Elasticsearch编程

要将搜索的功能与前端对接，我们必须要使用Java代码来实现对Elasticsearch的操作。我们要使用一个JobService类来实现之前我们用RESTFul完成的操作

一、环境准备

1、准备IDEA项目结构

创建elasticsearch_example项目
创建包结构如下所示

包	说明
cn.it.elasticsearch.entity	存放实体类
cn.it.elasticsearch.service	存放服务接口
cn.it.elasticsearch.service.impl	存放服务接口实现类

2、准备POM依赖

<repositories><!-- 代码库 -->
    <repository>
        <id>aliyun</id>
        <url>http://maven.aliyun.com/nexus/content/groups/public/</url>
        <releases>
            <enabled>true</enabled>
        </releases>
        <snapshots>
            <enabled>false</enabled>
            <updatePolicy>never</updatePolicy>
        </snapshots>
    </repository>
</repositories>

<dependencies>
    <dependency>
        <groupId>org.elasticsearch.client</groupId>
        <artifactId>elasticsearch-rest-high-level-client</artifactId>
        <version>7.6.1</version>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-core</artifactId>
        <version>2.11.1</version>
    </dependency>
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>fastjson</artifactId>
        <version>1.2.62</version>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.testng</groupId>
        <artifactId>testng</artifactId>
        <version>6.14.3</version>
        <scope>test</scope>
    </dependency>
</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.1</version>
            <configuration>
                <target>1.8</target>
                <source>1.8</source>
            </configuration>
        </plugin>
    </plugins>
</build>

3、???????创建用于保存职位信息的实体类

注意：

在id字段上添加一个?@JSONField注解，并配置注解的serialize为false，表示该字段无需转换为JSON，因为它就是文档的唯一ID。

?参考代码：

public class JobDetail {

    // 因为此处无需将id序列化为文档中
    @JSONField(serialize = false)
    private long id;            // 唯一标识
    private String area;        // 职位所在区域
    private String exp;         // 岗位要求的工作经验
    private String edu;         // 学历要求
    private String salary;      // 薪资范围
    private String job_type;    // 职位类型（全职/兼职）
    private String cmp;         // 公司名
    private String pv;          // 浏览量
    private String title;       // 岗位名称
    private String jd;          // 职位描述

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public String getArea() {
        return area;
    }

    public void setArea(String area) {
        this.area = area;
    }

    public String getExp() {
        return exp;
    }

    public void setExp(String exp) {
        this.exp = exp;
    }

    public String getEdu() {
        return edu;
    }

    public void setEdu(String edu) {
        this.edu = edu;
    }

    public String getSalary() {
        return salary;
    }

    public void setSalary(String salary) {
        this.salary = salary;
    }

    public String getJob_type() {
        return job_type;
    }

    public void setJob_type(String job_type) {
        this.job_type = job_type;
    }

    public String getCmp() {
        return cmp;
    }

    public void setCmp(String cmp) {
        this.cmp = cmp;
    }

    public String getPv() {
        return pv;
    }

    public void setPv(String pv) {
        this.pv = pv;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getJd() {
        return jd;
    }

    public void setJd(String jd) {
        this.jd = jd;
    }

    @Override
    public String toString() {
        return "JobDetail{" +
                "id=" + id +
                ", area='" + area + '\'' +
                ", exp='" + exp + '\'' +
                ", edu='" + edu + '\'' +
                ", salary='" + salary + '\'' +
                ", job_type='" + job_type + '\'' +
                ", cmp='" + cmp + '\'' +
                ", pv='" + pv + '\'' +
                ", title='" + title + '\'' +
                ", jd='" + jd + '\'' +
                '}';
    }
}

4、???????编写接口和实现类

cn.it.elasticsearch.service包中创建JobFullTextService接口，该接口中定义了职位全文检索相关的Java?API接口。

参考代码：

/**
 * 定义JobFullTextService
 */
public interface JobFullTextService {
    // 添加一个职位数据
    void add(JobDetail jobDetail);

    // 根据ID检索指定职位数据
    JobDetail findById(long id) throws IOException;

    // 修改职位薪资
    void update(JobDetail jobDetail) throws IOException;

    // 根据ID删除指定位置数据
    void deleteById(long id) throws IOException;

    // 根据关键字检索数据
    List<JobDetail> searchByKeywords(String keywords) throws IOException;

    // 分页检索
    Map<String, Object> searchByPage(String keywords, int pageNum, int pageSize) throws IOException;

    // scroll分页解决深分页问题
    Map<String, Object> searchByScrollPage(String keywords, String scrollId, int pageSize) throws IOException;

    // 关闭ES连接
    void close() throws IOException;
;
}

?5、???????创建实现类

在cn.it.elasticsearch.service.impl包下创建一个实现类：JobFullTextServiceImpl，并实现上面的接口。

参考代码：

public class JobFullTextServiceImpl implements JobFullTextService {
    @Override
    public void add(JobDetail jobDetail) {
        
    }

    @Override
    public void update(JobDetail jobDetail) {

    }

    @Override
    public JobDetail findById(long id) {
        return null;
    }

    @Override
    public boolean deleteById(long id) {
        return false;
    }

    @Override
    public List<JobDetail> searchByKeywords(String keywords) {
        return null;
    }

    @Override
    public Map<String, Object> searchByPage(String keywords, int pageNum, int pageSize) {
        return null;
    }

    @Override
    public Map<String, Object> searchByScrollPage(String keywords, String scrollId, int pageSize) {
        return null;
    }
}