Java Web 项目学习 开发社区首页
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(一)DAO定义Mapper (Mybatis中的三步走)
- 实体类entity包下
package com.myproject.community.entity; import java.util.Date; public class DiscussPost { private int id; private int userId;//外键 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 + \'}\'; } }
- Mapper接口DAO包下
package com.myproject.community.dao; import com.myproject.community.entity.DiscussPost; import org.apache.ibatis.annotations.Mapper; import org.apache.ibatis.annotations.Param; import java.util.List; @Mapper public interface DiscussPostMapper { //分页查询数据,查询的可能是多条信息,因此返回的是一个集合 //userID针对个性化,搜索我查找的帖子,首页不会传Id,因此其实实现的是一个动态的sql //考虑到未来支持分页的可能性,mysql的分页十分简洁,加一个limit + 起始行行号offset + 分页展示多少条数据limit List<DiscussPost> selectDiscussPosts (int userId, int offset, int limit); //为了显示页码(查询的总条数/分页展示数据的条数limit),因此定义函数查询总的数据条数。同样动态sql //参数之前加注解 @Param("") 起别名,如果只有一个参数,并且在<if>中使用,则必须要有别名 // 若需要动态的拼一个条件(动态sql),且需要用的这个参数,并且方法有且只有一个参数,则必须要起别名! int selectDiscussPostRows(@Param("userId") int userId); }
- 配置文件xml,resource/mapper下
<?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"> <!--修改为自己的UerMapper的权限命名--> <mapper namespace="com.myproject.community.dao.UserMapper"> <!--写标签对应Mapper中的方法,#{id}表示java方法中的id--> <sql id="selectFields"> id, username, password, salt, email, type, status, activation_code, header_url, create_time </sql> <sql id="insertFields"> username, password, salt, email, type, status, activation_code, header_url, create_time </sql> <select id="selectById" resultType="User"> select <include refid="selectFields"></include> from user where id = #{id} </select> <select id="selectByName" resultType="User"> select <include refid="selectFields"></include> from user where username = #{username} </select> <select id="selectByEmail" resultType="User"> select <include refid="selectFields"></include> from user where email = #{email} </select> <!--参数不是java自带的,而是bean中的需要写parameterType,同时需要指明主键id,是Mybatis 从数据库中获取回填的,写对应User类中的属性--> <insert id="insertUser" parameterType="User" keyProperty="id"> insert into user (<include refid="insertFields"></include>) values (#{username}, #{password}, #{salt}, #{email}, #{type}, #{status}, #{activationCode}, #{headerUrl}, #{createTime}) </insert> <update id="updateStatus"> update user set status = #{status} where id =#{id} </update> <update id="updateHeader"> update user set header_url = #{headerUrl} where id =#{id} </update> <update id="updataPassword"> update user set password = #{password} where id =#{id} </update> </mapper>
(二)Service依赖DAO @Service 私有变量中声明对应Mapper,@Autowired
DiscussPostService
package com.myproject.community.service; import com.myproject.community.dao.DiscussPostMapper; import com.myproject.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); } }
UserService
package com.myproject.community.service; import com.myproject.community.dao.UserMapper; import com.myproject.community.entity.User; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; @Service public class UserService { @Autowired private UserMapper userMapper; //根据用户id查询用户名 public User findUserById(int id){ return userMapper.selectById(id); } }
(三)Controller依赖Service @Controller 私有变量中声明对应Service,@Autowired (具体见Spring Ioc)
- 注解 @RequestMapping(path = "/index",method = RequestMethod.GET)
- 成员函数,在函数体内,要将结果放入model中。
public String getIndexPage(Model model){ List <> discussPosts; .............. //将追踪的,要给页面展示的结果放到model中 model.addAttribute(起名字,对应的值) model.addAttribute("discussPosts",discussPosts); return "/index"; }
先写内容
