springboot整合Elasticsearch（数据检索）实现数据增删改查

一.初识Elasticsearch（简称es）

1.什么是es
是开源高可扩展的分布式的全文检索引擎,可以近乎实时存储和检索数据

特性：

• 近乎实时存储检索数据
• 扩展性好,可以扩展到上百台服务台
• 处理PB级数据 使用Java开发,核心使用Lucene
• 使用Restful的API隐藏Lucene的复杂性,使得全文检索变得简单

2.es的原理
根据内容进行分词,然后建立反向(倒排)索引,根据倒排索引进行搜索,速度快.

3.和mysql数据库相比

关系型数据库(mysql)	非关系型数据库ES
数据库Database	索引Index
表table	类型type
数据列column	字段field
约束schema	映射mapping

二.es的使用（Windows版本使用）

1.去官网Elasticsearch压缩包，解压缩包，进入bin,双击elasticsearch.bat运行.。
修改config/elasticsearch.yml,增加2句话

http.cors.enabled: true
http.cors.allow-origin: "*"

2.在springboot项目pom文件中引入maven依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-elasticsearch</artifactId>
</dependency>

3.在接口数据到层中继承接口 ElasticsearchRepository，自动关系映射

4.controller控制层，dao层继承ElasticsearchRepository接口后，可直接调用其自带的一些数据访问方法，实现增删改查。

import com.tjetc.dao.EmployeeDao;
import com.tjetc.domain.Employee;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.MultipartFile;

import java.io.File;
import java.io.IOException;
import java.util.List;
import java.util.Optional;

@Controller
@RequestMapping("/employee")
public class EmployeeController {
    @Autowired
    private EmployeeDao employeeDao;
    @GetMapping("/add")
    public String add(){
        return "add";
    }
    @PostMapping("/add")
    public String add(Employee employee, MultipartFile photo){

        if (photo!=null && photo.getSize()>0){
            File file = new File("C:/upload/");
            if (!file.exists()){
                file.mkdir();
            }
            String filename = photo.getOriginalFilename();
            File file1 = new File(file, filename);
            try {
                photo.transferTo(file1);
                employee.setPhotopath("upload/"+filename);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        employeeDao.save(employee);
        System.out.println("添加成功");
        return "redirect:/employee/list";
    }
    @RequestMapping("/list")
    private String listByName(@RequestParam(defaultValue = "")String name,
                              @RequestParam(defaultValue = "0")Integer pageNum,
                              @RequestParam(defaultValue = "3")Integer pageSize, Model model){
        Pageable pageable= PageRequest.of(pageNum,pageSize);

        List<Employee> list1 = employeeDao.findByName(name, pageable);
        System.out.println("list哈哈哈啊:"+list1);

        Page<Employee> page = employeeDao.findAll(pageable);
        List<Employee> list = page.getContent();
        System.out.println("page的个数："+page.getTotalPages());
        System.out.println("getNumber："+page.getNumber());
        System.out.println("getSize："+page.getSize());
        System.out.println("getNumberOfElements："+page.getNumberOfElements());
        Iterable<Employee> all = employeeDao.findAll();
        /*List<Employee> list = (List)employeeDao.findAll();*/
        for (Employee employee : list) {
            System.out.println("employee = " + employee);
        }
        /* List<Product> list = productDao.findByProduct(name, pageable);
        System.out.println("list的值："+list);*/
        System.out.println("page = " + page);
        model.addAttribute("list",list);
        model.addAttribute("page",page);
        model.addAttribute("name",name);
        return "list";
    }
    @RequestMapping("/findById")
    public String findById(Integer id,Model model){
        Employee employee = employeeDao.findById(id).get();
        System.out.println("employee = " + employee);
        model.addAttribute("e",employee);
        return "update";
    }

    @PostMapping("/update")
    public String update(Employee employee, MultipartFile photo){
        if (photo!=null && photo.getSize()>0){
            File file = new File("C:/upload/");
            if (!file.exists()){
                file.mkdir();
            }
            String filename = photo.getOriginalFilename();
            File file1 = new File(file, filename);
            try {
                photo.transferTo(file1);
                employee.setPhotopath("upload/"+filename);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        employeeDao.save(employee);
        System.out.println("修改成功");
        return "redirect:/employee/list";
    }
    @RequestMapping("/del")
    public String del(Integer id){
        employeeDao.deleteById(id);
        System.out.println("删除成功");
        return "redirect:/employee/list";
    }

}

5.dao数据层

import com.tjetc.domain.Employee;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.elasticsearch.repository.ElasticsearchRepository;

import java.util.List;

public interface EmployeeDao extends ElasticsearchRepository<Employee,Integer> {
    Page<Employee> findAll(Pageable pageable);
    List<Employee> findByName(String name, Pageable pageable);
}

6.domain实体类对象属性定义格式

import org.springframework.data.annotation.Id;
import org.springframework.data.elasticsearch.annotations.Document;
import org.springframework.data.elasticsearch.annotations.Field;
import org.springframework.data.elasticsearch.annotations.FieldType;

@Document(indexName = "employee")
public class Employee {
    @Id
    @Field(type = FieldType.Integer,store = true,index = false)
    private Integer id;
    @Field(type = FieldType.Text,store = true,index = true,analyzer = "ik_max_word")
    private String name;
    @Field(type = FieldType.Text,store = true,index = true,analyzer = "ik_max_word")
    private Double price;
    @Field(type = FieldType.Text,store = true,index = true,analyzer = "ik_max_word")
    private String photopath;

    public Employee(Integer id, String name, Double price, String photopath) {
        this.id = id;
        this.name = name;
        this.price = price;
        this.photopath = photopath;
    }

    public Employee() {
    }