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。

源程序：

package bb;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.*;
public class text {

	
	public static void main(String[] args) {
		Scanner reader=new Scanner(System.in);
		System.out.println("请输入名字：");
		String username=reader.next();
		System.out.println("请输入密码：");
		String password=reader.next();
		Connection con=null;
		Statement st=null;
		PreparedStatement p=null;
		try {
			Class.forName("com.mysql.jdbc.Driver");
			try {
				con=DriverManager.getConnection("jdbc:mysql://localhost:3306/t_login1","root","1234");
				p=con.prepareStatement("select*from ss where username=? and password=?");
				p.setString(1, username);
				p.setString(2,password);
				ResultSet r=p.executeQuery();
				if(r.next()){
					System.out.println("登录成功！");
				}
				else{
					System.out.println("登录失败！");
				}
				if(r!=null){
					r.close();
				}
			} catch (SQLException e) {
				
				e.printStackTrace();
			}
			
		} catch (ClassNotFoundException e) {
			
			e.printStackTrace();
		}
		finally{
			try {
				p.close();
			} catch (SQLException e1) {
				
				e1.printStackTrace();
			}
			try {
				con.close();
			} catch (SQLException e) {
				
				e.printStackTrace();
			}
		}

	}

}

　　运行结果

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。

源程序

public class DB {
    private Connection con;
    private PreparedStatement pre;
    private ResultSet rs;
    private static DB db;

    public static DB getInstance() {
        if (db == null) {
            db = new DB();
        }
        return db;
    }

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

    static {
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    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) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        
    }

　　

public class user {
    public static void main(String[] args) {
        DB db=DB.getInstance();
        Scanner reader = new Scanner(System.in);
        System.out.print("请输入用户名和密码:
");
        String username = reader.nextLine();
        String password = reader.nextLine();
        ResultSet rs = db.executeselect("select * from t1  where username=? and password=?", new Object[] {username,password});
        try {
            if (rs.next()) {
                System.out.print("登陆成功!
" + "t3表的内容是
");
                ResultSet rs1 = db.executeselect("select*from t3",new Object[]{});
                while (rs1.next()) {
                    String name = rs1.getString(2);
                    String sex = rs1.getString(3);
                    String birthday = rs1.getString(4);
                    System.out.println("name:" + name);
                    System.out.println("sex:" + sex);
                    System.out.println("birthday:" + birthday);
                }
                System.out.print("请输入您的name,sex,birthday
");
                String name = reader.nextLine();
                String sex = reader.nextLine();
                String birthday = reader.nextLine();
                int count=db.executeModify("insert into t3(name,sex,birthday)values(?,?,?)", new Object[]{name,sex,birthday});
                    if (count > 0) {
                        System.out.print("数据更新成功");
                    } else {
                        System.out.print("数据更新失败");
                    }
                }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        db.close();
    }
}

　　运行结果