java上传图片到服务器并查看，了解一下？

@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);// image1478509873038.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();  
        }  
  
    }  
    }  
}  

@WebServlet("/persons.do")  
public class PersonServlet extends HttpServlet {  
  
    private static final long serialVersionUID = -800352785988546254L;  
  
    protected void service(HttpServletRequest request, HttpServletResponse response)  
        throws ServletException, IOException {  
    // 判断上传表单是否为multipart/form-data类型  
    Touxiang tx=null;  
      
    HttpSession session = request.getSession();  
    User user = (User) session.getAttribute("user"); // 在登录时将 User 对象放入了 会话  
    if(user!=null){  
        int myid=user.getId();  
        String SQL="SELECT id,image_path,old_name FROM t_touxiang WHERE user_id=?";  
        ResultSet rs=JdbcHelper.query(SQL,myid);  
        String uSQL="SELECT username,password FROM t_user WHERE id=?";  
        ResultSet urs=JdbcHelper.query(uSQL,myid);  
        System.out.println( "我的个人id是: " + myid);  
        final List<Touxiang> touxiang=new ArrayList<>();  
        try {  
        if(rs.next())  
        {  
            tx=new Touxiang();  
            tx.setId(rs.getInt(1));  
            tx.setImage_path(rs.getString(2));  
            tx.setOld_name(rs.getString(3));  
            touxiang.add(tx);  
        }  
        if(urs.next()){  
            user.setUsername(urs.getString(1));  
            user.setPassword(urs.getString(2));  
            user.setTouxiang(touxiang);  
        }  
          
        } catch (SQLException e) {  
        // TODO Auto-generated catch block  
        e.printStackTrace();  
        }  
         
        session.setAttribute("user", user);  
        System.out.println( "我的id: " + myid);  
        response.sendRedirect( request.getContextPath() + "/person.html");  
    }  
    }  
}