近几篇ElasticSearch系列：

1、阿里云服务器Linux系统安装配置ElasticSearch搜索引擎

2、Linux系统中ElasticSearch搜索引擎安装配置Head插件

3、ElasticSearch搜索引擎安装配置中文分词器IK插件

4、ElasticSearch搜索引擎安装配置拼音插件pinyin

5、ElasticSearch搜索引擎在JavaWeb项目中的应用

一、前言

前四篇简单介绍了ElasticSearch（以下简称ES）在阿里云服务器Linux系统上的部署配置等。本篇将简述一下ES在JavaWeb项目中的应用。本项目前端框架是Vue.js，前后端数据交互采用是常用的SSM框架，项目管理工具为Maven，ES为6.3.2版本。

二、正文

1、ES在Maven中添加相应依赖，如下所示：

<dependency>
    <groupId>org.elasticsearch</groupId>
    <artifactId>elasticsearch</artifactId>
    <version>6.2.4</version>
</dependency>
<dependency>
    <groupId>org.elasticsearch.client</groupId>
    <artifactId>transport</artifactId>
    <version>6.2.4</version>
</dependency>

2、@Configuration注解新建的 “ElasticSearchConfig” 类，用来初始化ES客户端TransportClient连接，通过setting来创建，若不指定则默认链接的集群名为elasticsearch，如下图所示：

@Configuration
public class ElasticSearchConfig {

    @Bean
    public TransportClient client() throws UnknownHostException {
        Settings settings = Settings.builder().build();
        TransportClient client = new PreBuiltTransportClient(settings)
                .addTransportAddress(new TransportAddress(InetAddress.getByName("部署ES的IP地址"), 9300));
        return client;
    }
}

3、jsp里首先需要导入jquery与Vue，然后css样式仅供参考，如下图所示：

<div id="search_main" style="position: relative;top: -360px;left: -200px;width: 100%;height: 50px;text-align: center">
    <input id="search_input1" type="text" name="search1" placeholder="请输入企业名称。如“阿里巴巴”或“alibaba”"
           style="height: 50px;width: 720px;border: none;font-size: 18px;" onkeypress="EnterPress(event)" onkeydown="EnterPress()"
           v-model="searchText" v-on:keyup="showName(searchText)"/>
    <img id="voice" src="icon/voice1.png" width="35" height="35" style="position: absolute;left: 1145px;top: 7px;"/>
    <button id="search_button1" type="button" style="position: relative;left: -4px;top: 1px;height: 50px;width: 100px;border: none;background-color: #1db5ee">
        <font size="4" color="white" style="align-content: center">搜索</font>
    </button>
    <font id="searchType" style="display: none">企业名</font>
    <div id="parentRelationSearch" v-for="(company, cIndex) in companyList" style="position: relative;top: 0px;left: 474px;height: auto;width: 719px;background-color: #ffffff;z-index: 99">
        <div class="relationSearch" v-on:click="putVal(company.name)" v-on:mouseenter="mouseEnter($event)" v-on:mouseleave="mouseLeave($event)" style="position: relative;top: 0px;left: 0px;width: 100%;height: 35px;border-bottom: 1px solid #e8e8e8;line-height: 35px;">
            <font size="2" style="position: absolute;left: 5px">{{company.name}}</font>
            <font size="1.5" style="position: absolute;left: 92%;">{{company.score}}</font>
        </div>
    </div>
</div>

4、id为search_main的元素为Vue实例挂载的元素节点，以及showName函数（ajax请求）为keyup事件，putVal函数（将用户选中的元素值赋值给搜索框）为click事件，mouseEnter、mouseLeave函数分别为mouseenter、mouseleave事件，如下图所示：

var vm1 = new Vue({
    el: '#search_main',
    data: {
        searchText: "",
        companyList: [],
    },
    mounted: function () {
        this.showName();
        this.putVal();
        this.mouseEnter();
        this.mouseLeave();
    },
    methods: {
        putVal: function (val) {
            $("#search_input1").val(val);
            $(".relationSearch").hide();
            document.getElementById("search_input1").focus();
        },
        showName: function (key) {
            console.log(key);
            if (key.length != 0) {
                var searchType = document.getElementById("searchType").innerText;
                if (searchType == "全部" || searchType == "企业名") {
                    $(".relationSearch").show();
                    var _this = this;
                    this.$http.get("http://localhost:8080/auto_think.do?key=" + key).then(function (jsonResult) {
                        _this.companyList = (jsonResult.body);
                    });
                }
            } else {
                $(".relationSearch").hide();
            }
        },
        mouseEnter: function ($event) {
            $event.currentTarget.className = "relationSearch searchActive";
        },
        mouseLeave: function ($event) {
            $event.currentTarget.className = "relationSearch";
        }
    }
});

