JAVA web数据库登录界面
package com.jaovo.msg.dao; import java.util.List; import com.jaovo.msg.model.User; public interface IUserDao { public void add(User user); public void delete(int id); public void update(User user); public User load(int id); public User load(String username); public List<User> load(); }
package com.jaovo.msg.dao; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.util.ArrayList; import java.util.List; import com.jaovo.msg.Util.DBUtil; import com.jaovo.msg.Util.UserException; import com.jaovo.msg.model.User; //import sun.net.www.content.text.plain; public class UserDaoImpl implements IUserDao { @Override public void add(User user) { //获得链接对象 Connection connection = DBUtil.getConnection(); //准备sql语句 String sql = "select count(*) from t_user where username = ?"; //创建语句传输对象 PreparedStatement preparedStatement = null; ResultSet resultSet = null; try { preparedStatement = connection.prepareStatement(sql); preparedStatement.setString(1, user.getUsername()); //接收结果集 resultSet = preparedStatement.executeQuery(); //遍历结果集 while(resultSet.next()) { if (resultSet.getInt(1) > 0) { throw new UserException("用户已存在") ; } } sql = "insert into t_user(username,password,nickname) value (?,?,?)"; preparedStatement = connection.prepareStatement(sql); preparedStatement.setString(1, user.getUsername()); preparedStatement.setString(2, user.getPassword()); preparedStatement.setString(3, user.getNickname()); preparedStatement.executeUpdate(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); }finally { //关闭资源 DBUtil.close(resultSet); DBUtil.close(preparedStatement); DBUtil.close(connection); } } @Override public void delete(int id) { Connection connection = DBUtil.getConnection(); String sql = "delete from t_user where id = ?"; PreparedStatement preparedStatement = null; try { preparedStatement = connection.prepareStatement(sql); preparedStatement.setInt(1, id); preparedStatement.executeUpdate(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); }finally { DBUtil.close(preparedStatement); DBUtil.close(connection); } } @Override public void update(User user) { Connection connection = DBUtil.getConnection(); //准备sql语句 String sql = "update t_user set password = ? , nickname=? where id = ?"; //创建语句传输对象 PreparedStatement preparedStatement = null; try { preparedStatement = connection.prepareStatement(sql); preparedStatement.setString(1, user.getPassword()); preparedStatement.setString(2, user.getNickname()); preparedStatement.setInt(3, user.getId()); preparedStatement.executeUpdate(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); }finally { DBUtil.close(preparedStatement); DBUtil.close(connection); } } @Override public User load(int id) { Connection connection = DBUtil.getConnection(); //准备sql语句 String sql = "select * from t_user where id = ?"; //创建语句传输对象 PreparedStatement preparedStatement = null; ResultSet resultSet = null; User user = null; try { preparedStatement = connection.prepareStatement(sql); preparedStatement.setInt(1, id); resultSet = preparedStatement.executeQuery(); while(resultSet.next()) { user = new User(); user.setId(id); user.setUsername(resultSet.getString("username")); user.setPassword(resultSet.getString("password")); user.setNickname(resultSet.getString("nickname")); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); }finally { DBUtil.close(resultSet); DBUtil.close(preparedStatement); DBUtil.close(connection); } return user; } @Override public User load(String username) { // TODO Auto-generated method stub return null; } @Override public List<User> load() { Connection connection = DBUtil.getConnection(); //准备sql语句 String sql = "select * from t_user "; //创建语句传输对象 PreparedStatement preparedStatement = null; ResultSet resultSet = null; //集合中只能放入user对象 List<User> users = new ArrayList<User>(); User user = null; try { preparedStatement = connection.prepareStatement(sql); resultSet = preparedStatement.executeQuery(); while(resultSet.next()) { user = new User(); user.setId(resultSet.getInt("id")); user.setUsername(resultSet.getString("username")); user.setPassword(resultSet.getString("password")); user.setNickname(resultSet.getString("nickname")); users.add(user); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); }finally { DBUtil.close(resultSet); DBUtil.close(preparedStatement); DBUtil.close(connection); } return users; } }
package com.jaovo.msg.model; public class User { private int id; private String username; private String nickname; private String password; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getNickname() { return nickname; } public void setNickname(String nickname) { this.nickname = nickname; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } }
package com.jaovo.msg.Util; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; public class DBUtil { public static Connection getConnection() { try { //1 加载驱动 Class.forName("com.mysql.jdbc.Driver").newInstance(); } catch (InstantiationException | IllegalAccessException | ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } String user = "root"; String password = "root"; String url = "jdbc:mysql://localhost:3306/jaovo_msg"; Connection connection = null; try { //2 创建链接对象connection connection = DriverManager.getConnection(url,user,password); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } return connection; } //关闭资源的方法 public static void close(Connection connection ) { try { if (connection != null) { connection.close(); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public static void close(PreparedStatement preparedStatement ) { try { if (preparedStatement != null) { preparedStatement.close(); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public static void close(ResultSet resultSet ) { try { if (resultSet != null) { resultSet.close(); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }
package com.jaovo.msg.Util; public class UserException extends RuntimeException{ public UserException() { super(); // TODO Auto-generated constructor stub } public UserException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) { super(message, cause, enableSuppression, writableStackTrace); // TODO Auto-generated constructor stub } public UserException(String message, Throwable cause) { super(message, cause); // TODO Auto-generated constructor stub } public UserException(String message) { super(message); // TODO Auto-generated constructor stub } public UserException(Throwable cause) { super(cause); // TODO Auto-generated constructor stub } }
<%@page import="com.jaovo.msg.Util.UserException"%> <%@page import="com.jaovo.msg.dao.UserDaoImpl"%> <%@page import="com.jaovo.msg.model.User"%> <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <% //接收客户端传递过来的参数 String username = request.getParameter("username"); String password = request.getParameter("password"); String nickname = request.getParameter("nickname"); if(username == null || "".equals(username.trim())){ request.setAttribute("error", "用户名不能为空"); %> <jsp:forward page="addInput.jsp"></jsp:forward> <% } User user = new User(); user.setUsername(username); user.setPassword(password); user.setNickname(nickname); UserDaoImpl userDao = new UserDaoImpl(); try{ userDao.add(user); //重定向 response.sendRedirect("list.jsp"); %> <% }catch(UserException e){ %> <h2 style="color:red ; font-size:50px">发生错误 : <%=e.getMessage() %></h2> <% } %> </html>
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <title>用户添加页面</title> </head> <body> <%=request.getAttribute("error") %> <form action="add.jsp" method="get"> <table align="center" border="1" width="500"> <tr> <td>用户名称 : </td> <td> <input type="text" name="username" /> </td> </tr> <tr> <td>用户密码:</td> <td> <input type="password" name="password" /> </td> </tr> <tr> <td>用户昵称:</td> <td> <input type="text" name="nickname" /> </td> </tr> <tr align="center"> <td colspan="2"> <input type="submit" value="提交" /> <input type="reset" value="重置" /> </td> </tr> </table> </form> </body> </html>
实验结果截图:
错误原因分析:
对数据库练结合使用不熟练,不会对网页进行编写,从零开始有点难,需要付出时间和精力去熟练