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Java implements uploading pictures to the server

王林
王林 Original
2019-11-23 15:40:23 2760browse

Java implements uploading pictures to the server

实现的思路:

工具:MySQL,eclipse

首先,在MySQL中创建了两个表,一个t_user表,用来存放用户名,密码等个人信息,一个t_touxiang表,用来存放上传的图片在服务器中的存放路径,以及图片名字和用户ID,T_touxiang表中的用户ID对应了t_user中的id。

t_user表SQL:

DROP TABLE IF EXISTS `t_user`; CREATE TABLE `t_user` ( `id` int(10) NOT NULL AUTO_INCREMENT, `username` varchar(20) NOT NULL, `password` varchar(255) NOT NULL, PRIMARY KEY (`id`), UNIQUE KEY `username` (`username`) ) ENGINE=InnoDB AUTO_INCREMENT=22 DEFAULT CHARSET=utf8;

T_touxiang表SQL:

DROP TABLE IF EXISTS `t_touxiang`; CREATE TABLE `t_touxiang` ( `id` int(10) NOT NULL AUTO_INCREMENT, `image_path` varchar(255) DEFAULT NULL, `user_id` int(11) DEFAULT NULL, `old_name` varchar(255) DEFAULT NULL, PRIMARY KEY (`id`), KEY `img_user` (`user_id`), CONSTRAINT `img_user` FOREIGN KEY (`user_id`) REFERENCES `t_user` (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8;

首先,写一个UploadServlet.java,用来处理图片文件的上传,并将图片路径,图片名称等信息存放到t_touxiang数据表中,代码如下:

@WebServlet("/UploadServlet.do") public class UploadServlet extends HttpServlet { private static final long serialVersionUID = 1L; protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 判断上传表单是否为multipart/form-data类型 HttpSession session = request.getSession(); User user = (User) session.getAttribute("user"); // 在登录时将 User 对象放入了会话中 if (ServletFileUpload.isMultipartContent(request)) { try { // 1. 创建DiskFileItemFactory对象,设置缓冲区大小和临时文件目录 DiskFileItemFactory factory = new DiskFileItemFactory(); // System.out.println(System.getProperty("java.io.tmpdir"));//默认临时文件夹 // 2. 创建ServletFileUpload对象,并设置上传文件的大小限制。 ServletFileUpload sfu = new ServletFileUpload(factory); sfu.setSizeMax(10 * 1024 * 1024);// 以byte为单位 不能超过10M 1024byte = // 1kb 1024kb=1M 1024M = 1G sfu.setHeaderEncoding("utf-8"); // 3. // 调用ServletFileUpload.parseRequest方法解析request对象,得到一个保存了所有上传内容的List对象。 @SuppressWarnings("unchecked") List fileItemList = sfu.parseRequest(request); Iterator fileItems = fileItemList.iterator(); // 4. 遍历list,每迭代一个FileItem对象,调用其isFormField方法判断是否是上传文件 while (fileItems.hasNext()) { FileItem fileItem = fileItems.next(); // 普通表单元素 if (fileItem.isFormField()) { String name = fileItem.getFieldName();// name属性值 String value = fileItem.getString("utf-8");// name对应的value值 System.out.println(name + " = " + value); } // 的上传文件的元素 else { String fileName = fileItem.getName();// 文件名称 System.out.println("原文件名:" + fileName);// Koala.jpg String suffix = fileName.substring(fileName.lastIndexOf('.')); System.out.println("扩展名:" + suffix);// .jpg // 新文件名(唯一) String newFileName = new Date().getTime() + suffix; System.out.println("新文件名:" + newFileName);// image\1478509873038.jpg // 5. 调用FileItem的write()方法,写入文件 File file = new File("D:/lindaProjects/mySpace/wendao/WebContent/touxiang/" + newFileName); System.out.println(file.getAbsolutePath()); fileItem.write(file); // 6. 调用FileItem的delete()方法,删除临时文件 fileItem.delete(); /* * 存储到数据库时注意 1.保存源文件名称 Koala.jpg 2.保存相对路径 * image/1478509873038.jpg * */ if (user != null) { int myid = user.getId(); String SQL = "INSERT INTO t_touxiang(image_path,user_id,old_name)VALUES(?,?,?)"; int rows = JdbcHelper.insert(SQL, false, "touxiang/" + newFileName, myid, fileName); if (rows > 0) { session.setAttribute("image_name", fileName); session.setAttribute("image_path", "touxiang/" + newFileName); response.sendRedirect(request.getContextPath() + "/upImage.html"); } else { } } else { session.setAttribute("loginFail", "请登录"); response.sendRedirect(request.getContextPath() + "/login.html"); } } } } catch (FileUploadException e) { e.printStackTrace(); } catch (Exception e) { e.printStackTrace(); } } } }

在完成图片上传并写入数据库的同时,将图片路径通过session的方式发送到HTML界面

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本地目录:

至此,图片上传数据库和本地服务器已经实现。

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