• 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。

    DB类

        import java.sql.Connection;
        import java.sql.DriverManager;
        import java.sql.PreparedStatement;
        import java.sql.ResultSet;
        import java.sql.SQLException;
    
        public class DB {
            private Connection con;
            private PreparedStatement pre;
            private ResultSet rs;
            private static DB test;
            
            static {
                try {
                    Class.forName("com.mysql.jdbc.Driver");
                } catch (ClassNotFoundException e) {
                    e.printStackTrace();
                }
            }
            
            private DB() {
                try {
                    con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test","root","");
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
    
            public static DB getInstance() {
                if (test == null) {
                    test = new DB();
                }
                return test;
            }
    
            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();
                }
            }
        }

    Testmain类

    import java.sql.*;
    import java.util.Scanner;
    
    public class Testmain {
        public static void main(String[] args) {
            Scanner r = new Scanner(System.in);
            System.out.println("请输入用户名和密码:");
            String  username = r.next();
            String password = r.next();
            Connection con = null;
            Statement st = null;
            ResultSet rs=null;
    
            try {
                Class.forName("com.mysql.jdbc.Driver");
                try {
                    con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test","root","");
                } catch (SQLException e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                }
                try {
                    st = con.createStatement();
                } catch (SQLException e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                }
                String sql ="insert into t_login(username,password) values('" +username+ "','" + password + "')";
    
                int count = 0;
                try {
                    count = st.executeUpdate(sql);
                } catch (SQLException e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                } 
                if(count>0) {
                    System.out.println("登陆成功");
                    rs= DB.getInstance().executeSelect("select * from t_user", args);   //调用方法,查询表中信息
    
                    try {
                        while(rs.next()) {  //循环输出
                            int id = rs.getInt(1);
                            String name = rs.getString(2);
                            int sex = rs.getInt(3);
                            String birthday = rs.getString(4);
                            System.out.println("id	"+"name	"+"sex	"+"birthday");
                            System.out.println(id + "	" + name + "	" + sex + "	" + birthday);
                        }
                    } catch (SQLException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                    
                    
                    System.out.println("请输入id,name,sex,birthday:");//增加一条记录
                    String id=r.next();
                    String name=r.next();
                    Integer sex = Integer.valueOf(r.next());
                    String birthday = r.next();
                    String sql1="insert into t_user(id,name,sex,birthday) values('"+id+"','"+name+"','"+sex+"','"+birthday+"')";
                    int Count=DB.getInstance().executeModify(sql1, args);
                    if(Count>0)
                        System.out.println("添加成功");
                    else
                        System.out.println("添加失败,填写有误");
                }
                else
                    System.out.println("登陆失败");
    
    
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            }finally {
                try {
                    st.close();
                    con.close();
                }catch (SQLException e){
                    e.printStackTrace();
                }
            }
        }
    }

    运行截图

     

     

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  • 原文地址:https://www.cnblogs.com/TI-NA/p/12045872.html
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