Jsp+Mysql+Jdbc+Servlet适合初学者的登陆查询的小项目（完整版）

package com.zhuce.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.zhuce.entity.Admin; import com.zhuce.entity.Msg; /** * @author weixin:zfldiv1101 */ public class AdminDao { public List<Msg> getAllMsg(String schoolname, String zhuanyename) { List<Msg> list = new ArrayList<Msg>(); Connection conn = DbHelper.getConnection(); String sql = "select * from msg where 1=1 "; if (schoolname != null && !"".equals(schoolname)) { sql += " and schoolname like '%"+schoolname+"%'"; } if(zhuanyename != null && !"".equals(zhuanyename)) { sql += " and zhuanyename like '%"+zhuanyename+"%'"; } try { PreparedStatement pst = conn.prepareStatement(sql); ResultSet rst = pst.executeQuery(); while (rst.next()) { Msg admin = new Msg(); admin.setId(rst.getInt("id")); admin.setSchoolname(rst.getString("schoolname")); admin.setZhuanyename(rst.getString("zhuanyename")); list.add(admin); } rst.close(); pst.close(); } catch (SQLException e) { e.printStackTrace(); } return list; } public List<Admin> getAllAdmin() { List<Admin> list = new ArrayList<Admin>(); Connection conn = DbHelper.getConnection(); String sql = "select * from admina "; try { PreparedStatement pst = conn.prepareStatement(sql); ResultSet rst = pst.executeQuery(); while (rst.next()) { Admin admin = new Admin(); admin.setId(rst.getInt("id")); admin.setUsername(rst.getString("username")); admin.setUserpwd(rst.getString("userpwd")); list.add(admin); } rst.close(); pst.close(); } catch (SQLException e) { e.printStackTrace(); } return list; } public boolean addAdmin(Admin admin) { String sql = "INSERT INTO `admina`(`id`,`username`,`userpwd`) VALUES (?,?,?)"; Connection conn = DbHelper.getConnection(); try { PreparedStatement pst = conn.prepareStatement(sql); pst.setInt(1, admin.getId()); pst.setString(2, admin.getUsername()); pst.setString(3, admin.getUserpwd()); int count = pst.executeUpdate(); pst.close(); return count > 0 ? true : false; } catch (SQLException e) { e.printStackTrace(); } return false; } public boolean updateAdmin(Admin admin) { String sql = "UPDATE `admina` SET `username`=?,`userpwd`=? WHERE `id` = ?"; Connection conn = DbHelper.getConnection(); try { PreparedStatement pst = conn.prepareStatement(sql); pst.setString(1, admin.getUsername()); pst.setString(2, admin.getUserpwd()); pst.setInt(3, admin.getId()); int count = pst.executeUpdate(); pst.close(); return count > 0 ? true : false; } catch (SQLException e) { e.printStackTrace(); } return false; } public boolean deleteAdmin(int id) { // ɾ�� String sql = "delete from admina where id = ?"; Connection conn = DbHelper.getConnection(); try { PreparedStatement pst = conn.prepareStatement(sql); pst.setInt(1, id); int count = pst.executeUpdate(); pst.close(); return count > 0 ? true : false; } catch (SQLException e) { e.printStackTrace(); } return false; } public Admin selectAdminById(int id) { Connection conn = DbHelper.getConnection(); String sql = "select * from admina where id = " + id; Admin admin = null; try { PreparedStatement pst = conn.prepareStatement(sql); ResultSet rst = pst.executeQuery(); while (rst.next()) { admin = new Admin(); admin.setId(rst.getInt("id")); admin.setUsername(rst.getString("username")); admin.setUserpwd(rst.getString("userpwd")); } rst.close(); pst.close(); } catch (SQLException e) { e.printStackTrace(); } return admin; } public Admin selectAdminByUsernameAndPwd(String uname,String pwd) { Connection conn = DbHelper.getConnection(); String sql = "select * from admina where username = '" + uname + "' and userpwd = '" + pwd + "'"; Admin admin = null; try { PreparedStatement pst = conn.prepareStatement(sql); ResultSet rst = pst.executeQuery(); while (rst.next()) { admin = new Admin(); admin.setId(rst.getInt("id")); admin.setUsername(rst.getString("username")); admin.setUserpwd(rst.getString("userpwd")); } rst.close(); pst.close(); } catch (SQLException e) { e.printStackTrace(); } return admin; } }