选课系统javaweb增删改查（下）

我在学习Javaweb时，选用的学习模板将dao层与utils层揉在一起了，导致没有dao层，感觉逻辑不清晰，昨日与大佬的交流中（软工学科大佬🤭），仔细了解了到层的结构层次，这点我会在网上再进行学习改进。utils内大致是一样的，在测试时，就考虑到除了其中调用的sqlstring语句是不同的之外，基本相同（个别的utiils中有一两个链接jsp的方法用来遍历输出的）,我就直接复制的，当然这种方法会是工程的代码量加倍，本着简洁为主，这种方法不可取（我会进行优化学习的），我会想办法在日后的测试学习中整合为一个utils实现所有的调用（目前思考方向：选个判断的字段判断，调用sqlstring但是我还不知道选哪个字段可以串起系统）

utils包：

utils.java

package utils;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
//import Bean.information;
public class utils {
    private static Connection conn=null; 
    private static PreparedStatement ps=null;
     private static ResultSet rs=null;
    static {
             // 定义连接
         

        try {
            // 加载驱动
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/db6", "root", "132956");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public static List<HashMap<String, Object>> getMysqlData() {
        // 预执行加载
        PreparedStatement preparedStatement = null;
        // 结果集
        ResultSet resultSet = null;

        //准备的sql
        String sqlString = "select * from register";

        List<HashMap<String, Object>> list = new ArrayList<HashMap<String,Object>>();
        try {
            //预编译
            preparedStatement = conn.prepareStatement(sqlString);
            resultSet = preparedStatement.executeQuery();  //查询
            HashMap<String, Object> map = null;
            while (resultSet.next()) {    //遍历结果集
                map = new HashMap<String, Object>();
                map.put("name", resultSet.getString("name"));   //获取字段名称nickName的值，
                list.add(map);//将nickName的值添加到map中
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (resultSet != null) {
                    resultSet.close();
                }
                if (preparedStatement != null) {
                    preparedStatement.close();
                }
                if (conn != null) {
                    conn.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return list;
    }

    public  int update(String sql,Object[] objects){
        int a=0;
        try {
            
            //创建sql载体
            ps=conn.prepareStatement(sql);
            //给占位符赋值
            for(int i=0;i<objects.length;i++){
                ps.setObject(i+1, objects[i]);
            }
            //操作SQL语句
            a=ps.executeUpdate(); 
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return a;
    }
 public ResultSet query(String sql,Object[] objects){
        
        try {
            ps=conn.prepareStatement(sql);
            //给占位符赋值
            
            for(int i=0;i<objects.length;i++){
                ps.setObject(i+1, objects[i]);
            }
            rs=ps.executeQuery();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return rs;
    }
// public int setinformation(information to)
// {
//     try {
//        String sql="select * from register where id =?";
//         PreparedStatement ps=conn.prepareStatement(sql);
//        ResultSet k=ps.executeQuery(sql);
//        to.setId(k.getString(0));
//        to.setCode(k.getString(1));
//        to.setShenfen(k.getString(2));
//     } catch (SQLException e) {
//         e.printStackTrace();
//     }
//     return 0;
// }
 
 
}

utilskecheng.java

package utils;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import Bean.course;
//import Bean.information;
public class utilskecheng {
    private static Connection conn=null; 
    private static PreparedStatement ps=null;
     private static ResultSet rs=null;
    static {
             // 定义连接
         

        try {
            // 加载驱动
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/db6", "root", "132956");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public static List<HashMap<String, Object>> getMysqlData() {
        // 预执行加载
        PreparedStatement preparedStatement = null;
        // 结果集
        ResultSet resultSet = null;

        //准备的sql
        String sqlString = "select * from kecheng";

