第十五次作业

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。

 

package ccut.java.lsq;
import java.sql.*;
import java.util.*;
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();
        }
    }

    DB(){
        try{
            con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test","root","");
        }catch(SQLException e){
            e.printStackTrace();
        }
    }

    public static DB getInstabce(){
        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                    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                    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();
        }
    }
}
public class TestMain {
    public static void main(String[] args) {
        Scanner input=new Scanner(System.in);
        String username=input.next();
        String password=input.next();
        ResultSet a;
        ResultSet b;
        DB db = new DB();
        a = db.executeSelect("select * from t_login where username = '"+username+"' and password = '"+password+"'", args);
        try {
            if (a.next()) {
                System.out.println("登录成功");
                System.out.println("以下为t_user表中的信息：");
                b = db.executeSelect("select * from t_user", args);
                while(b.next()) {
                    int id = b.getInt(1);
                    String name = b.getString(2);
                    int sex = b.getInt(3);
                    String birthday = b.getString(4);
                    System.out.println("id:"+id+"\tname:"+name+"\tsex:"+sex+"\tbirthday:"+birthday);
                }
                System.out.println("请输入插入信息：");
                int id1 = input.nextInt();
                String name1 = input.next();
                int sex1 = input.nextInt();
                String date1 = input.next();
                String sql="insert into t_user(id,name,sex,birthday) values("+id1+",'"+name1+"',"+sex1+",'"+date1+"')";
                int n = db.executeModify(sql, args);
                if(n>0) {
                    System.out.println("插入成功");
                }else {
                    System.out.println("插入失败");
                }
            }else {
                System.out.println("登陆失败");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }}