• 第15周作业


    题目1:编写一个应用程序,输入用户名和密码,访问test数据库中t_login表(字段包括id、username、password),验证登录是否成功。

    题目2:在上一题基础上,当登录成功后,将t_user表(id、name、sex、birthday)的信息进行显示(要求使用DB.java完成登录和获取t_user表中数据的操作),最后再对t_user表进行一条记录的添加操作。


    代码:

    package Example12_11;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.util.Scanner;
    import Example12_12.DB;
    public class Test12_12 {
        public static void main(String[] args) {
            // TODO Auto-generated method stub
            Scanner reader = new Scanner(System.in);
            String x = reader.next();
            String y = reader.next();
            ResultSet verify;        //验证username password是否正确
            ResultSet query;        //查询t_user表中内容
            DB db = new DB();    
            verify = db.executeSelect("select * from t_login where username = '"+x+"' and password = '"+y+"'", args);    //验证账户密码
            try {
                if (verify.next()) {
                    System.out.println("登录成功");
                    System.out.println("t_user表中的信息");
                    query = db.executeSelect("select * from t_user", args);        //获取t_user表中信息
                    while(query.next()) {
                        int id = query.getInt(1);
                        String name = query.getString(2);
                        int sex = query.getInt(3);
                        String birthday = query.getString(4);
                        System.out.println("id:"+id+"	name:"+name+"	sex:"+sex+"	birthday:"+birthday);    
                    }
                    System.out.println("请输入需要添加的记录:");
                    int newid = reader.nextInt();
                    String newname = reader.next();
                    int newsex = reader.nextInt();
                    String newdate = reader.next();
                    String sql="insert into t_user(id,name,sex,birthday) values("+newid+",'"+newname+"',"+newsex+",'"+newdate+"')";    //记录添加操作
                    int n = db.executeModify(sql, args);    
                    if(n>0) {
                        System.out.println("数据插入成功");
                    }else {
                        System.out.println("数据插入失败");
                    }
                }else {
                    System.out.println("登陆失败");
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    
    }

    DB.java代码:

    package Example12_12;
    import java.sql.*;
    public class DB {
        private Connection con;
        private PreparedStatement pre;
        private ResultSet rs;
        private static DB db;
        static {
            try {
                Class.forName("com.mysql.cj.jdbc.Driver");
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            }
        }
        public DB() {
            try {
                con = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydatabase?useSSL=false&serverTimezone=UTC","root","1234");
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        public static DB getInstance() {
            if(db == null) {
                db = new DB();
            }
            return db;
        }
        public ResultSet executeSelect (String sql, Object[] args) {
            try {
                pre = con.prepareStatement(sql);
                if(args.length !=0) {
                    for(int i = 0;i< args.length;i++) {
                        pre.setObject(i+1, args[i]);
                    }
                }
                rs = pre.executeQuery();
            } catch (SQLException e) {
                e.printStackTrace();
            }
            return rs;
        }
        public int executeModify (String sql, Object[] args) {
            int n = 0;
            try {
                pre = con.prepareStatement(sql);
                if(args.length !=0) {
                    for(int i = 0;i< args.length;i++) {
                        pre.setObject(i+1, args[i]);
                    }
                }
                n = pre.executeUpdate();
            } catch (SQLException e) {
                e.printStackTrace();
            }
            return n;
        }
        public void close() {
            try {
                if (rs != null) {
                    rs.close();
                }
                pre.close();
                con.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        
    }

    运行截图:

      验证登录,成功后将t_user表信息进行显示:

      

      数据库t_login表中内容:                       数据库t_user表中内容            

                    

      

      对t_user表进行一条记录添加:

      

      添加后数据库t_user表中内容:

      

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  • 原文地址:https://www.cnblogs.com/xushaohua/p/12029871.html
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