项目-20-开发社区搜索功能

原创 于 2021-06-25 14:54:45 发布 · 426 阅读 · 0 ·
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#项目管理

该博客详细介绍了如何开发社区搜索功能，包括使用Elasticsearch服务存储和检索帖子，发布事件时异步提交帖子和评论，以及在前端展示搜索结果。主要涉及ElasticsearchService、DiscussPostController、CommentController、EventConsumer和SearchController的交互。

开发社区搜索功能

搜索服务：

  • 将帖子保存至Elasticsearch服务器。

  • 从Elasticsearch服务器删除帖子。

  • 从Elasticsearch服务器搜索帖子。

发布事件：

  • 发布帖子时，将帖子异步的提交到Elasticsearch服务器。

  • 增加评论时，将帖子异步的提交到Elasticsearch服务器。

  • 在消费组件中增加一个方法，消费帖子发布事件。

显示结果：

  • 在控制器中处理搜索请求，在HTML上显示搜索结果。

1.ElasticsearchService

import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.search.SearchHit;
import org.elasticsearch.search.SearchHits;
import org.elasticsearch.search.fetch.subphase.highlight.HighlightBuilder;
import org.elasticsearch.search.fetch.subphase.highlight.HighlightField;
import org.elasticsearch.search.sort.SortBuilders;
import org.elasticsearch.search.sort.SortOrder;
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.data.elasticsearch.core.ElasticsearchTemplate;
import org.springframework.data.elasticsearch.core.SearchResultMapper;
import org.springframework.data.elasticsearch.core.aggregation.AggregatedPage;
import org.springframework.data.elasticsearch.core.aggregation.impl.AggregatedPageImpl;
import org.springframework.data.elasticsearch.core.query.NativeSearchQueryBuilder;
import org.springframework.data.elasticsearch.core.query.SearchQuery;
import org.springframework.stereotype.Service;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

@Service
public class ElasticsearchService {

    @Autowired
    private DiscussPostRepository discussRepository;
    @Autowired
    private ElasticsearchTemplate elasticTemplate;
	
    // 向Elasticsearch存入帖子
    public void saveDiscussPost(DiscussPost post) {
        discussRepository.save(post);
    }
	// 删除Elasticsearch中的帖子
    public void deleteDiscussPost(int id) {
        discussRepository.deleteById(id);
    }
	// 查询方法, keyword：检索关键字  current：当前页 limit：每页显示多少
    public Page<DiscussPost> searchDiscussPost(String keyword, int current, int limit) {
        SearchQuery searchQuery = new NativeSearchQueryBuilder()
                .withQuery(QueryBuilders.multiMatchQuery(keyword, "title", "content"))
                .withSort(SortBuilders.fieldSort("type").order(SortOrder.DESC))
                .withSort(SortBuilders.fieldSort("score").order(SortOrder.DESC))
                .withSort(SortBuilders.fieldSort("createTime").order(SortOrder.DESC))
                .withPageable(PageRequest.of(current, limit))
                .withHighlightFields(
                        new HighlightBuilder.Field("title").preTags("<em>").postTags("</em>"),
                        new HighlightBuilder.Field("content").preTags("<em>").postTags("</em>")
                ).build();

        return elasticTemplate.queryForPage(searchQuery, DiscussPost.class, new SearchResultMapper() {
            @Override
            public <T> AggregatedPage<T> mapResults(SearchResponse response, Class<T> aClass, Pageable pageable) {
                SearchHits hits = response.getHits();
                if (hits.getTotalHits() <= 0) {
                    return null;
                }

                List<DiscussPost> list = new ArrayList<>();
                for (SearchHit hit : hits) {
                    DiscussPost post = new DiscussPost();

