Home >Java >JavaBase >Java implements uploading pictures to the server

Java implements uploading pictures to the server

王林Original: 2019-11-23 15:40:232915browse

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<FileItem> fileItemList = sfu.parseRequest(request);
		Iterator<FileItem> 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);
		    }
		    // <input type="file">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(&#39;.&#39;));
			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

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>更换头像</title>
</head>
<body>
         <formaction="UploadServlet.do" method="post"enctype="multipart/form-data">
                     本地目录：<inputtype="file" name="uploadFile">
           <img src="${image_path}" width="200" height="200">
                <inputtype="submit" value="上传头像"/>
   </form>
</body>
</html>

至此，图片上传数据库和本地服务器已经实现。

推荐教程：java入门教程

The above is the detailed content of Java implements uploading pictures to the server. For more information, please follow other related articles on the PHP Chinese website!

Java sql mysql html eclipse Session 数据库

Statement：

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Previous article：The file name is garbled when java downloads the fileNext article：The file name is garbled when java downloads the file

See more

Java implements uploading pictures to the server

Related articles