请老师帮忙看一下，点击编辑id传不过去
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.imooc.canvas.global.GlobalController.service(GlobalController.java:57)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at com.imooc.canvas.global.EncodingFilter.doFilter(EncodingFilter.java:24)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:493)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:650)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:800)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:806)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1498)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NumberFormatException: For input string: ""
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
at java.lang.Integer.parseInt(Integer.java:592)
at java.lang.Integer.parseInt(Integer.java:615)
at com.imooc.canvas.controller.CanvasController.builder(CanvasController.java:78)
at com.imooc.canvas.controller.CanvasController.edit(CanvasController.java:62)
... 30 more
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<html>
<head>
<meta charset="UTF-8">
<title>油画列表</title>
<link rel="stylesheet" href="/css/index.css">
<link rel="stylesheet" href="/css/bootstrap.min.css">
</head>
<body>
<header>
<div class="container">
<nav>
<a href="#" >分类一</a>
</nav>
<nav>
<a href="#" >分类</a>
</nav>
<nav>
<a href="#">登录</a>
<a href="#" onclick="alert('功能暂未开放');">注册</a>
</nav>
</div>
</header>
<section class="banner">
<div class="container">
<div>
<h1>油画</h1>
<p>油画列表</p>
</div>
</div>
</section>
<section class="main">
<div class="container">
<table class="table table-striped">
<thead>
<tr>
<th>名称</th>
<th>分类</th>
<th>价格</th>
<th>创建时间</th>
<th>最后修改时间</th>
<th>描述</th>
<th>编辑</th>
<th>删除</th>
</tr>
</thead>
<tbody>
<c:forEach items="${list}" var="canvas">
<tr>
<td>${canvas.name}</td>
<td>${canvas.category.name}</td>
<td>￥<fmt:formatNumber type="currency" pattern="#,#00.00#" value="${canvas.price}"/></td>
<td><fmt:formatDate pattern="yyyy-MM-dd HH:mm:ss" value="${canvas.createTime}"/></td>
<td><fmt:formatDate pattern="yyyy-MM-dd HH:mm:ss" value="${canvas.updateTime}"/></td>
<td>${canvas.description}</td>
<td><a href="/admin/Canvas/toEdit.do?id=${canvas.id}">编辑</a></td>
<td><a href="#">删除</a>
</tr>
</c:forEach>
</tbody>
</table>
</div>
</section>
<section class="page">
<div class="container">
<div id="fatie">
<a href="/admin/Canvas/toAdd.do"><button>新建</button></a>
</div>
</div>
</section>
<footer>
copy@慕课网
</footer>
</body>
</html>package com.imooc.canvas.controller;
import com.imooc.canvas.biz.CanvasBiz;
import com.imooc.canvas.biz.CategoryBiz;
import com.imooc.canvas.biz.Impl.CanvasBizImpl;
import com.imooc.canvas.biz.Impl.CategoryBizImpl;
import com.imooc.canvas.entity.Canvas;
import com.imooc.canvas.entity.Category;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileItemFactory;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.Date;
import java.util.List;
public class CanvasController {
private CanvasBiz canvasBiz = new CanvasBizImpl();
private CategoryBiz categoryBiz = new CategoryBizImpl();
// /admin/Canvas/list.do
public void list(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
List<Canvas> list = canvasBiz.getAll();
request.setAttribute("list",list);
request.getRequestDispatcher("/WEB-INF/pages/admin/canvas_list.jsp").forward(request,response);
}
// /admin/Canvas/toAdd.do
public void toAdd(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
List<Category> list = categoryBiz.getRoot();
request.setAttribute("list",list);
request.getRequestDispatcher("/WEB-INF/pages/admin/canvas_add.jsp").forward(request,response);
}
// /admin/Canvas/add.do
public void add(HttpServletRequest request,HttpServletResponse response) throws Exception {
Canvas canvas = builder(request);
canvasBiz.add(canvas);
response.sendRedirect("list.do");
}
// /admin/Canvas/toEdit.do
public void toEdit(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
int id = Integer.parseInt(request.getParameter("id"));
Canvas canvas = canvasBiz.get(id);
request.setAttribute("canvas",canvas);
List<Category> list = categoryBiz.getRoot();
request.setAttribute("list",list);
request.getRequestDispatcher("/WEB-INF/pages/admin/canvas_edit.jsp").forward(request,response);
}
// /admin/Canvas/edit.do
