使用Springboot整合Elasticsearch

全文搜索引擎

全文搜索引擎是目前广泛应用的主流搜索引擎，也称为全文检索。它的工作原理是计算机索引程序通过扫描文章中的每一个词，对每一个词建立一个索引，指明该词在文章中出现的次数和位置，当用户查询时，检索程序就根据事先建立的索引进行查找，并将查找的结果反馈给用户的检索方式。这个过程类似于通过字典中的检索字表查字的过程。

Springboot整合Elasticsearch:

步骤：

1. 创建一个SpringBoot工程，选择以下模块：Lombok、Web、Spring Data Elasticsearch

2. 编辑application.yml文件

spring:
  elasticsearch:
    uris: http://localhost:9200

3.基本操作

使用Spring Data Elasticsearch提供的工具类：ElasticsearchRestTemplate

常用注解：

• @Document 标记实体类为文档对象

• @Id 标记为文档id

• @Field 标记为文档字段

@Data
@AllArgsConstructor
@NoArgsConstructor
@Document(indexName = "student") //标记实体类为文档对象，并指定索引名称
public class Student implements Serializable {
    @Id
    @Field(type = FieldType.Keyword) //标记为文档id，不分词
    private Integer id;
    @Field(type = FieldType.Text) // 标记为文档字段，分词
    private String name;
    @Field(type = FieldType.Integer)  //标记为文档字段，不分词
    private Integer age;
    @Field(type = FieldType.Text)
    private String sex;
    @Field(type = FieldType.Text)
    private String school;
}

编写创建索引Controller:

@RestController
@RequiredArgsConstructor
@RequestMapping("index")
public class IndexController {

    private final ElasticsearchRestTemplate restTemplate;

    /**
     * 创建索引
     */
    @GetMapping("/create")
    public String create(){
        IndexOperations indexOperations = restTemplate.indexOps(Student.class);
        indexOperations.create();
        return "OK!";
    }
}

编写存入，并且获取文档Controller

@RestController
@RequiredArgsConstructor
@RequestMapping("doc")
public class DocController {

    private final ElasticsearchRestTemplate restTemplate;

    @GetMapping("/create")
    public String create(){
        restTemplate.save(new Student(1,"zhangsan",18,"男","Beijing"));
        return "success……";
    }

    @GetMapping("/batch")
    public String batch(){
        ArrayList<Student> list = new ArrayList<>();
        list.add(new Student(2,"Lisi",19,"男","北京大学"));
        list.add(new Student(3,"Wanger",29,"男","清华大学"));
        list.add(new Student(4,"Mazi",39,"男","本稻田大学"));
        list.add(new Student(5,"Waibozi",15,"女","东京大学"));
        list.add(new Student(6,"Yuzhanao",18,"男","北京大学"));
        restTemplate.save(list);
        return "batch====>success……";
    }

    @RequestMapping("/{id}")
    public Student findById(@PathVariable Integer id){
        Student student = restTemplate.get(id.toString(),Student.class);
        return student;
    }

    @RequestMapping("/all")
    public List<Student> findAll(){
        SearchHits<Student> hits = restTemplate.search(Query.findAll(),Student.class);
        System.out.println(hits.getTotalHits()); //总个数

        List<Student> list = hits.stream()
                .map(hit -> hit.getContent())
                .collect(Collectors.toList());
        return list;
    }
}