        List<HashMap<String, Object>> list = new ArrayList<HashMap<String,Object>>();
        try {
            //预编译
            preparedStatement = conn.prepareStatement(sqlString);
            resultSet = preparedStatement.executeQuery();  //查询
            HashMap<String, Object> map = null;
            while (resultSet.next()) {    //遍历结果集
                map = new HashMap<String, Object>();
                map.put("name", resultSet.getString("name"));   //获取字段名称nickName的值，
                list.add(map);//将nickName的值添加到map中
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (resultSet != null) {
                    resultSet.close();
                }
                if (preparedStatement != null) {
                    preparedStatement.close();
                }
                if (conn != null) {
                    conn.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return list;
    }

    public  int update(String sql,Object[] objects){
        int a=0;
        try {
            
            //创建sql载体
            ps=conn.prepareStatement(sql);
            //给占位符赋值
            for(int i=0;i<objects.length;i++){
                ps.setObject(i+1, objects[i]);
            }
            //操作SQL语句
            a=ps.executeUpdate(); 
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return a;
    }
 public ResultSet query(String sql,Object[] objects){
        
        try {
            ps=conn.prepareStatement(sql);
            //给占位符赋值
            
            for(int i=0;i<objects.length;i++){
                ps.setObject(i+1, objects[i]);
            }
            rs=ps.executeQuery();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return rs;
    }
// public int setinformation(information to)
// {
//     try {
//        String sql="select * from register where id =?";
//         PreparedStatement ps=conn.prepareStatement(sql);
//        ResultSet k=ps.executeQuery(sql);
//        to.setId(k.getString(0));
//        to.setCode(k.getString(1));
//        to.setShenfen(k.getString(2));
//     } catch (SQLException e) {
//         e.printStackTrace();
//     }
//     return 0;
// }
 
 public void select4(String sql,ArrayList<course> arr)
 {
     
     try {
         //创建sql载体
         ps=conn.prepareStatement(sql);
         ResultSet rs  = ps.executeQuery();
         System.out.println(rs);
         while(rs.next()) {
         course B = new course();
         B.setId(rs.getString(1));
         B.setName(rs.getString(2));
         B.setStunum(rs.getString(3));
         B.setS(rs.getString(4));
         arr.add(B);
         
         System.out.println(arr.get(0));
         }
     } catch (SQLException e) {
         e.printStackTrace();
     }
 }
 
 public void select5(String sql,String name,ArrayList<course> arr)
 {
     
     try {
         //创建sql载体
//         String sql="select * from kecheng where name=?";
         ps=conn.prepareStatement(sql);
//         ResultSet rs  = ps.executeQuery(name);
         Object[] objs1={name};
         utilskecheng to=new utilskecheng();
          ResultSet rs=to.query(sql, objs1);
         while(rs.next()) {
         course B = new course();
         B.setId(rs.getString(1));
         B.setName(rs.getString(2));
         B.setStunum(rs.getString(3));
         B.setS(rs.getString(4));
         arr.add(B);
         }
     } catch (SQLException e) {
         e.printStackTrace();
     }
 }
}

utilss.java

package utils;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
//import Bean.information;
public class utilss {
    private static Connection conn=null; 
    private static PreparedStatement ps=null;
     private static ResultSet rs=null;
    static {
             // 定义连接
         

        try {
            // 加载驱动
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/db6", "root", "132956");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public static List<HashMap<String, Object>> getMysqlData() {
        // 预执行加载
        PreparedStatement preparedStatement = null;
        // 结果集
        ResultSet resultSet = null;

        //准备的sql
        String sqlString = "select * from student";