上述mouseEnter函数是用于动态添加class，用以实现鼠标移入则修改元素的背景功能：

.searchActive{
     background-color:#e8e8e8;
}

5、QueryBuilder是ES提供的一个查询接口，进行单个匹配值为key的文档。SearchRequestBuilder根据索引与类型构造查询请求，设置查询条件和分页参数，再获取返回值并进行处理，最后返回，如下图所示：

package controller;

import entity.ElasticSearchResult;
import org.elasticsearch.action.index.IndexResponse;
import org.elasticsearch.action.search.SearchRequestBuilder;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.client.transport.TransportClient;
import org.elasticsearch.common.xcontent.XContentBuilder;
import org.elasticsearch.common.xcontent.XContentFactory;
import org.elasticsearch.index.query.QueryBuilder;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.search.SearchHit;
import org.elasticsearch.search.SearchHits;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

import java.io.IOException;
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.List;

@Controller
public class ElasticSearchController {

    @Autowired
    private TransportClient client;

    //搜索自动联想
    @GetMapping("/auto_think.do")
    @ResponseBody
    public List<ElasticSearchResult> findIndexRecordByName(@RequestParam(name = "key") String key) {
        // 构造查询请求
        QueryBuilder bq = QueryBuilders.matchQuery("name.pinyin", key);
        SearchRequestBuilder searchRequest = client.prepareSearch("medcl").setTypes("folks");

        // 设置查询条件和分页参数
        int start = 0;
        int size = 5;
        searchRequest.setQuery(bq).setFrom(start).setSize(size);

        // 获取返回值，并进行处理
        SearchResponse response = searchRequest.execute().actionGet();
        SearchHits shs = response.getHits();
        List<ElasticSearchResult> esResultList = new ArrayList<>();
        for (SearchHit hit : shs) {
            ElasticSearchResult esResult = new ElasticSearchResult();
            double score = hit.getScore();
            BigDecimal b = new BigDecimal(score);
            score = b.setScale(3, BigDecimal.ROUND_HALF_UP).doubleValue();
            String name = (String) hit.getSourceAsMap().get("name");
            System.out.println("score:" + score + "name:" + name);
            esResult.setScore(score);
            esResult.setName(name);
            esResultList.add(esResult);
        }
        return esResultList;
    }

    //向搜索引擎添加数据库所有企业
    public void addCorpName(String name) {
        try {
            XContentBuilder content = XContentFactory.jsonBuilder()
                    .startObject()
                    .field("name", name)
                    .endObject();

            IndexResponse result = client.prepareIndex("medcl", "folks")
                    .setSource(content)
                    .get();
            System.out.println(result.getId());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

下述为ElasticSearchResult实体类：

package entity;

public class ElasticSearchResult {

    private double score;

    private String name;

    public double getScore() {
        return score;
    }

    public void setScore(double score) {
        this.score = score;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

再附上向指定索引与类型添加、删除文档函数代码，如下所示：

public void add(String name) {
    try {
        XContentBuilder content = XContentFactory.jsonBuilder()
                .startObject()
                .field("name", name)
                .endObject();

        IndexResponse result = this.client.prepareIndex("medcl", "folks")
                .setSource(content)
                .get();
        System.out.println(result.getId());
    } catch (IOException e) {
        e.printStackTrace();
    }
}
public void deleteByName(String name){
    BulkRequestBuilder bulkRequest = client.prepareBulk();
    SearchResponse response = client.prepareSearch("medcl").setTypes("folks")
            .setSearchType(SearchType.DFS_QUERY_THEN_FETCH)
            .setQuery(QueryBuilders.termQuery("name", name))
            .setFrom(0).setSize(20).setExplain(true).execute().actionGet();
    for(SearchHit hit : response.getHits()){
        String id = hit.getId();
        bulkRequest.add(client.prepareDelete("medcl", "folks", id).request());
    }
    BulkResponse bulkResponse = bulkRequest.get();

    if (bulkResponse.hasFailures()) {
        for(BulkItemResponse item : bulkResponse.getItems()){
            System.out.println(item.getFailureMessage());
        }
    }else {
        System.out.println("delete ok");
    }
}

最后附上功能效果图，如下图所示：

至此是对ElasticSearch搜索引擎在JavaWeb项目中的应用的一个简单介绍。

如有疏漏错误之处，还请不吝赐教！