jsp+servlet+mysql实现简单登陆注册

package com.db; import com.model.Usedata; import javax.servlet.RequestDispatcher; import javax.xml.crypto.Data; import java.sql.*; import java.util.ArrayList; public class Database { Connection conn=null; public Database() throws ClassNotFoundException, SQLException { Class.forName("com.mysql.cj.jdbc.Driver"); this.conn= DriverManager.getConnection("jdbc:mysql://localhost:3306/test_1?serverTimezone=GMT","root", "13967434499" ); //System.out.println("连接成功！"); } public void showConnection(){ if (conn==null){ System.out.println("连接失败"); }else{ System.out.println("连接成功！"); } } //关闭连接 public void close()throws SQLException{ conn.close(); } //在admin表里面插入数据 public void insert(String name,String pwd) throws SQLException { PreparedStatement prep = conn.prepareStatement("insert into test_1.admin value (null ,?,?)"); prep.setString(1, name); prep.setString(2, pwd); prep.execute(); } //查询数据 public ArrayList<Usedata>getAlluser() throws SQLException { ArrayList<Usedata> uselist = new ArrayList<Usedata>(); PreparedStatement prep=conn.prepareStatement("select * from test_1.admin"); prep.execute(); ResultSet resultSet=prep.executeQuery(); while (resultSet.next()){ int myid=resultSet.getInt("id"); String myname = resultSet.getString("name"); String mypwd=resultSet.getString("password"); uselist.add(new Usedata(myid,myname,mypwd)); } return uselist; } //在表里查询数据 public Usedata getuser(int id) throws SQLException { PreparedStatement prep=conn.prepareStatement("select * from test_1.admin where id=?"); prep.setInt(1, id); prep.execute(); ResultSet resultSet=prep.executeQuery(); if (resultSet.next()){ int myid=resultSet.getInt("id"); String myname = resultSet.getString("name"); String mypwd=resultSet.getString("password"); return new Usedata(myid,myname,mypwd); } return null; } public Usedata login(int id,String pwd) throws SQLException { PreparedStatement prep=conn.prepareStatement("select test_1.admin.password from test_1.admin where id=?"); prep.setInt(1, id); prep.execute(); ResultSet resultSet=prep.executeQuery(); if (resultSet.next()) { String mypwd= resultSet.getString("password"); if (pwd.equals(mypwd)) { return getuser(id); } else return null; } else return null; } }