                    String id = hit.getSourceAsMap().get("id").toString();
                    post.setId(Integer.valueOf(id));
                    String userId = hit.getSourceAsMap().get("userId").toString();
                    post.setUserId(Integer.valueOf(userId));
                    String title = hit.getSourceAsMap().get("title").toString();
                    post.setTitle(title);
                    String content = hit.getSourceAsMap().get("content").toString();
                    post.setContent(content);
                    String status = hit.getSourceAsMap().get("status").toString();
                    post.setStatus(Integer.valueOf(status));
                    String createTime = hit.getSourceAsMap().get("createTime").toString();
                    post.setCreateTime(new Date(Long.valueOf(createTime)));
                    String commentCount = hit.getSourceAsMap().get("commentCount").toString();
                    post.setCommentCount(Integer.valueOf(commentCount));

                    // 处理高亮显示的结果
                    HighlightField titleField = hit.getHighlightFields().get("title");
                    if (titleField != null) {
                        post.setTitle(titleField.getFragments()[0].toString());
                    }

                    HighlightField contentField = hit.getHighlightFields().get("content");
                    if (contentField != null) {
                        post.setContent(contentField.getFragments()[0].toString());
                    }
                    list.add(post);
                }

                return new AggregatedPageImpl(list, pageable,
                        hits.getTotalHits(), response.getAggregations(), response.getScrollId(), hits.getMaxScore());
            }
        });
    }
}

2.DiscussPostController

帖子发布成功后，触发发帖时间，向Elasticsearch添加帖子

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import java.util.*;

@Controller
@RequestMapping("/discuss")
public class DiscussPostController implements CommunityConstant {

    @Autowired
    private DiscussPostService discussPostService;
    @Autowired
    private HostHolder hostHolder;
    @Autowired
    private UserService userService;
    @Autowired
    private CommentService commentService;
    @Autowired
    private LikeService likeService;
    @Autowired
    private EventProducer eventProducer;

    @RequestMapping(path = "/add", method = RequestMethod.POST)
    @ResponseBody
    public String addDiscussPost(String title, String content) {
        User user = hostHolder.getUser();
        if (user == null) {
            return CommunityUtil.getJSONString(403, "你还没有登录哦!");
        }

        DiscussPost post = new DiscussPost();
        post.setUserId(user.getId());
        post.setTitle(title);
        post.setContent(content);
        post.setCreateTime(new Date());
        discussPostService.addDiscussPost(post);

        // 触发发帖事件
        Event event = new Event()
                .setTopic(TOPIC_PUBLISH)
                .setUserId(user.getId())
                .setEntityType(ENTITY_TYPE_POST)
                .setEntityId(post.getId());
        eventProducer.fireEvent(event);

        // 报错的情况,将来统一处理.
        return CommunityUtil.getJSONString(0, "发布成功!");
    }
}

3.CommentController

在给帖子增加评论后，触发事件，存入Elasticsearch

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import java.util.Date;

@Controller
@RequestMapping("/comment")
public class CommentController implements CommunityConstant {

    @Autowired
    private CommentService commentService;
    @Autowired
    private HostHolder hostHolder;
    @Autowired
    private EventProducer eventProducer;
    @Autowired
    private DiscussPostService discussPostService;

    @RequestMapping(path = "/add/{discussPostId}", method = RequestMethod.POST)
    public String addComment(@PathVariable("discussPostId") int discussPostId, Comment comment) {
        comment.setUserId(hostHolder.getUser().getId());
        comment.setStatus(0);
        comment.setCreateTime(new Date());
        commentService.addComment(comment);

        // 触发评论事件
        Event event = new Event()
                .setTopic(TOPIC_COMMENT)
                .setUserId(hostHolder.getUser().getId())
                .setEntityType(comment.getEntityType())
                .setEntityId(comment.getEntityId())
                .setData("postId", discussPostId);
        if (comment.getEntityType() == ENTITY_TYPE_POST) {
            DiscussPost target = discussPostService.findDiscussPostById(comment.getEntityId());
            event.setEntityUserId(target.getUserId());
        } else if (comment.getEntityType() == ENTITY_TYPE_COMMENT) {
            Comment target = commentService.findCommentById(comment.getEntityId());
            event.setEntityUserId(target.getUserId());
        }
        eventProducer.fireEvent(event);

        if (comment.getEntityType() == ENTITY_TYPE_POST) {
            // 触发发帖事件
            event = new Event()
                    .setTopic(TOPIC_PUBLISH)
                    .setUserId(comment.getUserId())
                    .setEntityType(ENTITY_TYPE_POST)
                    .setEntityId(discussPostId);
            eventProducer.fireEvent(event);
        }
        return "redirect:/discuss/detail/" + discussPostId;
    }
}

