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深入了解Elasticsearch的CRUD：ES Java API之增删改查

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发表于 2023-6-2 16:19:47 | 显示全部楼层 |阅读模式
在基本了解并在Kibana Dev Tools控制台操作Elasticsearch的查询语法之后，是时候在实际应用中使用ES了。那么怎么在Java中使用ES呢？
可以有下面几种方式来实现：

  • Transport Client
  • Java High Level REST Client
  • Spring Data Elasticsearch
TransportClient 可用于老版本的Elasticsearch；新版本建议使用 Java High Level REST Client （向下兼容）；当然还可以使用Spring Data提供的 Spring Data Elasticsearch 。
本文先只介绍一下 Transport Client API，后面慢慢来 REST Client 和 Spring Data Elasticsearch 。
Transport Client

注意：在7.0.0中弃用。不推荐使用TransportClient，而推荐使用Java High Level REST Client，并将在Elasticsearch 8.0中将其删除。
Elasticsearch 8.x版本将会删除 TransportClient 。这里为什么还要介绍一下它的API呢？毕竟有些老铁用的还是以前的版本，而且API很多地方是相通的，那就多学习一点吧！
引入jar包

<pre class="prettyprint hljs xml" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, "Courier New", monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;"><dependency>
    <groupId>org.elasticsearch.client</groupId>
    <artifactId>transport</artifactId>
    <version>7.9.0</version>
</dependency>注意版本号，一定要和你安装的Elasticsearch的版本号一致。
创建到ES的连接

必须得先连接到ES才能进行一系列的API测试，连接的代码如下：
<pre class="prettyprint hljs go" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, "Courier New", monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">// 创建连接
TransportClient client = new PreBuiltTransportClient(Settings.EMPTY)
        .addTransportAddress(
                new TransportAddress(
                        InetAddress.getByName("localhost"), 9300));
//一系列操作...

//关闭连接
client.close();

可以看到， TransportClient 是deprecated，弃用了，我用的是ES 7.9版本，它在7.0.0中被弃用。
注意：

  • InetAddress.getByName("localhost"), 9300) 这里绑定的端口 9300 是通讯端口，不是服务端口（服务端口是9200）
  • 如果使用与 Elasticsearch 不同的集群名称，则必须设置集群名称：
<pre class="prettyprint hljs dockerfile" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, "Courier New", monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">Settings settings = Settings.builder()
        .put("cluster.name", "myClusterName").build();
TransportClient client = new PreBuiltTransportClient(settings);

//Add transport addresses and do something with the client... 比如我的：


单节点ES默认的集群名称就是 elasticsearch 。
Index API

索引API允许将输入的JSON文档索引到特定索引中并使之可搜索。
生成JSON文档

生成JSON文档有很多种方法，比如：

  • 手动构造
<pre class="prettyprint hljs vbscript" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, "Courier New", monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">String json = "{" +
    "\"user\":\"kimchy\"," +
    "\"postDate\":\"2013-01-30\"," +
    "\"message\":\"trying out Elasticsearch\"" +
"}";

  • 使用Map
<pre class="prettyprint hljs javascript" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, "Courier New", monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">Map<String, Object> json = new HashMap<String, Object>();
json.put("user","kimchy");
json.put("postDate",new Date());
json.put("message","trying out Elasticsearch");Map是一个key：values对集合。它可以表示一个JSON结构。

  • Jackson
可以使用Jackson将bean序列化为JSON。
<pre class="prettyprint hljs verilog" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, "Courier New", monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">import com.fasterxml.jackson.databind.*;

// instance a json mapper
ObjectMapper mapper = new ObjectMapper(); // create once, reuse

// generate json
byte[] json = mapper.writeValueAsBytes(yourbeaninstance);

  • fastjson
com.alibaba.fastjson.JSONObject
它的转换方法，包括Java对象转成JSON串、JSON对象，JSON串转成java对象、JSON对象，JSON对象转换Java对象、JSON串等。
<pre class="prettyprint hljs xquery" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, "Courier New", monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">String stuString = "{\"age\":2,\"name\":\"公众号行百里er\",\"sex\":\"m\"}";

//JSON字符串转换成JSON对象
JSONObject jsonObject1 = JSONObject.parseObject(stuString);

  • 等等
当然，Elasticsearch 也提供了内置的帮助器以生成JSON内容：
<pre class="prettyprint hljs vbscript" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, "Courier New", monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">XContentBuilder builder = jsonBuilder()
    .startObject()
        .field("user", "kimchy")
        .field("postDate", new Date())
        .field("message", "trying out Elasticsearch")
    .endObject()增删改查API

