Elasticsearch运用于实际的SpringBoot项目

一、SpringBoot整合Elasticsearch

1.spring boot 引入对应的依赖包

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-data-elasticsearch</artifactId>
	<version>2.2.2.RELEASE</version>
</dependency>

注意：这里的依赖包版本必须与es服务版本对应，比如，上述依赖包2.2.2.RELEASE就对应着elasticsearch-6.4.3。

2.在yml文件中配置相应的es服务信息

spring:
  data:
    elasticsearch:
      cluster-name: es6
      cluster-nodes: 192.168.1.9:9300

3.常见错误解决
（1）如果出现如下错误

java.lang.IllegalStateException: availableProcessors is already set to [4], rejecting [4]

解决：

@Configuration
public class ESConfig {

    /**
     * 解决由netty引起的问题
     */
    @PostConstruct
    void init() {
        System.setProperty("es.set.netty.runtime.available.processors", "false");
    }
}

二、Elasticsearch在SpringBoot中的应用

不建议通过ElasticsearchTemplate 在spring boot中对索引进行直接管理。有两个原因：第一，因为索引就相当于数据库表，在Java中我们是不会通过代码频繁的去建表、删表的。同理es也是一样；第二，通过Java建索引不够灵活，很多类型(FieldType)不能通过Java设置，并且主分片与副本分片不能通过Java来设置。
1.关于索引的操作
（1）索引的创建与更新

第一步：创建文档类

package imooc.es.pojo;

import lombok.Getter;
import lombok.Setter;
import org.springframework.data.annotation.Id;
import org.springframework.data.elasticsearch.annotations.Document;
import org.springframework.data.elasticsearch.annotations.Field;

@Document(indexName = "stu",type = "_doc")
@Data
public class Stu {

    @Id
    private Long stuId;

    @Field(store = true)
    private String name;

    @Field(store = true)
    private Integer age;

    @Field(store = true)
    private Float money;

    @Field(store = true)
    private String sign;

    @Field(store = true)
    private String description;
}

第二步：创建索引或更新索引
如果该文档记录在索引中存在，即更新，不存在则新增

package com.test;

import imooc.Application;
import imooc.es.pojo.Stu;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.data.elasticsearch.core.ElasticsearchTemplate;
import org.springframework.data.elasticsearch.core.query.IndexQuery;
import org.springframework.data.elasticsearch.core.query.IndexQueryBuilder;
import org.springframework.test.context.junit4.SpringRunner;

@RunWith(SpringRunner.class)
@SpringBootTest(classes = Application.class)
public class ESTest {

    @Autowired
    private ElasticsearchTemplate esTemplate;

    @Test
    public void createIndexStu() {

        Stu stu = new Stu();
        stu.setStuId(1002L);
        stu.setName("spider man");
        stu.setAge(19);
        IndexQuery indexQuery = new IndexQueryBuilder().withObject(stu).build();
        esTemplate.index(indexQuery);
    }
}

（2）索引的删除

 	@Test
    public void deleteIndexStu() {

        esTemplate.deleteIndex(Stu.class);
    }

2.关于文档的操作
（1）文档更新

 	@Test
    public void updateStuDoc() {

        Map<String, Object> source = new HashMap<>();
        source.put("money",66.8F);
        source.put("sign","i am nononono");

        IndexRequest indexRequest = new IndexRequest();
        indexRequest.source(source);

        UpdateQuery updateQuery = new UpdateQueryBuilder()
                                        .withClass(Stu.class)
                                        .withId("1002")
                                        .withIndexRequest(indexRequest)
                                        .build();
        esTemplate.update(updateQuery);
    }

（2）文档查询

	@Test
    public void queryStuDoc() {

        GetQuery getQuery = new GetQuery();
        getQuery.setId("1002");
        Stu stu = esTemplate.queryForObject(getQuery, Stu.class);
        System.out.println(stu);
    }

（3）文档删除

 	@Test
    public void deleteStuDoc() {

        String delete = esTemplate.delete(Stu.class, "1002");
        System.out.println(delete);
    }

（4）文档分页搜索

	@Test
    public void searchStuDocForPage() {

        Pageable pageable = PageRequest.of(0, 10);
        NativeSearchQuery searchQuery = new NativeSearchQueryBuilder()
                .withQuery(QueryBuilders.matchQuery("description", "super man"))
                .withPageable(pageable)
                .build();
        AggregatedPage<Stu> stus = esTemplate.queryForPage(searchQuery, Stu.class);
        System.out.println(stus.getTotalPages());
        System.out.println(stus.getContent());
    }

（5）搜索内容高亮显示

 	@Test
    public void searchStuDocForHighLight() {

        String preTags = "<font color='red'>";
        String postTags = "</font>";
        Pageable pageable = PageRequest.of(0, 2);
        NativeSearchQuery searchQuery = new NativeSearchQueryBuilder()
                .withQuery(QueryBuilders.matchQuery("description", "man"))
                .withHighlightFields(new HighlightBuilder.Field("description").preTags(preTags).postTags(postTags))
                .withPageable(pageable)
                .build();
        AggregatedPage<Stu> stus = esTemplate.queryForPage(searchQuery, Stu.class, new SearchResultMapper() {
            @Override
            public <T> AggregatedPage<T> mapResults(SearchResponse searchResponse, Class<T> aClass, Pageable pageable) {

                SearchHits hits = searchResponse.getHits();
                List<Stu> stuList = new ArrayList<>();
                for (SearchHit searchHit : hits){
                    HighlightField highlightField = searchHit.getHighlightFields().get("description");
                    String description = highlightField.getFragments()[0].toString();
                    Object stuId = searchHit.getSourceAsMap().get("stuId");
searchHit.getSourceAsMap().get("name");
                    Integer age = (Integer) searchHit.getSourceAsMap().get("age");
                    Object money = searchHit.getSourceAsMap().get("money");
searchHit.getSourceAsMap().get("sign");
                    Stu stu = new Stu();
                    stu.setDescription(description);
                    stu.setStuId(Long.valueOf(stuId.toString()));
                    stu.setAge(age);
                    stu.setMoney(Float.valueOf(money.toString()));
                    stuList.add(stu);
                }
                if (stuList.size() > 0) {
                    return new AggregatedPageImpl<>((List<T>)stuList);
                }
                return null;
            }
        });
        System.out.println(stus.getTotalPages());
        System.out.println(stus.getContent());
    }

（6）搜索内容实现排序

@Test
    public void searchStuDocForSort() {

        String preTags = "<font color='red'>";
        String postTags = "</font>";
        Pageable pageable = PageRequest.of(0, 2);

        SortBuilder sortBuilder = new FieldSortBuilder("money");
        sortBuilder.order(SortOrder.ASC);
        NativeSearchQuery searchQuery = new NativeSearchQueryBuilder()
                .withQuery(QueryBuilders.matchQuery("description", "man"))
                .withHighlightFields(new HighlightBuilder.Field("description").preTags(preTags).postTags(postTags))
                .withSort(sortBuilder)
                .withPageable(pageable)
                .build();
        AggregatedPage<Stu> stus = esTemplate.queryForPage(searchQuery, Stu.class);
        System.out.println(stus.getTotalPages());
        System.out.println(stus.getContent());
    }