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[Java知识库]牛客网项目——项目开发（二）：开发社区首页

文章目录

1. DAO层开发
2. SERVICE层开发
- 2.1 在service包下新建业务组件DiscussPostService
- 2.2 在service包下新建业务组件UserService
3. 视图层开发

1. DAO层开发

1.1 数据库信息

在这里插入图片描述

1.2 在entity中新建 DiscussPost 实体类

package com.nowcoder.community.entity;

import java.util.Date;

public class DiscussPost {

    private int id;
    private int userId;
    private String title;
    private String content;
    private int type;
    private int status;
    private Date createTime;
    private int commentCount;
    private double score;

    public int getId() {
        return id;
    }

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

    public int getUserId() {
        return userId;
    }

    public void setUserId(int userId) {
        this.userId = userId;
    }

    public String getTitle() {
        return title;
    }

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

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public int getType() {
        return type;
    }

    public void setType(int type) {
        this.type = type;
    }

    public int getStatus() {
        return status;
    }

    public void setStatus(int status) {
        this.status = status;
    }

    public Date getCreateTime() {
        return createTime;
    }

    public void setCreateTime(Date createTime) {
        this.createTime = createTime;
    }

    public int getCommentCount() {
        return commentCount;
    }

    public void setCommentCount(int commentCount) {
        this.commentCount = commentCount;
    }

    public double getScore() {
        return score;
    }

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

    @Override
    public String toString() {
        return "DiscussPost{" +
                "id=" + id +
                ", userId=" + userId +
                ", title='" + title + '\'' +
                ", content='" + content + '\'' +
                ", type=" + type +
                ", status=" + status +
                ", createTime=" + createTime +
                ", commentCount=" + commentCount +
                ", score=" + score +
                '}';
    }
}

1.3 在dao中创建 DiscussPostMapper接口

定义两个方法

返回查到的帖子
返回帖子行数

package com.nowcoder.community.dao;

import com.nowcoder.community.entity.DiscussPost;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;

import java.util.List;

@Mapper
public interface DiscussPostMapper {

    List<DiscussPost> selectDiscussPosts(int userId, int offset, int limit);

    // @Param注解用于给参数取别名,
    // 如果只有一个参数,并且在<if>里使用,则必须加别名.
    int selectDiscussPostRows(@Param("userId") int userId);

}

1.4 在mapper下创建discusspost-mapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.nowcoder.community.dao.DiscussPostMapper">

    <sql id="selectFields">
        id, user_id, title, content, type, status, create_time, comment_count, score
    </sql>

    <select id="selectDiscussPosts" resultType="DiscussPost">
        select <include refid="selectFields"></include>
        from discuss_post
        where status != 2
        <if test="userId!=0">
            and user_id = #{userId}
        </if>
        order by type desc, create_time desc
        limit #{offset}, #{limit}
    </select>

    <select id="selectDiscussPostRows" resultType="int">
        select count(id)
        from discuss_post
        where status != 2
        <if test="userId!=0">
            and user_id = #{userId}
        </if>
    </select>

</mapper>

1.5 dao层测试

    @Autowired
    private DiscussPostMapper discussPostMapper;
    
	@Test
    public void testSelectPosts() {
        List<DiscussPost> list = discussPostMapper.selectDiscussPosts(149, 0, 10);
        for(DiscussPost post : list) {
            System.out.println(post);
        }

        int rows = discussPostMapper.selectDiscussPostRows(149);
        System.out.println(rows);
    }

在这里插入图片描述

2. SERVICE层开发

2.1 在service包下新建业务组件DiscussPostService

即使简单也不要跨层调用
针对每一个DiscussPost，查询user进行拼接
需要一个userservice

package com.nowcoder.community.service;

import com.nowcoder.community.dao.DiscussPostMapper;
import com.nowcoder.community.entity.DiscussPost;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class DiscussPostService {

    @Autowired
    private DiscussPostMapper discussPostMapper;

    public List<DiscussPost> findDiscussPosts(int userId, int offset, int limit) {
        return discussPostMapper.selectDiscussPosts(userId, offset, limit);
    }

    public int findDiscussPostRows(int userId) {
        return discussPostMapper.selectDiscussPostRows(userId);
    }

}

2.2 在service包下新建业务组件UserService

package com.nowcoder.community.service;

import com.nowcoder.community.dao.UserMapper;
import com.nowcoder.community.entity.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class UserService {

    @Autowired
    private UserMapper userMapper;

    public User findUserById(int id) {
        return userMapper.selectById(id);
    }

