Spring Edit功能在页面中插入新元素，而不是更新旧元素

Question

我开始学习春季，我想创建一个电子商务商店。我在项目中使用spring + mysql。 到目前为止，我设法实现了Create，Read和Delete，但是说真的Update无法正常工作，我不知道该怎么办...

这是我的代码：

HomeController.class

@RequestMapping("/admin/productInventory/editProduct/{id}")
public String editProduct(@PathVariable("id") Long id, Model model) {
Product product = productDAO.getProductByID(id);
model.addAttribute(product);
return "editProduct";
}
@RequestMapping(value = "/admin/productInventory/editProduct", method = RequestMethod.POST)
public String editProductPost(@ModelAttribute("product") Product product) {
productDAO.editProduct(product);
return "redirect:/admin/productInventory";
}

在ProductDAOImplementation.class中编辑产品功能

public void editProduct(Product product) {
Session session = sessionFactory.getCurrentSession();
session.saveOrUpdate(product);
session.flush();
}

这是我的editProduct.jsp

<%@taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@include file="/WEB-INF/view/template/header.jsp" %>


<div class="container-wrapper">
<div class="container">
<div class="page-header">
<h1>Edit Product</h1>
<p class="lead">Please update the product information here:</p>
</div>
<form:form action="${pageContext.request.contextPath}/admin/productInventory/editProduct" method="post"
               commandName="product" enctype="multipart/form-data">
        <form:hidden path="productID" value="${product.productID}" />
    <div class="form-group">
        <label for="name">Name:</label>
        <form:input path="productName" id="name" class="form-Control" value="${product.productName}"/>
    </div>
    <div class="form-group">
        <label for="category">Category:</label>
        <label class="checkbox-inline"><form:radiobutton path="productCategory" id="category"
                                                         value="sneakers" />Sneakers</label>
        <label class="checkbox-inline"><form:radiobutton path="productCategory" id="category"
                                                         value="shoes" />Shoes</label>
        <label class="checkbox-inline"><form:radiobutton path="productCategory" id="category"
                                                         value="boots" />Boots</label>
    </div>
    <div class="form-group">
        <label for="description">Description</label>
        <form:textarea path="productDescription" id="description" class="form-Control" value="${product.productDescription}"/>
    </div>
    <div class="form-group">
        <label for="category"></label>
        <label class="checkbox-inline"><form:radiobutton path="productSize" id="size"
                                                         value="40" />40</label>
        <label class="checkbox-inline"><form:radiobutton path="productSize" id="size"
                                                         value="41" />41</label>
        <label class="checkbox-inline"><form:radiobutton path="productSize" id="size"
                                                         value="42" />42</label
        <label class="checkbox-inline"><form:radiobutton path="productSize" id="size"
                                                         value="43" />43</label>
        <label class="checkbox-inline"><form:radiobutton path="productSize" id="size"
                                                         value="44" />44</label>
    </div>
    <div class="form-group">
        <label for="price">Price</label>
        <form:input path="productPrice" id="price" class="form-Control" value="${product.productPrice}"/>
    </div>
    <div class="form-group">
        <label for="status">Status</label>
        <label class="checkbox-inline"><form:radiobutton path="productStatus" id="status"
                                                         value="active" />Active</label>
        <label class="checkbox-inline"><form:radiobutton path="productStatus" id="status"
                                                         value="inactive" />Inactive</label>
    </div>
    <div class="form-group">
        <label for="quantity">Quantity</label>
        <form:input path="productQuantity" id="quantity" class="form-Control" value="${product.productQuantity}"/>
    </div>
    <div class="form-group">
        <label for="manufacturer">Manufacturer</label>
        <form:input path="productManufacturer" id="manufacturer" class="form-Control" value="${product.productManufacturer}"/>
    </div>
    <br><br>
    <input type="submit" value="Submit" class="btn btn-default">
    <a href="<c:url value="/admin/productInventory" />" class="btn btn-default">Cancel</a>
    </form:form>
    <%@include file="/WEB-INF/view/template/footer.jsp" %>

有人说我应该添加隐藏路径以获取当前的productID 但它仍会创建一个空元素。 有什么建议吗？