4.EventConsumer

消费发帖事件

import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.kafka.annotation.KafkaListener;
import org.springframework.stereotype.Component;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

@Component
public class EventConsumer implements CommunityConstant {

    private static final Logger logger = LoggerFactory.getLogger(EventConsumer.class);
    @Autowired
    private MessageService messageService;
    @Autowired
    private DiscussPostService discussPostService;
    @Autowired
    private ElasticsearchService elasticsearchService;
  
    // 消费发帖事件
    @KafkaListener(topics = {TOPIC_PUBLISH})
    public void handlePublishMessage(ConsumerRecord record) {
        if (record == null || record.value() == null) {
            logger.error("消息的内容为空!");
            return;
        }

        Event event = JSONObject.parseObject(record.value().toString(), Event.class);
        if (event == null) {
            logger.error("消息格式错误!");
            return;
        }

        DiscussPost post = discussPostService.findDiscussPostById(event.getEntityId());
        elasticsearchService.saveDiscussPost(post);
    }
}

5.SearchController

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

@Controller
public class SearchController implements CommunityConstant {
    @Autowired
    private ElasticsearchService elasticsearchService;
    @Autowired
    private UserService userService;  // 展示帖子的作者
    @Autowired
    private LikeService likeService; // 展示帖子点赞的数量

    // search?keyword=xxx
    @RequestMapping(path = "/search", method = RequestMethod.GET)
    public String search(String keyword, Page page, Model model) {
        // 搜索帖子
        org.springframework.data.domain.Page<DiscussPost> searchResult =
                elasticsearchService.searchDiscussPost(keyword, page.getCurrent() - 1, page.getLimit());
        // 聚合数据
        List<Map<String, Object>> discussPosts = new ArrayList<>();
        if (searchResult != null) {
            for (DiscussPost post : searchResult) {
                Map<String, Object> map = new HashMap<>();
                // 帖子
                map.put("post", post);
                // 作者
                map.put("user", userService.findUserById(post.getUserId()));
                // 点赞数量
                map.put("likeCount", likeService.findEntityLikeCount(ENTITY_TYPE_POST, post.getId()));

                discussPosts.add(map);
            }
        }
        model.addAttribute("discussPosts", discussPosts);
        model.addAttribute("keyword", keyword);

        // 分页信息
        page.setPath("/search?keyword=" + keyword);
        page.setRows(searchResult == null ? 0 : (int) searchResult.getTotalElements());

        return "/site/search";
    }
}

6.search.html

<!-- 帖子列表 -->
				<ul class="list-unstyled mt-4">
					<li class="media pb-3 pt-3 mb-3 border-bottom" th:each="map:${discussPosts}">
						<img th:src="${map.user.headerUrl}" class="mr-4 rounded-circle" alt="用户头像" style="width:50px;height:50px;">
						<div class="media-body">
							<h6 class="mt-0 mb-3">
								<a th:href="@{|/discuss/detail/${map.post.id}|}" th:utext="${map.post.title}">标题</a>
							</h6>
							<div class="mb-3" th:utext="${map.post.content}">
								内容
							</div>
							<div class="text-muted font-size-12">
								<u class="mr-3" th:utext="${map.user.username}">作者</u>
								发布于 <b th:text="${#dates.format(map.post.createTime,'yyyy-MM-dd HH:mm:ss')}">时间</b>
								<ul class="d-inline float-right">
									<li class="d-inline ml-2">赞 <i th:text="${map.likeCount}">11</i></li>
									<li class="d-inline ml-2">|</li>
									<li class="d-inline ml-2">回复 <i th:text="${map.post.commentCount}">7</i></li>
								</ul>
							</div>
						</div>
					</li>
				</ul>
Guo_Chuang
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