package com.myproject.community.controller; import com.myproject.community.entity.DiscussPost; import com.myproject.community.entity.Page; import com.myproject.community.entity.User; import com.myproject.community.service.DiscussPostService; import com.myproject.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 org.springframework.web.bind.annotation.ResponseBody; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; @Controller public class HomeController { @Autowired private UserService userService; @Autowired private DiscussPostService discussPostService; @RequestMapping(path = "/index",method = RequestMethod.GET) public String getIndexPage(Model model, Page page){ List<DiscussPost> list = discussPostService.findDiscussPosts(0,0,0); //查到的数据只是UserId,而我们需要对应的名字,因此新建一个list,针对每一个DiscussPost,根据id查到User,组装数据 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); } } //将追踪的,要给页面展示的结果放到model中 model.addAttribute(起名字,对应的值) model.addAttribute("discussPosts",discussPosts); return "/index"; } }
再补写分页情况(增加Page实体,修改controller)
controller
@RequestMapping(path = "/index",method = RequestMethod.GET) public String getIndexPage(Model model, Page page){ page.setRows(discussPostService.findDiscussPostRows(0)); page.setPath("/index"); List<DiscussPost> list = discussPostService.findDiscussPosts(0,page.getOffset(),page.getLimit()); //查到的数据只是UserId,而我们需要对应的名字,因此新建一个list,针对每一个DiscussPost,根据id查到User,组装数据 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); } } //将追踪的,要给页面展示的结果放到model中 model.addAttribute(起名字,对应的值) model.addAttribute("discussPosts",discussPosts); //可以不用写。调用方法栈,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对象的数据 //model.addAttribute("page",page) return "/index"; }
Page
package com.myproject.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, (用于计算页面总数) private int rows ; //查询路径(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 */ public int getTotal(){ // row/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; } /** *获取终止页码 * @return */ public int getTo(){ int to = current +2; return to > getTotal() ? getTotal() :to; } }
(四)找对应的html文件,进行修改。(采用thymeleaf模板)
- 在html标签添加 <html lang="en" xmlns:th="http://www.thymeleaf.org">
- 对于相对路径 <link rel="stylesheet" th:href="@{/css/global.css}" /> 告诉th模板语言,去static静态目录下找/css/global.css
- 模板语言变量采用 ${} 表示
- 循环 th:each="map:${discussPosts}"
- 条件 th:if="${map.post.type==1}" ,只有条件成立时,才会显示。map.post.type其实是通过thymeleaf调用的map.key(post)找到对应的value值post.调用post.getType()方法得到值。
- text和utext的区别,utext可针对转移字符以常人理解的方式显示,text以转义字符的形式显示。
- datas格式 <b th:text="${#dates.format(map.post.createTime,\'yyyy-MM-dd HH:mm:ss\')}"> thymeleaf自带的格式化方式。
-
<a class="page-link" th:href="@{${page.path}(current=1,limit=10)}">首页</a>
相当于书写 index?current=1&limit=10
- 当既还有静态又含有动态变量时,用 |静 动 | 把他们框住,后面条件判断相等添加disabled <li th:class="|page-item ${page.current==page.total?\'disabled\':\'\'}|">
- thymeleaf自带 #numbers。sequence(a,b) 返回从a开始到b结束的连续的自然数。因为整体函数用 ${}表示了,所以a,b必为变量。不用加 用 ${} 。同时 i 为循环变量
<li th:class="|page-item ${i==page.current?\'active\':\'\'}|" th:each="i:${#numbers.sequence(page.from,page.to)}">
对应帖子的修改
<!-- 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="${#dates.format(map.post.createTime,\'yyyy-MM-dd HH:mm:ss\')}">2019-04-15 15:32:18</b> <ul class="d-inline float-right"> <li class="d-inline ml-2">赞 11</li> <li class="d-inline ml-2">|</li> <li class="d-inline ml-2">回帖 7</li> </ul> </div> </div> </li> </ul>
效果如图:
对应分页的修改
<!-- 分页 --> <!-- 没事有数据不显示 --> <nav class="mt-5" th:if="${page.rows>0}"> <ul class="pagination justify-content-center"> <li class="page-item"> <!-- index?current=1&limit=5 --> <a class="page-link" th:href="@{${page.path}(current=1,limit=10)}">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> &l以上是关于Java Web 项目学习 开发社区首页的主要内容,如果未能解决你的问题,请参考以下文章
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