13. 带你实现购物车功能

180 字约 1 分钟读完2461 次阅读更新于 2026/5/3

SQL

CREATE TABLE `cart` (
  `id` int NOT NULL AUTO_INCREMENT COMMENT '主键ID',
  `goods_id` int DEFAULT NULL COMMENT '商品ID',
  `num` int DEFAULT NULL COMMENT '数量',
  `user_id` int DEFAULT NULL COMMENT '用户ID',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci COMMENT='购物车信息';

开发后端接口

Cart.java

package com.example.entity;

import java.math.BigDecimal;

public class Cart {

    /**主键ID */
    private Integer id;
    /**商品ID */
    private Integer goodsId;
    private String goodsName;
    private String goodsImg;
    private BigDecimal goodsPrice;
    /**数量 */
    private Integer num;
    /**用户ID */
    private Integer userId;

    public BigDecimal getGoodsPrice() {
        return goodsPrice;
    }

    public void setGoodsPrice(BigDecimal goodsPrice) {
        this.goodsPrice = goodsPrice;
    }

    public String getGoodsImg() {
        return goodsImg;
    }

    public void setGoodsImg(String goodsImg) {
        this.goodsImg = goodsImg;
    }

    public String getGoodsName() {
        return goodsName;
    }

    public void setGoodsName(String goodsName) {
        this.goodsName = goodsName;
    }

    public Integer getId() {
        return id;
    }

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

    public Integer getGoodsId() {
        return goodsId;
    }

    public void setGoodsId(Integer goodsId) {
        this.goodsId = goodsId;
    }

    public Integer getNum() {
        return num;
    }

    public void setNum(Integer num) {
        this.num = num;
    }

    public Integer getUserId() {
        return userId;
    }

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

CartMapper.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.example.mapper.CartMapper">

    <select id="selectAll" resultType="com.example.entity.Cart">
        select cart.*, goods.name as goodsName, goods.img as goodsImg, goods.price as goodsPrice from `cart`
        left join goods on cart.goods_id = goods.id
        <where>
            <if test="userId != null"> and cart.user_id = #{userId}</if>
        </where>
        order by cart.id desc
    </select>

    <select id="selectById" resultType="com.example.entity.Cart">
        select * from `cart` where id = #{id}
    </select>

    <delete id="deleteById">
        delete from `cart` where id = #{id}
    </delete>

    <insert id="insert" parameterType="com.example.entity.Cart" useGeneratedKeys="true">
        insert into `cart`
        <trim prefix="(" suffix=")" suffixOverrides=",">
            <if test="id != null">id,</if>
            <if test="goodsId != null">goods_id,</if>
            <if test="num != null">num,</if>
            <if test="userId != null">user_id,</if>
        </trim>
        values
        <trim prefix="(" suffix=")" suffixOverrides=",">
            <if test="id != null">#{id},</if>
            <if test="goodsId != null">#{goodsId},</if>
            <if test="num != null">#{num},</if>
            <if test="userId != null">#{userId},</if>
        </trim>
    </insert>

    <update id="updateById" parameterType="com.example.entity.Cart">
        update `cart`
        <set>
            <if test="id != null">
                id = #{id},
            </if>
            <if test="goodsId != null">
                goods_id = #{goodsId},
            </if>
            <if test="num != null">
                num = #{num},
            </if>
            <if test="userId != null">
                user_id = #{userId},
            </if>
        </set>
        where id = #{id}
    </update>

</mapper>

详情页 addCart

const addCart = () => {
  request.post('/cart/add', { goodsId: data.id, num: data.num, userId: data.user.id }).then(res => {
    if (res.code === '200') {
      ElMessage.success('加入购物车成功')
    } else {
      ElMessage.error(res.msg)
    }
  })
}

删除或者下架商品需要删除对应购物车的商品

/**
 * 删除
 */
@Transactional
public void deleteById(Integer id) {
    goodsMapper.deleteById(id);
    // 删除购物车的对应的商品
    cartMapper.deleteByGoodsId(id);
}

/**
 * 修改
 */
public void updateById(Goods goods) {
    goodsMapper.updateById(goods);
    if (goods.getStatus().equals("下架")) {
        // 删除购物车的对应的商品
        cartMapper.deleteByGoodsId(goods.getId());
    }
}

