jsp 语言 JSP 与 Elasticsearch 进行全文检索示例

JSP阿木 发布于 14 天前 4 次阅读

JSP 与 Elasticsearch 进行全文检索示例

随着互联网的快速发展，信息量的爆炸式增长，如何快速、准确地检索到所需信息成为了一个重要课题。全文检索技术应运而生，它能够对大量文本数据进行高效检索。Elasticsearch 是一个基于 Lucene 的开源全文搜索引擎，具有高性能、易扩展等特点。本文将结合 JSP（JavaServer Pages）技术，展示如何使用 Elasticsearch 实现一个简单的全文检索示例。

环境准备

在开始编写代码之前，我们需要准备以下环境：

1. JDK 1.8 或更高版本

2. Tomcat 8.5 或更高版本

3. Elasticsearch 6.x 或更高版本

4. Maven 3.6 或更高版本

项目结构

以下是项目的目录结构：


src

|-- main

|   |-- java

|   |   |-- com

|   |   |   |-- example

|   |   |   |   |-- ElasticsearchUtil.java

|   |   |   |   |-- SearchServlet.java

|   |-- webapp

|       |-- WEB-INF

|       |   |-- web.xml

|       |-- index.jsp

1. ElasticsearchUtil 类

ElasticsearchUtil 类负责连接 Elasticsearch 集群，并提供基本的搜索功能。

java
package com.example;



import org.elasticsearch.client.RestHighLevelClient;

import org.elasticsearch.client.RequestOptions;

import org.elasticsearch.client.RestClient;

import org.elasticsearch.client.RestClientBuilder;

import org.elasticsearch.client.core.CountRequest;

import org.elasticsearch.client.core.CountResponse;

import org.elasticsearch.index.query.QueryBuilders;

import org.elasticsearch.search.builder.SearchSourceBuilder;

import org.elasticsearch.search.fetch.subphase.FetchSourceContext;

import org.elasticsearch.search.fetch.subphase.highlight.HighlightBuilder;

import org.elasticsearch.search.fetch.subphase.highlight.HighlightField;



import java.io.IOException;

import java.util.HashMap;

import java.util.Map;



public class ElasticsearchUtil {

    private static final String HOST = "localhost";

    private static final int PORT = 9200;

    private static final String SCHEME = "http";

    private static final String INDEX_NAME = "test_index";

    private static final RestHighLevelClient client = new RestHighLevelClient(

            RestClient.builder(

                    new HttpHost(HOST, PORT, SCHEME)

            )

    );



public static void closeClient() throws IOException {

        client.close();

    }



public static Map<String, Object> search(String query) throws IOException {

        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();

        searchSourceBuilder.query(QueryBuilders.matchQuery("content", query));

        searchSourceBuilder.fetchSource(new FetchSourceContext(true, new String[]{"title", "content"}, null));

        searchSourceBuilder.highlighter(new HighlightBuilder().field("content").preTags("<em>").postTags("</em>"));



CountRequest countRequest = new CountRequest(INDEX_NAME);

        countRequest.query(QueryBuilders.matchQuery("content", query));

        CountResponse countResponse = client.count(countRequest, RequestOptions.DEFAULT);

        int count = countResponse.getCount();



SearchResponse searchResponse = client.search(searchSourceBuilder.request(), RequestOptions.DEFAULT);

        Map<String, Object> result = new HashMap<>();

        result.put("count", count);

        result.put("hits", searchResponse.getHits().getHits());



return result;

    }

}

2. SearchServlet 类

SearchServlet 类负责处理 JSP 页面的搜索请求，并返回搜索结果。

java
package com.example;



import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

import java.util.Map;



@WebServlet("/search")

public class SearchServlet extends HttpServlet {

    @Override

    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        String query = req.getParameter("query");

        Map<String, Object> result = ElasticsearchUtil.search(query);

        req.setAttribute("result", result);

        req.getRequestDispatcher("/index.jsp").forward(req, resp);

    }

}

3. web.xml 配置

在 `web.xml` 文件中，我们需要配置 SearchServlet。

xml
<web-app>

    <servlet>

        <servlet-name>SearchServlet</servlet-name>

        <servlet-class>com.example.SearchServlet</servlet-class>

    </servlet>

    <servlet-mapping>

        <servlet-name>SearchServlet</servlet-name>

        <url-pattern>/search</url-pattern>

    </servlet-mapping>

</web-app>

4. index.jsp 页面

index.jsp 页面用于展示搜索结果。

jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>

<html>

<head>

    <title>全文检索示例</title>

</head>

<body>

    <form action="search" method="get">

        <input type="text" name="query" placeholder="请输入搜索内容">

        <input type="submit" value="搜索">

    </form>

    <h1>搜索结果（共 ${result.count} 条）：</h1>

    <ul>

        <%

            for (SearchHit hit : (List<SearchHit>) result.get("hits")) {

                String title = hit.getSource().get("title").toString();

                String content = hit.getSource().get("content").toString();

                String highlightedContent = hit.getHighlightFields().get("content").get(0).getFragments()[0].toString();

        %>

        <li>

            <h2><a href="${title}">${title}</a></h2>

            <p>${highlightedContent}</p>

        </li>

        <%

            }

        %>

    </ul>

</body>

</html>

总结

本文通过 JSP 和 Elasticsearch 实现了一个简单的全文检索示例。在实际应用中，可以根据需求对代码进行扩展和优化，例如添加分页、排序、过滤等功能。希望本文能对您有所帮助。