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<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('.'));
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。
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