Create 创建索引、文档相关API

向索引添加文档，如果索引不存在，则该API会自动给我们创建索引
<pre class="prettyprint hljs dart" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, "Courier New", monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">@Test
@SneakyThrows
void esCRUD() {
    // 创建连接
    TransportClient client = new PreBuiltTransportClient(Settings.EMPTY)
            .addTransportAddress(
                    new TransportAddress(
                            InetAddress.getByName("localhost"), 9300));

    //增
    //create(client);
    //查
    //get(client);
    //getAll(client);
    //改
    //update(client);
    //删
    delete(client);
}

@SneakyThrows
void create(TransportClient client){
    for (int i = 0; i < 5; i++) {
        XContentBuilder builder = XContentFactory.jsonBuilder()
                .startObject()
                .field("empName", "name" + i)
                .field("age", new Random().nextInt(100))
                .field("createTime", new Date())
                .endObject();
        IndexResponse response = client.prepareIndex("emp", "_doc", String.valueOf(i))
                .setSource(builder)
                .get();
//                //还可以不指定id
//                IndexResponse response = client.prepareIndex("emp", "_doc")
//                        .setSource(builder)
//                        .get();
        System.out.println(response.getResult());
    }
}这里我用prepareIndex指定id和不指定id分别执行了一遍，所以应该有10条文档产生。
通过Kibana控制台验证一下执行结果：


结果是执行成功的！
正好，用查询API来验证一下。
GET API 查询单个、所有文档相关API

代码生成的时候，又生成id为0~4的文档，就查一下id为3的吧先：
<pre class="prettyprint hljs typescript" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, "Courier New", monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">private void get(TransportClient client) {
    GetResponse response = client.prepareGet("emp", "_doc", "3").get();
    String index = response.getIndex();//获取索引名称
    String type = response.getType();//获取索引类型
    String id = response.getId();//获取索引id
    System.out.println("index:" + index);
    System.out.println("type:" + type);
    System.out.println("id:" + id);
    System.out.println(response.getSourceAsString());
}

执行成功！
查询所有的API试一下：
<pre class="prettyprint hljs vbscript" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, "Courier New", monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">private void getAll(TransportClient client) {
    SearchResponse response = client.prepareSearch("emp").get();
    SearchHits searchHits = response.getHits();
    SearchHit[] hits = searchHits.getHits();
    for (SearchHit hit : hits) {
        String res = hit.getSourceAsString();
        System.out.println("res" + res);
    }
}

OK，成功查询出所有文档。
这里可以对比Kibana Dev Tools控制台返回的json结果，
<pre class="prettyprint hljs xquery" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, "Courier New", monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">{
  "took" : 134,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 10,
      "relation" : "eq"
    },
    "max_score" : 1.0,
    "hits" : [
      {
        "_index" : "emp",
        "_type" : "_doc",
        "_id" : "ze2qFnQBZf6fz3EOVZFP",
        "_score" : 1.0,
        "_source" : {
          "empName" : "name0",
          "age" : 35,
          "createTime" : "2020-08-22T14:54:54.999Z"
        }
      },
      // 中间的结果略...
      {
        "_index" : "emp",
        "_type" : "_doc",
        "_id" : "4",
        "_score" : 1.0,
        "_source" : {
          "empName" : "name4",
          "age" : 56,
          "createTime" : "2020-08-22T15:05:58.480Z"
        }
      }
    ]
  }
}

Java API的一些方法名和ES查询结果JSON先关字段一般能对的上，如果平时控制台操作比较熟悉的话，再来使用API其实很简单了！
Update API

修改id为3的记录，将其name改为鲁班7号：
<pre class="prettyprint hljs cs" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, "Courier New", monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">private void update(TransportClient client) {
    try {
        UpdateResponse response = client.prepareUpdate("emp", "_doc", "3")
                .setDoc(XContentFactory.jsonBuilder()
                        .startObject()
                        .field("name", "鲁班7号")
                        .endObject())
                .get();
        System.out.println(response.getResult());
    } catch (IOException e) {
        e.printStackTrace();
    }
}验证一下：


Delete API

删除id为3的文档记录：
<pre class="prettyprint hljs cs" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, "Courier New", monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">private void delete(TransportClient client) {
    DeleteResponse response = client.prepareDelete("emp", "_doc", "3").get();
    System.out.println(response.getResult());
}
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