文章目录

• 一、模式分析
• 二、架构设计
• 三、代码框架
• 四、数据库设置
• 五、核心代码
• • 1.User.java
  • 2.UserDAO.java
  • 3.LoginServlet.java
  • 4.RegServlet.java
  • 5.login.jsp
  • 6.register.jsp
  • 7.welcome.jsp
• 六、运行截图
• 七、资源下载与学习
• 联系作者

一、模式分析

二、架构设计

三、代码框架

四、数据库设置

五、核心代码

1.User.java

public class User {
	private String username;
	private String password;
	public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		this.username = username;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
	
}

2.UserDAO.java

public class UserDAO {
	public static final String DRIVER = "com.mysql.cj.jdbc.Driver";
	public static final String DBURL = "jdbc:mysql://localhost:3306/mydb?serverTimezone=UTC";//在这里将3306改为自己的数据库端口号
	public static final String DBUSER = "root";//在这里更改为自己数据库的用户名
	public static final String DBPASS = "123456";//在这里更改为自己数据库的密码
	private Connection conn = null;
	private PreparedStatement pStat = null;
	private ResultSet rs = null;

	public Connection getConnectionn() {
		try {
			Class.forName(DRIVER);
			return DriverManager.getConnection(DBURL, DBUSER, DBPASS);
		} catch (Exception e) {
			return null;
		}
	}

	public void close() {
		try {
			if (rs != null)
				rs.close();
			if (pStat != null)
				pStat.close();
			if (conn != null)
				conn.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
	} // end close

	public boolean isUsernameExists(String username) {
		conn = getConnectionn();
		try {
			pStat = conn.prepareStatement("select * from users where username=?");
			pStat.setString(1, username);
			rs = pStat.executeQuery();
			if (rs.next())
				return true;
			else
				return false;
		} catch (Exception e) {
			return false;
		} finally {
			close();
		}
	} // end isUsernameExists

	public boolean addUser(User user) {
		conn = getConnectionn();
		try {
			pStat = conn.prepareStatement("insert into users values(null,?,?)");
			pStat.setString(1, user.getUsername());
			pStat.setString(2, user.getPassword());
			int cnt = pStat.executeUpdate();
			if (cnt > 0)
				return true;
			else
				return false;
		} catch (Exception e) {
			return false;
		} finally {
			close();
		}
	} // end add

	public boolean findUser(String username, String password) {
		conn = getConnectionn();
		try {
			pStat = conn.prepareStatement("select * from users where username=? and password=?");
			pStat.setString(1, username);
			pStat.setString(2, password);
			rs = pStat.executeQuery();
			if (rs.next())
				return true;
			else
				return false;
		} catch (Exception e) {
			return false;
		} finally {
			close();
		}
	} // end findUse
}//end class

3.LoginServlet.java

// TODO Auto-generated method stub
		String username = request.getParameter("username");
		String password = request.getParameter("password");
		UserDAO userdao = new UserDAO();
		boolean flag = userdao.findUser(username, password);
		if (flag) {
			request.getSession().setAttribute("username", username);
			response.sendRedirect("welcome.jsp");
		} else {
			request.getSession().setAttribute("err", "用户名或密码不正确！");
			response.sendRedirect("login.jsp");
		}

4.RegServlet.java

// TODO Auto-generated method stub
		String username = request.getParameter("username");
		String password = request.getParameter("password");
		User user = new User();
		user.setUsername(username);
		user.setPassword(password);
		UserDAO userdao = new UserDAO();
		if (userdao.isUsernameExists(username)) {
			request.getSession().setAttribute("err", "用户名已存在");
			response.sendRedirect("register.jsp");
		} else {
			boolean flag = userdao.addUser(user);
			if (flag) {
				request.getSession().setAttribute("username", username);
				response.sendRedirect("welcome.jsp");
			} else {
				request.getSession().setAttribute("err", "注册失败");
				response.sendRedirect("register.jsp");
			}
		}

5.login.jsp

<%
String errMsg=(String)session.getAttribute("err"); 
if( errMsg!=null ) { %>
<div style="color:red;"><%=errMsg %></div>
<% session.removeAttribute("err");
} %>
<form action="LoginServlet"> 
用户名<input type="text" name="username"><br/>
密码<input type="password" name="password"><br/>
<input type="submit" value="登录">
<input type="reset" value="重填">
</form>

6.register.jsp

<%
String errMsg=(String)session.getAttribute("err"); 
if( errMsg!=null ) { %>
<div style="color:red;"><%=errMsg %></div>
<% session.removeAttribute("err");
}%>
<form action="RegServlet">
用户名<input type="text" name="username"><br/>
密码<input type="password" name="password"><br/>
<input type="submit" value="注册">
<input type="reset" value="重填">
</form>

7.welcome.jsp

<%
String username=(String)session.getAttribute("username");
if(username!=null&&!username.isEmpty()) { %>
你已经登录，欢迎<%=session.getAttribute("username") %>
<% } 
else{
out.print("你还没有登录，3秒后自动跳往登录页面");
response.setHeader("refresh", "3;url=login.jsp");
} %>

六、运行截图

七、资源下载与学习

CSDN下载：JSP+Servlet+JavaBean模式实现登录注册

联系作者

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