牛客网项目——项目开发（二）：开发社区首页

1. DAO层开发

1.1 数据库信息

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

1. 返回查到的帖子
2. 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);
    }

2. SERVICE层开发

2.1 在service包下新建业务组件DiscussPostService

1. 即使简单也不要跨层调用
2. 针对每一个DiscussPost，查询user进行拼接
3. 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

3.1 样式文件，图片，js这些静态资源粘贴到static下

3.2 mail，site，index.xml粘贴到templates之下

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.Re