注：代码来自于若依框架—RuoYi-master
控制器层核心代码

 @GetMapping("/edit/{customerId}")
    public String edit(@PathVariable("customerId") Long customerId, ModelMap mmap)
    {
        SysCustomer sysCustomer = sysCustomerService.selectSysCustomerByCustomerId(customerId);  //根据id查询返回sysCustomer
        mmap.put("sysCustomer", sysCustomer); 
        return prefix + "/edit";
    }

实体类：

public class CustomerModel
{
    /**
     * 客户姓名
     */
    private String name;

    /**
     * 客户手机
     */
    private String phonenumber;

    /**
     * 客户性别
     */
    private String sex;

    /**
     * 客户生日
     */
    private String birthday;

    /**
     * 客户描述
     */
    private String remark;

    /**
     * 商品信息
     */
    private List<GoodsModel> goods;

    public String getName()
    {
        return name;
    }

    public void setName(String name)
    {
        this.name = name;
    }

    public String getPhonenumber()
    {
        return phonenumber;
    }

    public void setPhonenumber(String phonenumber)
    {
        this.phonenumber = phonenumber;
    }


    public String getSex()
    {
        return sex;
    }

    public void setSex(String sex)
    {
        this.sex = sex;
    }

    public String getBirthday()
    {
        return birthday;
    }

    public void setBirthday(String birthday)
    {
        this.birthday = birthday;
    }

    public String getRemark()
    {
        return remark;
    }

    public void setRemark(String remark)
    {
        this.remark = remark;
    }

    public List<GoodsModel> getGoods()
    {
        return goods;
    }

    public void setGoods(List<GoodsModel> goods)
    {
        this.goods = goods;
    }

    @Override
    public String toString() {
        return new ToStringBuilder(this,ToStringStyle.MULTI_LINE_STYLE)
            .append("name", getName())
            .append("phonenumber", getPhonenumber())
            .append("sex", getSex())
            .append("birthday", getBirthday())
            .append("goods", getGoods())
            .append("remark", getRemark())
            .toString();
    }
}

视图层

 <form class="form-horizontal m" id="form-customer-edit" th:object="${sysCustomer}">
            <input name="customerId" th:field="*{customerId}" type="hidden">
            <div class="form-group">
                <label class="col-sm-3 control-label">客户姓名：</label>
                <div class="col-sm-8">
                    <input name="customerName" th:field="*{customerName}" class="form-control" type="text">
                </div>
            </div>
            <div class="form-group">
                <label class="col-sm-3 control-label">手机号码：</label>
                <div class="col-sm-8">
                    <input name="phonenumber" th:field="*{phonenumber}" class="form-control" type="text">
                </div>
            </div>
            <div class="form-group">
                <label class="col-sm-3 control-label">客户性别：</label>
                <div class="col-sm-8">
                    <select name="sex" class="form-control m-b" th:with="type=${@dict.getType('sys_customer_sex')}">
                        <option th:each="dict : ${type}" th:text="${dict.dictLabel}" th:value="${dict.dictValue}"></option>
                    </select>
                </div>
            </div>
            <div class="form-group">
                <label class="col-sm-3 control-label">客户生日：</label>
                <div class="col-sm-8">
                    <div class="input-group date">
                        <input name="birthday" th:value="${#dates.format(sysCustomer.birthday, 'yyyy-MM-dd')}" class="form-control" placeholder="yyyy-MM-dd" type="text">
                        <span class="input-group-addon"><i class="fa fa-calendar"></i></span>
                    </div>
                </div>
            </div>
            <div class="form-group">
                <label class="col-sm-3 control-label">客户描述：</label>
                <div class="col-sm-8">
                    <textarea name="remark" class="form-control">[[*{remark}]]</textarea>
                </div>
            </div>
        </form>

核心：
前端标签内通过th:object="${sysCustomer}"接收ModelMap传来的实体类，然后再th:field="*{customerId}"标签来获取实体类内的各个属性