}

3. 视图层开发

取消勾选显示中间层
在这里插入图片描述

3.1 样式文件，图片，js这些静态资源粘贴到static下

在这里插入图片描述

3.2 mail，site，index.xml粘贴到templates之下

在这里插入图片描述

拷贝完后可以让空包不显示

3.3 在controller下实现HomeController

访问路径 /index

package com.nowcoder.community.controller;

import com.nowcoder.community.entity.DiscussPost;
import com.nowcoder.community.entity.Page;
import com.nowcoder.community.entity.User;
import com.nowcoder.community.service.DiscussPostService;
import com.nowcoder.community.service.UserService;
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 HomeController {

    @Autowired
    private DiscussPostService discussPostService;

    @Autowired
    private UserService userService;

    @RequestMapping(path = "/index", method = RequestMethod.GET)
    public String getIndexPage(Model model) {
        List<DiscussPost> list = discussPostService.findDiscussPosts(0, 0, 10);
        List<Map<String, Object>> discussPosts = new ArrayList<>();
        if (list != null) {
            for (DiscussPost post : list) {
                Map<String, Object> map = new HashMap<>();
                map.put("post", post);
                User user = userService.findUserById(post.getUserId());
                map.put("user", user);
                discussPosts.add(map);
            }
        }
        model.addAttribute("discussPosts", discussPosts);
        return "/index";
    }

}

3.4 实现index.html

3.4.1 路径修改

开头先指定模板引擎

<html lang="en" xmlns:th="http://www.thymeleaf.org">

依赖的样式文件和图片绝对路径不用改，相对路径修改方式如下

<!-- 修改前 -->
<link rel="stylesheet" href="css/global.css" />

<!-- 修改后，去static下寻找资源 -->
<link rel="stylesheet" th:href="@{/css/global.css}" />

3.4.2 处理帖子列表页面

留一个li，使用each遍历输出

<li class="media pb-3 pt-3 mb-3 border-bottom" th:each="map:${discussPosts}"></li>

用户头像

<img th:src="${map.user.headerUrl}" class="mr-4 rounded-circle" alt="用户头像" style="width:50px;height:50px;">

帖子标题

<!-- utext相比text不处理转义字符 -->
<a href="#" th:utext="${map.post.title}">备战春招，面试刷题跟他复习，一个月全搞定！</a>

置顶和精华，通过判断

<span class="badge badge-secondary bg-primary" th:if="${map.post.type==1}">置顶</span>
<span class="badge badge-secondary bg-danger" th:if="${map.post.status==1}">精华</span>

帖子作者和发布时间

<!-- #dates的#意思是使用 -->
<u class="mr-3" th:utext="${map.user.username}">寒江雪</u> 发布于 <b th:text="${#dates.format(map.post.createTime,'yyyy-MM-dd HH:mm:ss')}">2019-04-15 15:32:18</b>

3.4.3 封装分页相关信息类

在entity下实现Page封装分页相关的信息

package com.nowcoder.community.entity;

/**
 * 封装分页相关的信息.
 */
public class Page {

    // 当前页码
    private int current = 1;
    // 显示上限
    private int limit = 10;
    // 数据总数(用于计算总页数)
    private int rows;
    // 查询路径(用于复用分页链接)
    private String path;

    public int getCurrent() {
        return current;
    }

    public void setCurrent(int current) {
        if (current >= 1) {
            this.current = current;
        }
    }

    public int getLimit() {
        return limit;
    }

    public void setLimit(int limit) {
        if (limit >= 1 && limit <= 100) {
            this.limit = limit;
        }
    }

    public int getRows() {
        return rows;
    }

    public void setRows(int rows) {
        if (rows >= 0) {
            this.rows = rows;
        }
    }

    public String getPath() {
        return path;
    }

    public void setPath(String path) {
        this.path = path;
    }

    /**
     * 获取当前页的起始行
     *
     * @return
     */
    public int getOffset() {
        // current * limit - limit
        return (current - 1) * limit;
    }

    /**
     * 获取总页数
     *
     * @return
     */
    public int getTotal() {
        // rows / limit [+1]
        if (rows % limit == 0) {
            return rows / limit;
        } else {
            return rows / limit + 1;
        }
    }

    /**
     * 获取起始页码
     *
     * @return
     */
    public int getFrom() {
        int from = current - 2;
        return from < 1 ? 1 : from;
    }

    /**
     * 获取结束页码
     *
     * @return
     */
    public int getTo() {
        int to = current + 2;
        int total = getTotal();
        return to > total ? total : to;
    }

}

改造HomeController的查询方法，增加page相关内容

 	@RequestMapping(path = "/index", method = RequestMethod.GET)
    public String getIndexPage(Model model, Page page) {
        // 方法调用钱,SpringMVC会自动实例化Model和Page,并将Page注入Model.
        // 所以,在thymeleaf中可以直接访问Page对象中的数据.
        page.setRows(discussPostService.findDiscussPostRows(0));
        page.setPath("/index");

