Elasticsearch的CRUD：API之增删改查
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()); }#java##程序员#
查看3道真题和解析