前端页面

Cart.vue

<template>
  <div class="front-container">
    <div class="card" style="padding: 20px">
      <div>
        <el-table :data="data.tableData" stripe @selection-change="handleSelectionChange">
          <el-table-column type="selection" width="55" />
          <el-table-column label="商品图片">
            <template #default="scope">
              <img style="width: 50px; height: 50px; display: block" :src="scope.row.goodsImg" alt="">
            </template>
          </el-table-column>
          <el-table-column label="商品名称" prop="goodsName"></el-table-column>
          <el-table-column label="商品单价">
            <template #default="scope">
              <b style="color: red">￥{{ scope.row.goodsPrice }}</b>
            </template>
          </el-table-column>
          <el-table-column label="商品数量">
            <template #default="scope">
              <el-input-number @change="calTotal" v-model="scope.row.num" :min="1" style="width: 150px"></el-input-number>
            </template>
          </el-table-column>
          <el-table-column label="操作" align="center" width="100">
            <template #default="scope">
              <el-button type="danger" @click="handleDelete(scope.row.id)">删除</el-button>
            </template>
          </el-table-column>
        </el-table>
      </div>
      <div style="text-align: right; margin-top: 20px; font-size: 20px">总价格：
        <b style="color: red; display: inline-block; min-width: 60px; text-align: left">{{ data.total }} 元</b>
        <div style="margin-top: 10px"><el-button @click="addOrder" type="danger">立即下单</el-button></div>
      </div>
    </div>



    <el-dialog title="下单信息" width="30%" v-model="data.formVisible" :close-on-click-modal="false" destroy-on-close>
      <el-form ref="formRef" :model="data.form" :rules="data.rules" label-width="80px" style="padding-right: 30px; padding-top: 20px">
        <el-form-item label="名称" prop="name">
          <el-input v-model="data.form.name" autocomplete="off" />
        </el-form-item>
      </el-form>
      <template #footer>
      <span class="dialog-footer">
        <el-button @click="data.formVisible = false">取 消</el-button>
        <el-button type="primary" @click="save">保 存</el-button>
      </span>
      </template>
    </el-dialog>

  </div>
</template>

<script setup>
import request from "@/utils/request";
import {reactive, ref} from "vue";
import {ElMessageBox, ElMessage} from "element-plus";

const formRef = ref()
const data = reactive({
  user: JSON.parse(localStorage.getItem('system-user') || '{}'),
  total: 0,
  formVisible: false,
  form: {},
  tableData: [],
  selectedRows: [],
  rules: {
    name: [
      { required: true, message: '请输入名称', trigger: 'blur' },
    ]
  }
})

const calTotal = () => {
  data.total = 0
  // rows是选中行
  data.selectedRows.forEach(item => {
    data.total += item.goodsPrice * item.num
  })
  if (data.total > 0) {
    data.total = data.total.toFixed(2)
  }
}

const handleSelectionChange = (rows) => {
  data.selectedRows = rows
  calTotal()
}

// 分页查询
const load = () => {
  request.get('/cart/selectAll', {
    params: {
      userId: data.user.id
    }
  }).then(res => {
    data.tableData = res.data
  })
}
load()

// 新增
const handleAdd = () => {
  data.form = {}
  data.formVisible = true
}

// 编辑
const handleEdit = (row) => {
  data.form = JSON.parse(JSON.stringify(row))
  data.formVisible = true
}

// 新增保存
const add = () => {
  request.post('/cart/add', data.form).then(res => {
    if (res.code === '200') {
      load()
      ElMessage.success('操作成功')
      data.formVisible = false
    } else {
      ElMessage.error(res.msg)
    }
  })
}

// 编辑保存
const update = () => {
  request.put('/cart/update', data.form).then(res => {
    if (res.code === '200') {
      load()
      ElMessage.success('操作成功')
      data.formVisible = false
    } else {
      ElMessage.error(res.msg)
    }
  })
}

// 弹窗保存
const save = () => {
  formRef.value.validate(valid => {
    if (valid) {
      // data.form有id就是更新，没有就是新增
      data.form.id ? update() : add()
    }
  })
}

// 删除
const handleDelete = (id) => {
  ElMessageBox.confirm('您确定删除吗?', '删除确认', { type: 'warning' }).then(res => {
    request.delete('/cart/delete/' + id).then(res => {
      if (res.code === '200') {
        load()
        ElMessage.success('操作成功')
      } else {
        ElMessage.error(res.msg)
      }
    })
  }).catch(err => {})
}

// 重置
const reset = () => {
  data.name = null
  load()
}
</script>

SQL

开发后端接口

详情页 addCart

删除或者下架商品需要删除对应购物车的商品

前端页面

我们只查询上架的商品