我是spring form和hibernate的新手，我有3个域对象：Product，Category和Supplier。每当我尝试在产品的页面上选择编辑链接时，都会出现以下异常。类别名称＆amp;供应商应显示在选择列表中，并且应将id值传递给属性。虽然添加操作和删除操作工作正常但不是编辑链接，但实际上必须使用将由用户选择的特定产品的值回发相同的页面。请帮忙。
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@ taglib prefix="springtags" uri="http://www.springframework.org/tags"%>
<%@ taglib uri="http://www.springframework.org/tags/form"
prefix="spring"%>
<%@ taglib prefix="springtags" uri="http://www.springframework.org/tags"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Product</title>
</head>
<body>
<%@ include file="header.jsp"%>
<br>
<br>
<br>
<div style="height: 300px; width: 500px; padding: 10px" align="center">
<spring:form method="POST"
action="${pageContext.request.contextPath}/addProduct" commandName="product">
<table cellpadding="5" cellspacing="10" style="background-color: pink;">
<tr>
<c:choose>
<c:when test="${! empty product.productname}">
<td><spring:label path="productid"><springtags:message text="Product ID :"></springtags:message></spring:label></td>
<td><spring:input path="productid" disabled="true" readonly="true" /></td>
</c:when>
<c:otherwise>
<td><spring:label path="productid"><springtags:message text="Product ID :"></springtags:message></spring:label></td>
<td><spring:input path="productid" /></td>
</c:otherwise>
</c:choose>
</tr>
<tr>
<td>Product Name :</td>
<td><spring:input path="productname" /></td>
</tr>
<tr>
<td>Product Description :</td>
<td><spring:input path="description" /></td>
</tr>
<tr>
<td>Product Price :</td>
<td><spring:input path="price" /></td>
</tr>
<tr>
<td>Category :</td>
<td><spring:select path="categoryid"
items="${categorylist}" itemValue="id" itemLabel="name">
</spring:select>
<td><spring:errors path="categoryid" cssClass="error" /></td>
</tr>
<tr>
<td>Supplier :</td>
<td><spring:select path="supplierid"
items="${supplierlist}" itemValue="id" itemLabel="name" />
<td><spring:errors path="supplierid" cssClass="error" /></td>
</tr>
<tr>
<td align="center">
<c:if test="${product.productid eq 0}">
<input type="submit" value="<springtags:message text="Add Product"/>" />
</c:if>
</td>
<td>
<c:if test="${product.productid ne 0}">
<input type="submit" value="<springtags:message text="Edit Product"/>" />
</c:if>
</td>
</tr>
</table>
</spring:form>
<div>
<p>${msg}</p>
</div>
<div class="container">
<table
class="table table-striped table-bordered table-hover table-condensed">
<caption>
<h2>Categories</h2>
</caption>
<thead>
<tr>
<th>Product ID</th>
<th>Product Name</th>
<th>Product Description</th>
<th>Product Price</th>
<th>Category Name</th>
<th>Supplier Name</th>
<th>Edit</th>
<th>Delete</th>
</tr>
</thead>
<c:if test="${not empty productlist}">
<tbody>
<c:forEach items="${productlist}" var="product">
<tr>
<td>${product.productid}</td>
<td>${product.productname}</td>
<td>${product.description}</td>
<td>${product.price}</td>
<td>${product.category.name}</td>
<td>${product.supplier.name }</td>
<td><a href="product/edit/${product.productid}">Edit</a></td>
<td><a href="product/delete/${product.productid}">Delete</a></td>
</tr>
</c:forEach>
</tbody>
</c:if>
<c:if test="${empty productlist}">
There are no product yet.
