6、使用Java Low Level REST Client操作elasticsearch

1、 查看Index

创建Index时method使用PUT，查看Index时method使用GET

/**
 * 查看api信息
 *
 * @throws Exception
 */
public static void lookIndex(RestClient client) {
 String method = "GET";
 Stringendpoint = "/book";
 try {
 Request request = new Request(method, endpoint);
 Response response= client.performRequest(request);
 System.out.println(EntityUtils.toString(response.getEntity()));
 }catch (Exception e) {
 e.printStackTrace();
 }
}

运行后结果如下：

{
 "book": {
 "aliases": { }, 
 "mappings": { }, 
 "settings": {
 "index": {
 "creation_date": "1561263334053", 
 "number_of_shards": "5", 
 "number_of_replicas": "1", 
 "uuid": "mEeGPmbRR2Cc3Rg6mK4YCA", 
 "version": {
 "created": "5061399"
 }, 
 "provided_name": "book"
 }
 }
 }
}

2、 添加文档

构造一个Model对象

package es;
import java.util.Date;
public class ItBook {
 private String name;
 private String writer;
 private int count;
 private Date publishDate;
 // 省略 get set
}

创建基于该模型的Document

public static void addDocument(RestClient client) {
 try{
 String method = "PUT";
 String endpoint = "/book/it/1"; // 索引：图书【DB】 类型：小说【table】 文档：【表里的数据】
 ItBook book = new ItBook();
 book.setName("三国演义");
 book.setWriter("张飞");
 book.setCount(10);
 book.setPublishDate(new Date());
 String jsonStr = JSON.toJSONString(book);
 // JSON格式字符串
 HttpEntity entity = new NStringEntity(jsonStr, ContentType.APPLICATION_JSON);
 Request request = new Request(method, endpoint);
 request.setEntity(entity);
 Response response = client.performRequest(request);
 System.out.println(EntityUtils.toString(response.getEntity()));
 System.out.println("新增文档结束！！！");
 }catch (Exception e) {
 e.printStackTrace();
 }
}

测试返回结果

{
 "_index": "book", 
 "_type": "it", 
 "_id": "1", 
 "_version": 1, 
 "result": "created", 
 "_shards": {
 "total": 2, 
 "successful": 1, 
 "failed": 0
 }, 
 "created": true
}

3、 查询文档

根据ID查询文档

public static void queryDocument(RestClient client) {
 try{
 String method = "GET";
 String endpoint = "/book/it/1";
 Request request = new Request(method, endpoint);
 Response response = client.performRequest(request);
 System.out.println(EntityUtils.toString(response.getEntity()));
 System.out.println("查询文档结束！！！");
 }catch (Exception e) {
 e.printStackTrace();
 }
}

测试结果

{
 "_index": "book", 
 "_type": "it", 
 "_id": "1", 
 "_version": 1, 
 "found": true, 
 "_source": {
 "count": 10, 
 "name": "三国演义", 
 "publishDate": 1561471991012, 
 "writer": "张飞"
 }
}

返回的json字符串可以使用json类库转换成对象，例如使用fastjson。

查询所有it的文档

public static void queryAll(RestClient client) {
 try{
 String method = "POST";
 String endpoint = "/book/it/_search";
 HttpEntity entity = new NStringEntity("{\n" +
 " \"query\": {\n" +
 " \"match_all\": {}\n" +
 " }\n" +
 "}", ContentType.APPLICATION_JSON);
 Request request = new Request(method, endpoint);
 request.setEntity(entity);
 Response response = client.performRequest(request);
 System.out.println(EntityUtils.toString(response.getEntity()));
 System.out.println("查询所有数据:queryAll ！！！");
 }catch (Exception e) {
 e.printStackTrace();
 }
}

测试结果：

{
 "took": 441, 
 "timed_out": false, 
 "_shards": {
 "total": 5, 
 "successful": 5, 
 "skipped": 0, 
 "failed": 0
 }, 
 "hits": {
 "total": 1, 
 "max_score": 1, 
 "hits": [
 {
 "_index": "book", 
 "_type": "it", 
 "_id": "1", 
 "_score": 1, 
 "_source": {
 "count": 10, 
 "name": "三国演义", 
 "publishDate": 1561471991012, 
 "writer": "张飞"
 }
 }
 ]
 }
}