
}

范围查询 range

@Test
public void test15() throws IOException {
    SearchRequest request = new SearchRequest("user");
    SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
    RangeQueryBuilder queryBuilder = QueryBuilders.rangeQuery("age");
    // 查询年龄大于20岁 小于25岁的同学
    queryBuilder.gt(20).lt(25);
    searchSourceBuilder.query(queryBuilder);
    request.source(searchSourceBuilder);
    SearchResponse response = client.search(request, RequestOptions.DEFAULT);
    SearchHits searchHits = response.getHits();
    System.out.println("命中数:" + searchHits.getTotalHits());
    SearchHit[] hits = searchHits.getHits();
    for (SearchHit hit : hits) {
        String sourceAsString = hit.getSourceAsString();
        User user = JSON.parseObject(sourceAsString, User.class);
        System.out.println(user);
    }
}

模糊查询 fuzzy

@Test
public void test16() throws IOException {
    SearchRequest request = new SearchRequest("user");
    SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
    searchSourceBuilder.query(QueryBuilders.fuzzyQuery("note", "三"));
    request.source(searchSourceBuilder);
    SearchResponse response = client.search(request, RequestOptions.DEFAULT);
    SearchHits searchHits = response.getHits();
    System.out.println("命中数:" + searchHits.getTotalHits());
    SearchHit[] hits = searchHits.getHits();
    for (SearchHit hit : hits) {
        String sourceAsString = hit.getSourceAsString();
        User user = JSON.parseObject(sourceAsString, User.class);
        System.out.println(user);
    }
}

布尔查询 bool

@Test
public void test13() throws IOException {
    SearchRequest request = new SearchRequest("user");
    SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
    BoolQueryBuilder queryBuilder = QueryBuilders.boolQuery();
    // 添加条件
    queryBuilder.must(QueryBuilders.matchQuery("note", "Java"));
    queryBuilder.mustNot(QueryBuilders.termQuery("gender", "女"));
    searchSourceBuilder.query(queryBuilder);
    request.source(searchSourceBuilder);
    SearchResponse response = client.search(request, RequestOptions.DEFAULT);
    SearchHits searchHits = response.getHits();
    System.out.println("命中数：" + searchHits.getTotalHits());
    SearchHit[] hits = searchHits.getHits();
    for (SearchHit hit : hits) {
        String sourceAsString = hit.getSourceAsString();
        User user = JSON.parseObject(sourceAsString, User.class);
        System.out.println(user);
    }
}