package nhh.bean;
public class User { public User(){
} public User(int id, String username,String password){ this.id = id; this.username = username; this.password = password; } public User(String username,String password){ this.username = username; this.password = password; } private int id; private String username; 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 getPassword() { return password; } public void setPassword(String password) { this.password = password; } @Override public String toString() { return "User{" + "id=" + id + ", username='" + username + '\'' + ", password='" + password + '\'' + '}'; }}
用户写方法 package nhh.dao;
import nhh.bean.User; import nhh.util.DBUtil;
import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.util.ArrayList; import java.util.List;
public class UserDao { public List findAll() { Connection connection = null; List userList = new ArrayList<>(); PreparedStatement statement = null; ResultSet resultSet = null;
//3.写sql语句 //4.获得statement对象 try { connection = DBUtil.getConnection(); String sql = "select *from tb_user "; statement = connection.prepareStatement(sql); resultSet = statement.executeQuery(); while (resultSet.next()) { User user = new User(); user.setId(resultSet.getInt(1)); user.setUsername(resultSet.getString(2)); user.setPassword(resultSet.getString(3)); userList.add(user); } } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException throwables) { throwables.printStackTrace(); } finally { try { DBUtil.closeAll(resultSet, statement, connection); } catch (SQLException throwables) { throwables.printStackTrace(); } } return userList; } public void deleteById(int id){ Connection connection = null; PreparedStatement statement=null; try { connection =DBUtil.getConnection(); String sql="delete from tb_user where id=?"; statement=connection.prepareStatement(sql); statement.setInt(1,id); statement.executeUpdate(); } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException throwables) { throwables.printStackTrace(); }finally { try { DBUtil.closeAll(null,statement,connection); } catch (SQLException throwables) { throwables.printStackTrace(); } } }}
链接数据库
package nhh.util;
import java.sql.*;
public class DBUtil { public static Connection getConnection() throws ClassNotFoundException, SQLException { Class.forName(“com.mysql.jdbc.Driver”); //2.创建链接 Connection connection = DriverManager.getConnection(“jdbc:mysql://localhost:3306/wzsxy”,“root”,“123456”); return connection; }
public static void closeAll(ResultSet resultSet, Statement statement, Connection connection) throws SQLException { if(resultSet!=null){ resultSet.close(); } if(statement!=null){ resultSet.close(); } if(connection!=null){ resultSet.close(); } }}
package nhh;
import nhh.bean.User; import nhh.dao.UserDao;
import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; import java.util.ArrayList; import java.util.List;
public class LoginServlet extends HttpServlet {
@Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { UserDao userDao=new UserDao(); String username=req.getParameter("username"); String password=req.getParameter("password"); List<User> userList=new ArrayList<>(); System.out.println(username); userList=userDao.findAll(); int r=0; for(User user:userList){ if(user.getUsername().equals(username)&&user.getPassword().equals(password)){ resp.getWriter().write("yes"); r=1; } } if(r==0){ resp.getWriter().write("no"); } }}
总结：很充实很快乐，老师讲解的很仔细！