public void edit(HttpServletRequest request,HttpServletResponse response) throws Exception {
Canvas canvas = builder(request);
canvasBiz.edit(canvas);
response.sendRedirect("list.do");
}
private Canvas builder(HttpServletRequest request) throws FileUploadException, UnsupportedEncodingException {
Canvas canvas = new Canvas();
FileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
upload.setHeaderEncoding("UTF-8");
List<FileItem> list = upload.parseRequest(request);
for (FileItem item:list){
//判断是表单项还是文件上传项
if(item.isFormField()){
//表单项
if (item.getFieldName().equals("id")){
canvas.setId(Integer.parseInt(item.getString("UTF-8")));
}
if (item.getFieldName().equals("name")){
canvas.setName(item.getString("UTF-8"));
}
if (item.getFieldName().equals("categoryId")){
canvas.setCategoryId(Integer.parseInt(item.getString("UTF-8")));
}
if(item.getFieldName().equals("price")){
canvas.setPrice(Integer.parseInt(item.getString("UTF-8")));
}
if (item.getFieldName().equals("imagePath")&&canvas.getImagePath()==null){
canvas.setImagePath(item.getString("UTF-8"));
}
if (item.getFieldName().equals("description")){
canvas.setDescription(item.getString("UTF-8"));
}
}else {
//文件上传项
if (item.getFieldName().equals("imagePath")){
if (item.getSize()<=100) continue;
String rootPath = request.getServletContext().getRealPath("/");
String path = item.getName();
String type = ".jpg";
if (path.indexOf(".")!=-1){
type = path.substring(path.lastIndexOf("."));
}
path = "/download/images/"+System.currentTimeMillis();
try {
item.write(new File(rootPath+path));
} catch (Exception e) {
e.printStackTrace();
}
canvas.setImagePath(path);
}
}
}
return canvas;
}
}<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<html>
<head>
<meta charset="UTF-8">
<title>编辑</title>
<link rel="stylesheet" href="/css/bootstrap.min.css">
<link rel="stylesheet" href="/css/add.css">
</head>
<body>
<nav class="navbar navbar-default">
<div class="container">
<div class="navbar-header">
<a class="navbar-brand" href="#">
慕课网油画管理
</a>
</div>
</div>
</nav>
<div class="container">
<div class="jumbotron">
<h1>Hello, admin!</h1>
<p>请小心的编辑油画记录</p>
</div>
<div class="page-header">
<h3><small>编辑</small></h3>
</div>
<form class="form-horizontal" action="/admin/Canvas/edit.do" method="post" enctype="multipart/form-data">
<input type="hidden" name="id" value="${canvas.id}">
<div class="form-group">
<label for="name" class="col-sm-2 control-label">名称 ：</label>
<div class="col-sm-8">
<input name="name" class="form-control" id="name" value="${canvas.name}">
</div>
</div>
<div class="form-group">
<label for="categoryId" class="col-sm-2 control-label">分类 ：</label>
<select id="categoryId" name="categoryId" class="col-sm-2 form-control" style="width: auto">
<c:forEach items="${list}" var="cat">
<option id="001" value="${cat.id}">${cat.name}</option>
</c:forEach>
</select>
</div>
<div class="form-group">
<label for="price" class="col-sm-2 control-label">价格 ：</label>
<div class="col-sm-8">
<input name="price" type="number" class="form-control" id="price" value="${canvas.price}">
</div>
</div>
<div class="form-group">
<label for="smallImg" class="col-sm-2 control-label">图片 ：</label>
<div class="col-sm-8">
<input id="smallImg" name="imagePath" class="file-loading"
type="file" multiple accept=".jpg,.jpeg,.png" data-min-file-count="1"
data-show-preview="true" value="${canvas.imagePath}">
</div>
</div>
<div class="form-group">
<label for="description" class="col-sm-2 control-label">描述 ：</label>
<div class="col-sm-8">
<input name="description" type="text" class="form-control" id="description" value="${canvas.description}">
</div>
</div>
<div class="form-group">
<div class="col-sm-offset-2 col-sm-10">
<button type="submit" class="btn btn-primary">保存</button>
</div>
</div>
</form>
</div>
<footer class="text-center" >
copy@imooc
</footer>
</body>
</html>正在回答
你好！从你贴出的图来看，代码出问题，还是因为id为0的canvas没有查询到。
在list方法中，将list集合的内容打印输出，看一下id值是什么
或者尝试在jsp中写Java脚本，也就是<% %>在此处获取list的值并遍历，查看一下id的值是多少，是否为0。
不知道你的Canvas类中id的类型是什么，int，Integer还是String。
如果还是有问题不好排查，建议把作业交上来整体看一下吧，在作业中可以说明一下这个问题没有解决。
祝学习愉快！
相似问题
登录后可查看更多问答，登录/注册
- 参与学习 人
- 提交作业 277 份
- 解答问题 4297 个
Java数据库开发的必备技能，从流行的MySQL数据库开始，到Java原生的数据库管理接口JDBC的使用，再到常用的数据持久化框架MyBatis，让你向Java工程师的目标又迈进了一步！
了解课程
恭喜解决一个难题，获得1积分~
来为老师/同学的回答评分吧
0 星