        List<DiscussPost> list = discussPostService.findDiscussPosts(0, page.getOffset(), page.getLimit());
        List<Map<String, Object>> discussPosts = new ArrayList<>();
        if (list != null) {
            for (DiscussPost post : list) {
                Map<String, Object> map = new HashMap<>();
                map.put("post", post);
                User user = userService.findUserById(post.getUserId());
                map.put("user", user);
                discussPosts.add(map);
            }
        }
        model.addAttribute("discussPosts", discussPosts);
        return "/index";
    }

3.4.4 index.html分页逻辑

对整个分页数据，先判断是否有数据需要显示，判断page中行数是否大于0

<nav class="mt-5" th:if="${page.rows>0}"></nav>

首页末页逻辑

<li class="page-item">
	<a class="page-link" th:href="@{${page.path}(current=1)}">首页</a>
</li>

<li class="page-item">
	<a class="page-link" th:href="@{${page.path}(current=page.total)}">末页</a>
</li>

上一页下一页逻辑，第一页的时候上一页不可点，最后一页的时候末尾页不可点

<li th:class="|page-item ${page.current==1?'disabled':''}|">
	<a class="page-link" th:href="@{${page.path}(current=${page.current-1})}">上一页</a>
</li>

<li th:class="|page-item ${page.current==page.total?'disabled':''}|">
	<a class="page-link" th:href="@{${page.path}(current=${page.current+1})}">下一页</a>
</li>

当前页逻辑

<li th:class="|page-item ${i==page.current?'active':''}|" 	th:each="i:${#numbers.sequence(page.from,page.to)}">
	<a class="page-link" href="#" th:text="${i}">1</a>
</li>

在这里插入图片描述

完整index.html

<!doctype html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
	<link rel="icon" href="https://static.nowcoder.com/images/logo_87_87.png"/>
	<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" crossorigin="anonymous">
	<link rel="stylesheet" th:href="@{/css/global.css}" />
	<title>牛客网-首页</title>
</head>
<body>	
	<div class="nk-container">
		<!-- 头部 -->
		<header class="bg-dark sticky-top">
			<div class="container">
				<!-- 导航 -->
				<nav class="navbar navbar-expand-lg navbar-dark">
					<!-- logo -->
					<a class="navbar-brand" href="#"></a>
					<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
						<span class="navbar-toggler-icon"></span>
					</button>
					<!-- 功能 -->
					<div class="collapse navbar-collapse" id="navbarSupportedContent">
						<ul class="navbar-nav mr-auto">
							<li class="nav-item ml-3 btn-group-vertical">
								<a class="nav-link" href="index.html">首页</a>
							</li>
							<li class="nav-item ml-3 btn-group-vertical">
								<a class="nav-link position-relative" href="site/letter.html">消息<span class="badge badge-danger">12</span></a>
							</li>
							<li class="nav-item ml-3 btn-group-vertical">
								<a class="nav-link" href="site/register.html">注册</a>
							</li>
							<li class="nav-item ml-3 btn-group-vertical">
								<a class="nav-link" href="site/login.html">登录</a>
							</li>
							<li class="nav-item ml-3 btn-group-vertical dropdown">
								<a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
									<img src="http://images.nowcoder.com/head/1t.png" class="rounded-circle" style="width:30px;"/>
								</a>
								<div class="dropdown-menu" aria-labelledby="navbarDropdown">
									<a class="dropdown-item text-center" href="site/profile.html">个人主页</a>
									<a class="dropdown-item text-center" href="site/setting.html">账号设置</a>
									<a class="dropdown-item text-center" href="site/login.html">退出登录</a>
									<div class="dropdown-divider"></div>
									<span class="dropdown-item text-center text-secondary">nowcoder</span>
								</div>
							</li>
						</ul>
						<!-- 搜索 -->
						<form class="form-inline my-2 my-lg-0" action="site/search.html">
							<input class="form-control mr-sm-2" type="search" aria-label="Search" />
							<button class="btn btn-outline-light my-2 my-sm-0" type="submit">搜索</button>
						</form>
					</div>
				</nav>
			</div>
		</header>

