关于后端:RestHighLevelClient简单使用

本文转自SDK社区:sdk.cn

一、创立连贯
!ps:RestHighLevelClient是官网指定的连贯API。另外一个是TransportClient，然而TransportClient这个是曾经废除不必的，所以会在ES8.0之后齐全移除，也就是说8.0之后就无奈应用了
RestHighLevelClient的maven依赖为（应用前必须增加相应依赖）

<dependency>
<groupId>org.elasticsearch.client</groupId>
<artifactId>elasticsearch-rest-high-level-client</artifactId>
<version>7.9.2</version>
</dependency>
    <dependency>
        <groupId>org.elasticsearch</groupId>
        <artifactId>elasticsearch</artifactId>
        <version>7.9.2</version>
</dependency>

留神：以上的依赖版本能够依据你应用的ES的版本来定，向下兼容，然而无奈向上兼容

创立连贯

static String ip = "localhost";
static int port = 9200;
static RestHighLevelClient restHighLevelClient = null;
static TransportClient client = null;

static  RestHighLevelClient initClient(){
    //这里的RestClient.builder(new HttpHost(ip,port),.........)反对多个httphost连贯，也就是反对连贯多个elasticsearch
    restHighLevelClient = new RestHighLevelClient(RestClient.builder(new HttpHost(ip,port)));
}

static Connection getInstance(){
    synchronized (ElasticSearchFactory.class){
        if (restHighLevelClient == null){
         restHighLevelClient  =   initClient();
        }
    }
    return connection;
}

RestHighLevelClient 反对对ES的增删改查、批量操作
新增：

    public static  void creatIndex(String json){
    IndexRequest indexRequest = new IndexRequest("test_index","String");
    indexRequest.source(json, XContentType.JSON);//这里的json为存入ES的文档内容
    try {
        restHighLevelClient.index(indexRequest, RequestOptions.DEFAULT);//RequestOptions在新办法中必须抉择
    } catch (IOException e) {
        e.printStackTrace();
    }
}

查问：
查问反对间接查问和条件查问，因为ES是依据索引、文档类型和文档ID确定一个惟一的文档的，所以间接查问必须要有索引和类型还有ID

public static Map<String, Object> getIndex(String indexName,String type,String id){
    GetRequest request = new GetRequest(indexName);
    //SearchRequest searchRequest = new SearchRequest(indexName);
    try {
        GetResponse search = restHighLevelClient.get(request, RequestOptions.DEFAULT);
        Map<String, Object> source = search.getSource();
        return source;
    } catch (IOException e) {
        e.printStackTrace();
    }
    return new HashMap<>();
}

条件查问：
条件查问反对所有的ES的查问规定

public static Map<String, Object> searchIndex(String indexName){
    //GetRequest request = new GetRequest(indexName);
    //SearchRequest searchRequest = new SearchRequest(indexName);
    QueryBuilder queryBuilders = QueryBuilders.boolQuery().filter(
            QueryBuilders.termQuery("queryKey","吱吱吱ZZZ")
    );
    SearchRequest searchRequest = new SearchRequest();
    //searchRequest.indices("posts");这里能够设计GEET或者POST
    SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
    // searchSourceBuilder.sort(new ScoreSortBuilder().order(SortOrder.DESC));反对按评分排序，评分是指分词之后获得的文档类似度评分
    searchSourceBuilder.query(QueryBuilders.boolQuery().filter(QueryBuilders.termQuery("queryKey.keyword","吱吱吱ZZZ")));
    searchRequest.source(searchSourceBuilder);
    try {
        SearchResponse search = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);
        SearchHit[] hits = search.getHits().getHits();
        for (SearchHit searchHit : hits){
            Map<String, Object> sourceAsMap = searchHit.getSourceAsMap();
            System.out.println("source : {}" + sourceAsMap.toString());
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
    return new HashMap<>();
}

批改：
ps:ES中其实并不存在真正意义上的批改，其实是进行的文档笼罩，先将原文档查出来标记删除，而后在原文档的根底上增加上批改造成一份新文档，存入ES中，之后再将打上删除标记的文档删除。

public static void updateIndex(String indexName, String type, String id, String json){
    UpdateRequest request = new UpdateRequest(indexName, type, id);

    request.doc(json, XContentType.JSON);
    try {
        UpdateResponse updateResponse = restHighLevelClient.update(request,RequestOptions.DEFAULT);
    } catch (IOException e) {
        e.printStackTrace();
    }
}

删除:

public static void deleteIndex(String indexName, String type, String id){
    DeleteRequest request = new DeleteRequest(indexName,type,id);
    try {
        restHighLevelClient.delete(request,RequestOptions.DEFAULT);
    } catch (IOException e) {
        e.printStackTrace();
    }
}

bulk操作，bulk操作相当于批处理，可能在一次操作中解决一批数据，同时可能同时解决，增删改操作

  public static void bulkIndex(){
        BulkRequest request = new BulkRequest();
        String jsonString="{\n" +
                "\t\"databaseId\": \"謝謝謝謝謝謝\",\n" +
                "\t\"databaseType\": \"嘻嘻嘻\",\n" +
                "\t\"queryKey\":\"吱吱吱ZZZ\"\n" +
                "}\n";
    UUID uuid = UUID.randomUUID();
    request.add(new IndexRequest("test_index", "String", uuid.toString())
                .source(jsonString,XContentType.JSON));
        String updateJson="{\n" +
                "  \"queryKey\":\"吱吱吱ZZZ\"\n" +
                "}";
        request.add(new UpdateRequest("test_index", "String", uuid.toString())
                .doc(updateJson,XContentType.JSON));
        request.add(new DeleteRequest("test_index", "String", uuid.toString()));

    try {
        restHighLevelClient.bulk(request, RequestOptions.DEFAULT);
    } catch (IOException e) {
        e.printStackTrace();
    }
}

执行ES-DSL

String json = "{\"bool\":{\"filter\":[{\"term\":{\"queryKey.keyword\":\"吱吱吱ZZZ\"}}]}}";
String index= "test_index";
public static void wapQuerty(String json,String index){
    WrapperQueryBuilder queryBuilder = new WrapperQueryBuilder(json);
    SearchRequest searchRequest = new SearchRequest();
    SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
    searchSourceBuilder.query(queryBuilder);
    searchRequest.source(searchSourceBuilder).indices(index);
    try {
        SearchResponse search = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);
        SearchHit[] hits = search.getHits().getHits();
        for (SearchHit searchHit : hits){
            Map<String, Object> sourceAsMap = searchHit.getSourceAsMap();
            String id = searchHit.getId();
            System.out.println("id:"+id);
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}