网站常用功能代码Java

1. 登录功能

//登录页面
<form action="login.jsp" method="post">
<label>用户名：</label><input type="text" name="username"><br>
<label>密码：</label><input type="password" name="password"><br>
<input type="submit" value="登录">
</form>

//登录处理
String username = request.getParameter("username");
String password = request.getParameter("password");
if(username.equals("admin") && password.equals("123456")){
session.setAttribute("username", username);
response.sendRedirect("home.jsp");
}else{
response.sendRedirect("login.jsp?error=1");
}

2. 注册功能

//注册页面
<form action="register.jsp" method="post">
<label>用户名：</label><input type="text" name="username"><br>
<label>密码：</label><input type="password" name="password"><br>
<label>确认密码：</label><input type="password" name="confirmPassword"><br>
<input type="submit" value="注册">
</form>

//注册处理
String username = request.getParameter("username");
String password = request.getParameter("password");
String confirmPassword = request.getParameter("confirmPassword");
if(password.equals(confirmPassword)){
//保存用户信息到数据库
response.sendRedirect("login.jsp");
}else{
response.sendRedirect("register.jsp?error=1");
}

3. 图片上传功能

//上传页面
<form action="upload.jsp" method="post" enctype="multipart/form-data">
<label>选择文件：</label><input type="file" name="file"><br>
<input type="submit" value="上传">
</form>

//上传处理
String savePath = "D:/uploads/"; //保存路径
String fileName = file.getOriginalFilename(); //获取文件名
File saveFile = new File(savePath + fileName);
file.transferTo(saveFile); //保存文件

4. 邮件发送功能

//邮件发送
String to = "recipient@example.com"; //收件人邮箱地址
String subject = "邮件主题"; //邮件主题
String content = "邮件内容"; //邮件内容
MailUtil.sendMail(to, subject, content); //发送邮件

5. 分页功能

//分页查询
int pageSize = 10; //每页显示条数
int currentPage = Integer.parseInt(request.getParameter("currentPage")); //当前页码
int totalCount = userDao.getTotalCount(); //记录总数
int totalPage = (int) Math.ceil(totalCount / (double)pageSize); //总页数
List<User> userList = userDao.getUserList(currentPage, pageSize); //查询指定页码的用户列表
request.setAttribute("userList", userList);
request.setAttribute("currentPage", currentPage);
request.setAttribute("totalPage", totalPage);

//分页显示
<ul>
<% for(User user : userList){ %>
<li><%= user.getUsername() %></li>
<% } %>
</ul>
<% if(currentPage > 1){ %>
<a href="?currentPage=<%= currentPage - 1 %>">上一页</a>
<% } %>
<% if(currentPage < totalPage){ %>
<a href="?currentPage=<%= currentPage + 1 %>">下一页</a>
<% } %>