        List<HashMap<String, Object>> list = new ArrayList<HashMap<String,Object>>();
        try {
            //预编译
            preparedStatement = conn.prepareStatement(sqlString);
            resultSet = preparedStatement.executeQuery();  //查询
            HashMap<String, Object> map = null;
            while (resultSet.next()) {    //遍历结果集
                map = new HashMap<String, Object>();
                map.put("name", resultSet.getString("name"));   //获取字段名称nickName的值，
                list.add(map);//将nickName的值添加到map中
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (resultSet != null) {
                    resultSet.close();
                }
                if (preparedStatement != null) {
                    preparedStatement.close();
                }
                if (conn != null) {
                    conn.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return list;
    }

    public  int update(String sql,Object[] objects){
        int a=0;
        try {
            
            //创建sql载体
            ps=conn.prepareStatement(sql);
            //给占位符赋值
            for(int i=0;i<objects.length;i++){
                ps.setObject(i+1, objects[i]);
            }
            //操作SQL语句
            a=ps.executeUpdate(); 
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return a;
    }
 public ResultSet query(String sql,Object[] objects){
        
        try {
            ps=conn.prepareStatement(sql);
            //给占位符赋值
            
            for(int i=0;i<objects.length;i++){
                ps.setObject(i+1, objects[i]);
            }
            rs=ps.executeQuery();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return rs;
    }
// public int setinformation(information to)
// {
//     try {
//        String sql="select * from register where id =?";
//         PreparedStatement ps=conn.prepareStatement(sql);
//        ResultSet k=ps.executeQuery(sql);
//        to.setId(k.getString(0));
//        to.setCode(k.getString(1));
//        to.setShenfen(k.getString(2));
//     } catch (SQLException e) {
//         e.printStackTrace();
//     }
//     return 0;
// }
 
 
}

utilst.java

package utils;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import Bean.teainformation;
//import Bean.information;
public class utilst {
    private static Connection conn=null; 
    private static PreparedStatement ps=null;
     private static ResultSet rs=null;
    static {
             // 定义连接
         

        try {
            // 加载驱动
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/db6", "root", "132956");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public static List<HashMap<String, Object>> getMysqlData() {
        // 预执行加载
        PreparedStatement preparedStatement = null;
        // 结果集
        ResultSet resultSet = null;

        //准备的sql
        String sqlString = "select * from teacher";

        List<HashMap<String, Object>> list = new ArrayList<HashMap<String,Object>>();
        try {
            //预编译
            preparedStatement = conn.prepareStatement(sqlString);
            resultSet = preparedStatement.executeQuery();  //查询
            HashMap<String, Object> map = null;
            while (resultSet.next()) {    //遍历结果集
                map = new HashMap<String, Object>();
                map.put("name", resultSet.getString("name"));   //获取字段名称nickName的值，
                list.add(map);//将nickName的值添加到map中
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (resultSet != null) {
                    resultSet.close();
                }
                if (preparedStatement != null) {
                    preparedStatement.close();
                }
                if (conn != null) {
                    conn.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return list;
    }

    public  int update(String sql,Object[] objects){
        int a=0;
        try {
            
            //创建sql载体
            ps=conn.prepareStatement(sql);
            //给占位符赋值
            for(int i=0;i<objects.length;i++){
                ps.setObject(i+1, objects[i]);
            }
            //操作SQL语句
            a=ps.executeUpdate(); 
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return a;
    }
 public ResultSet query(String sql,Object[] objects){
        
        try {
            ps=conn.prepareStatement(sql);
            //给占位符赋值
            
            for(int i=0;i<objects.length;i++){
                ps.setObject(i+1, objects[i]);
            }
            rs=ps.executeQuery();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return rs;
    }
// public int setinformation(information to)
// {
//     try {
//        String sql="select * from register where id =?";
//         PreparedStatement ps=conn.prepareStatement(sql);
//        ResultSet k=ps.executeQuery(sql);
//        to.setId(k.getString(0));
//        to.setCode(k.getString(1));
//        to.setShenfen(k.getString(2));
//     } catch (SQLException e) {
//         e.printStackTrace();
//     }
//     return 0;
// }
 public void select4(String sql,ArrayList<teainformation> arr)
 {
     
     try {
         //创建sql载体
         ps=conn.prepareStatement(sql);
         ResultSet rs  = ps.executeQuery();
//         System.out.println(rs);
         while(rs.next()) {
         teainformation B = new teainformation();
         B.setTeaname(rs.getString(2));
         arr.add(B);
         
