web图片上传功能

//首先对请求进行解析，判断是不是一个上传文件的表单请求
boolean isMultipart = ServletFileUpload.isMultipartContent(request);
if (isMultipart) {
	try {
		//1.实例化缓冲区
		DiskFileItemFactory factory = new DiskFileItemFactory();
		//2.获取对文件操作的对象
		ServletFileUpload upload = new ServletFileUpload(factory);
		//设置上传数据时的默认字符集
		upload.setHeaderEncoding("UTF-8");
		//设置上传文件大小
		upload.setSizeMax(10 * 1024 * 1024);

		//获取所有表单项
		List fileItems = upload.parseRequest(request);
		
		Iterator iter = fileItems.iterator();

		// 依次处理每个表单域
		while (iter.hasNext()) {
			FileItem item = (FileItem) iter.next();

			if (!item.isFormField()) {
				// 如果item是上传文件
				// 获得文件名及路径
				String fileName = item.getName();

				if (fileName != null && fileName.indexOf(".") != -1) {
					//设置上传文件的新文件名，UUID
					String fileNewName = UUID.randomUUID().toString().replace("-","")
							+ "."
							+ fileName.substring(fileName.indexOf(".") + 1);
					//把文件保存在服务器上本web应用目录下
					File fullFile = new File(getServletContext()  
							.getRealPath("/images/photo/"), fileNewName);
					
					//写文件
					item.write(fullFile);
					
				
					
					request.setAttribute("imagePath", "images/photo/"+fileNewName);
					request.getRequestDispatcher("upload.jsp").forward(request, response);
			} else {
				}
				item.delete();
			}
		}
	} catch (Exception e) {
		e.printStackTrace();
	}
}

小结：form表单的enctype 属性必须是 multipart/form-data” 注意post请求