		<!-- 内容 -->
		<div class="main">
			<div class="container">
				<div class="position-relative">
					<!-- 筛选条件 -->
					<ul class="nav nav-tabs mb-3">
						<li class="nav-item">
							<a class="nav-link active" href="#">最新</a>
						</li>
						<li class="nav-item">
							<a class="nav-link" href="#">最热</a>
						</li>
					</ul>
					<button type="button" class="btn btn-primary btn-sm position-absolute rt-0" data-toggle="modal" data-target="#publishModal">我要发布</button>
				</div>
				<!-- 弹出框 -->
				<div class="modal fade" id="publishModal" tabindex="-1" role="dialog" aria-labelledby="publishModalLabel" aria-hidden="true">
					<div class="modal-dialog modal-lg" role="document">
						<div class="modal-content">
							<div class="modal-header">
								<h5 class="modal-title" id="publishModalLabel">新帖发布</h5>
								<button type="button" class="close" data-dismiss="modal" aria-label="Close">
									<span aria-hidden="true">&times;</span>
								</button>
							</div>
							<div class="modal-body">
								<form>
									<div class="form-group">
										<label for="recipient-name" class="col-form-label">标题：</label>
										<input type="text" class="form-control" id="recipient-name">
									</div>
									<div class="form-group">
										<label for="message-text" class="col-form-label">正文：</label>
										<textarea class="form-control" id="message-text" rows="15"></textarea>
									</div>
								</form>
							</div>
							<div class="modal-footer">
								<button type="button" class="btn btn-secondary" data-dismiss="modal">取消</button>
								<button type="button" class="btn btn-primary" id="publishBtn">发布</button>
							</div>
						</div>
					</div>
				</div>
				<!-- 提示框 -->
				<div class="modal fade" id="hintModal" tabindex="-1" role="dialog" aria-labelledby="hintModalLabel" aria-hidden="true">
					<div class="modal-dialog modal-lg" role="document">
						<div class="modal-content">
							<div class="modal-header">
								<h5 class="modal-title" id="hintModalLabel">提示</h5>
							</div>
							<div class="modal-body" id="hintBody">
								发布完毕!
							</div>
						</div>
					</div>
				</div>
				
				<!-- 帖子列表 -->
				<ul class="list-unstyled">
					<li class="media pb-3 pt-3 mb-3 border-bottom" th:each="map:${discussPosts}">
						<a href="site/profile.html">
							<img th:src="${map.user.headerUrl}" class="mr-4 rounded-circle" alt="用户头像" style="width:50px;height:50px;">
						</a>
						<div class="media-body">
							<h6 class="mt-0 mb-3">
								<a href="#" th:utext="${map.post.title}">备战春招，面试刷题跟他复习，一个月全搞定！</a>
								<span class="badge badge-secondary bg-primary" th:if="${map.post.type==1}">置顶</span>
								<span class="badge badge-secondary bg-danger" th:if="${map.post.status==1}">精华</span>
							</h6>
							<div class="text-muted font-size-12">
								<u class="mr-3" th:utext="${map.user.username}">寒江雪</u> 发布于 <b th:text="${#dates.format(map.post.createTime,'yyyy-MM-dd HH:mm:ss')}">2019-04-15 15:32:18</b>
								<ul class="d-inline float-right">
									<li class="d-inline ml-2">赞 11</li>
									<li class="d-inline ml-2">|</li>
									<li class="d-inline ml-2">回帖 7</li>
								</ul>
							</div>
						</div>						
					</li>
				</ul>
				<!-- 分页 -->
				<nav class="mt-5" th:if="${page.rows>0}">
					<ul class="pagination justify-content-center">
						<li class="page-item">
							<a class="page-link" th:href="@{${page.path}(current=1)}">首页</a>
						</li>
						<li th:class="|page-item ${page.current==1?'disabled':''}|">
							<a class="page-link" th:href="@{${page.path}(current=${page.current-1})}">上一页</a></li>
						<li th:class="|page-item ${i==page.current?'active':''}|" th:each="i:${#numbers.sequence(page.from,page.to)}">
							<a class="page-link" href="#" th:text="${i}">1</a>
						</li>
						<li th:class="|page-item ${page.current==page.total?'disabled':''}|">
							<a class="page-link" th:href="@{${page.path}(current=${page.current+1})}">下一页</a>
						</li>
						<li class="page-item">
							<a class="page-link" th:href="@{${page.path}(current=${page.total})}">末页</a>
						</li>
					</ul>
				</nav>
			</div>
		</div>

		<!-- 尾部 -->
		<footer class="bg-dark">
			<div class="container">
				<div class="row">
					<!-- 二维码 -->
					<div class="col-4 qrcode">
						<img src="https://uploadfiles.nowcoder.com/app/app_download.png" class="img-thumbnail" style="width:136px;" />
					</div>
					<!-- 公司信息 -->
					<div class="col-8 detail-info">
						<div class="row">
							<div class="col">
								<ul class="nav">
									<li class="nav-item">
										<a class="nav-link text-light" href="#">关于我们</a>
									</li>
									<li class="nav-item">
										<a class="nav-link text-light" href="#">加入我们</a>
									</li>
									<li class="nav-item">
										<a class="nav-link text-light" href="#">意见反馈</a>
									</li>
									<li class="nav-item">
										<a class="nav-link text-light" href="#">企业服务</a>
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