</c:if>
</tr>
</table>
</div>
</body>
package com.niit;
import java.util.List;
import com.niit.cakecuisinebe.model.Category;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.log4j.Logger;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PatchMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import com.niit.cakecuisinebe.model.Category;
import com.niit.cakecuisinebe.dao.CategoryDAO;
import com.niit.cakecuisinebe.dao.CategoryDAOImpl;
import com.niit.cakecuisinebe.dao.ProductDAO;
import com.niit.cakecuisinebe.dao.*;
import com.niit.cakecuisinebe.model.*;
@Controller
public class ProductController{
protected static Logger logger = Logger.getLogger("ProductController");
@Autowired
private ProductDAO productDao;
@Autowired
private CategoryDAO categoryDao;
@Autowired
private SupplierDAO supplierDao;
@RequestMapping(value = "/products", method = RequestMethod.GET)
public String getProduct(Model model) {
logger.info("entering showAllGreetings");
List<Category> categories=categoryDao.list();
List<Supplier> suppliers=supplierDao.list();
List<Product> products = productDao.list();
if (products!=null && !products.isEmpty()) {
model.addAttribute("product", new Product());
model.addAttribute("category", new Category());
model.addAttribute("supplier", new Supplier());
model.addAttribute("productlist", products);
model.addAttribute("categorylist",categories);
model.addAttribute("supplierlist",suppliers);
}
return "Product";
}
@RequestMapping(value = "/addProduct", method= RequestMethod.POST)
public String addProduct(@ModelAttribute("product") Product product ) {
logger.info("entering showAllGreetings");
/*System.out.println(product.getCategory().getId());
System.out.println(product.getSupplier().getId());
Category category = categoryDao.getByName(product.getCategory().getName());
categoryDao.saveOrUpdate(category);
Supplier supplier = supplierDao.getByName(product.getSupplier().getName());
supplierDao.saveOrUpdate(supplier);
product.setCategory(category);
product.setSupplier(supplier);
product.setCategoryid(category.getId());
product.setSupplierid(supplier.getId());*/
productDao.saveOrUpdate(product);
return "redirect:/products";
}
@RequestMapping(value = "/product/delete/{id}", method = RequestMethod.GET)
public String deleteProduct(@PathVariable("id")int id, ModelMap model) {
logger.info("entering showAllGreetings");
productDao.delete(id);
model.addAttribute("msg","Successfully Deleted");
return "redirect:/products";
}
@RequestMapping(value = "/product/edit/{id}", method = RequestMethod.GET)
public String showEditProduct(@PathVariable("id") int id, ModelMap model ) {
logger.info("entering showAllGreetings");
Product productToUpdate=this.productDao.get(id);
model.addAttribute("product", this.productDao.get(id));
model.addAttribute("category", this.categoryDao.get(productToUpdate.getCategoryid()));
model.addAttribute("supplier", this.supplierDao.get(productToUpdate.getSupplierid()));
model.addAttribute("productlist", productDao.list());
model.addAttribute("categorylist",this.categoryDao.list());
model.addAttribute("supplierlist",this.productDao.list());
return "Product";
}
}
package com.niit.cakecuisinebe.model;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToMany;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
import org.springframework.stereotype.Component;
@Entity
@Table
@Component
public class Product {
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
private int productid;
private String productname;
private String description;
private double price;
private int categoryid;
private int supplierid;
public int getCategoryid() {
return categoryid;
}
public void setCategoryid(int category_id) {
this.categoryid = category_id;
}
public int getSupplierid() {
return supplierid;
}
public void setSupplierid(int supplier_id) {
this.supplierid = supplier_id;
}
@ManyToOne
@JoinColumn(name="categoryid",nullable = false, updatable = false, insertable = false)
private Category category;
@ManyToOne
@JoinColumn(name="supplierid",nullable = false, updatable =false, insertable = false)
private Supplier supplier;
public Category getCategory() {
return category;
}
public void setCategory(Category category) {
this.category= category;
}
public Supplier getSupplier() {
return supplier;
}
public void setSupplier(Supplier supplier) {
this.supplier= supplier;
}
public int getProductid() {
return productid;
}
public void setProductid(int productid) {
this.productid = productid;
}
public String getProductname() {
return productname;
}
public void setProductname(String productname) {
this.productname = productname;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
}
HTTP Status 500 - An exception occurred processing JSP page /WEB- INF/views/Product.jsp at line 64
type Exception report
message An exception occurred processing JSP page /WEB-INF/views/Product.jsp at line 64
description The server encountered an internal error that prevented it from fulfilling this request.
exception
org.apache.jasper.JasperException: An exception occurred processing JSP page /WEB-INF/views/Product.jsp at line 64
61: <tr>
62:
63: <td>Supplier :</td>
64: <td><spring:select path="supplierid"
65: items="${supplierlist}" itemValue="id" itemLabel="name" />
66: <td><spring:errors path="supplierid" cssClass="error" /></td>
67: </tr>
......
root cause org.springframework.beans.NotReadablePropertyException: Invalid property 'id' of bean class [com.niit.cakecuisinebe.model.Product]
答案 0 :(得分：0)
根据spring:select标记的documentation，属性itemValue应指向有效的bean属性。对于我在JSP上看到的内容，该代码块呈现Supplier信息......那么，您的Supplier类是否包含id实例属性（或bean属性）？如果没有，您应该将正确的属性放在itemValue标记属性...
但是，异常抱怨类Product没有id属性... ${supplierlist}表达式是否包含供应商对象或Product对象（您应该检查一下）...