Question

java程序网页页面中不能显示图片

@RequestMapping(value = "/allGoods")
public ModelAndView goods(HttpServletRequest request) {
User cur_user = (User)request.getSession().getAttribute("cur_user");
Integer userId = cur_user.getId();
List<Goods> goodsList = goodsService.getGoodsByUserId(userId);
List<GoodsExtend> goodsAndImage = new ArrayList<GoodsExtend>();
for (int i = 0; i < goodsList.size() ; i++) {
//将用户信息和image信息封装到GoodsExtend类中，传给前台
GoodsExtend goodsExtend = new GoodsExtend();
Goods goods = goodsList.get(i);
List<Image> images = imageService.getImagesByGoodsPrimaryKey(goods.getId());
goodsExtend.setGoods(goods);
goodsExtend.setImages(images);
goodsAndImage.add(i, goodsExtend);
}
ModelAndView mv = new ModelAndView();
mv.addObject("goodsAndImage",goodsAndImage);
mv.setViewName("/user/goods");
return mv;
}
}
为什么用数据库调用不了图片

Answer 1

使用一些已有的组件帮助我们实现这种上传功能。
常用的上传组件：
Apache 的 Commons FileUpload
JavaZoom的UploadBean
jspSmartUpload
以下，以FileUpload为例讲解
1、在jsp端
<form id="form1" name="form1" method="post" action="servlet/fileServlet" enctype="multipart/form-data">
要注意enctype="multipart/form-data"
然后只需要放置一个file控件，并执行submit操作即可
<input name="file" type="file" size="20" >
<input type="submit" name="submit" value="提交" >
2、web端
核心代码如下：
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("UTF-8");
DiskFileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
try {
List items = upload.parseRequest(request);
Iterator itr = items.iterator();
while (itr.hasNext()) {
FileItem item = (FileItem) itr.next();
if (item.isFormField()) {
System.out.println("表单参数名:" + item.getFieldName() + "，表单参数值:" + item.getString("UTF-8"));
} else {
if (item.getName() != null && !item.getName().equals("")) {
System.out.println("上传文件的大小:" + item.getSize());
System.out.println("上传文件的类型:" + item.getContentType());
System.out.println("上传文件的名称:" + item.getName());
File tempFile = new File(item.getName());
File file = new File(sc.getRealPath("/") + savePath, tempFile.getName());
item.write(file);
request.setAttribute("upload.message", "上传文件成功！");
}else{
request.setAttribute("upload.message", "没有选择上传文件！");
}
}
}
}catch(FileUploadException e){
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
request.setAttribute("upload.message", "上传文件失败！");
}
request.getRequestDispatcher("/uploadResult.jsp").forward(request, response);
}