         System.out.println(arr.get(0));
         }
     } catch (SQLException e) {
         e.printStackTrace();
     }
 }
 
}

utilsxuanke.java

package utils;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import Bean.xuanke;
//import Bean.information;
public class utilsxuanke {
    private static Connection conn=null; 
    private static PreparedStatement ps=null;
     private static ResultSet rs=null;
    static {
             // 定义连接
         

        try {
            // 加载驱动
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/db6", "root", "132956");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public static List<HashMap<String, Object>> getMysqlData() {
        // 预执行加载
        PreparedStatement preparedStatement = null;
        // 结果集
        ResultSet resultSet = null;

        //准备的sql
        String sqlString = "select * from xuanke";

        List<HashMap<String, Object>> list = new ArrayList<HashMap<String,Object>>();
        try {
            //预编译
            preparedStatement = conn.prepareStatement(sqlString);
            resultSet = preparedStatement.executeQuery();  //查询
            HashMap<String, Object> map = null;
            while (resultSet.next()) {    //遍历结果集
                map = new HashMap<String, Object>();
                map.put("name", resultSet.getString("name"));   //获取字段名称nickName的值，
                list.add(map);//将nickName的值添加到map中
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (resultSet != null) {
                    resultSet.close();
                }
                if (preparedStatement != null) {
                    preparedStatement.close();
                }
                if (conn != null) {
                    conn.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return list;
    }

    public  int update(String sql,Object[] objects){
        int a=0;
        try {
            
            //创建sql载体
            ps=conn.prepareStatement(sql);
            //给占位符赋值
            for(int i=0;i<objects.length;i++){
                ps.setObject(i+1, objects[i]);
            }
            //操作SQL语句
            a=ps.executeUpdate(); 
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return a;
    }
 public ResultSet query(String sql,Object[] objects){
        
        try {
            ps=conn.prepareStatement(sql);
            //给占位符赋值
            
            for(int i=0;i<objects.length;i++){
                ps.setObject(i+1, objects[i]);
            }
            rs=ps.executeQuery();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return rs;
    }
// public int setinformation(information to)
// {
//     try {
//        String sql="select * from register where id =?";
//         PreparedStatement ps=conn.prepareStatement(sql);
//        ResultSet k=ps.executeQuery(sql);
//        to.setId(k.getString(0));
//        to.setCode(k.getString(1));
//        to.setShenfen(k.getString(2));
//     } catch (SQLException e) {
//         e.printStackTrace();
//     }
//     return 0;
// }
 public void select4(String sql,ArrayList<xuanke> arr)
 {
     
     try {
         //创建sql载体
         ps=conn.prepareStatement(sql);
         ResultSet rs  = ps.executeQuery();
         System.out.println(rs);
         while(rs.next()) {
         xuanke B = new xuanke();
         B.setId(rs.getString(1));
         B.setStuid(rs.getString(2));
         B.setTeaid(rs.getString(3));
         B.setName(rs.getString(4));
         arr.add(B);
         System.out.println(arr.get(0));
         }
     } catch (SQLException e) {
         e.printStackTrace();
     }
 }
 public void select5(String sql,String idnum,ArrayList<xuanke> arr)
 {
     
     try {
         //创建sql载体     
         ps=conn.prepareStatement(sql);
         Object[] objs1={idnum};
         utilsxuanke to=new utilsxuanke();
          ResultSet rs=to.query(sql, objs1);
         while(rs.next()) {
         xuanke B = new xuanke();
         B.setId(rs.getString(1));
         B.setStuid(rs.getString(2));
         B.setTeaid(rs.getString(3));
         B.setName(rs.getString(4));
         arr.add(B);
         }
     } catch (SQLException e) {
         e.printStackTrace();
     }
 }
 
}

 

欢迎各位大佬交流沟通，提供意见。(●'◡'●)