db.java

银行管理系统

import java.sql.*;
//对数据库test的操作类
public class DB{

	Connection con=null;
	PreparedStatement ps = null;
	ResultSet rs = null;
    	
    public DB() {
    	try{
    		Class.forName("com.mysql.jdbc.Driver");
    		con = DriverManager.getConnection(
    			"jdbc:mysql://localhost:3306/test","root","359600");		
    	}catch(ClassNotFoundException e){
    		
    	}catch(SQLException e){
    		
    	}
    }
    
    public boolean login(String username,String password){
    	boolean b = false;
    	try{
    		String sql = "select * from bank_user where name=? and password=?";
    		ps = con.prepareStatement(sql);
    		ps.setString(1,username);
    		ps.setString(2,password);
    		rs = ps.executeQuery();
    		if(rs.next()){
    			b = true;
    		}
    		else{
    			b = false;
    		}
    	}catch(SQLException e){
    		System.out.println (e.getMessage());
    	}
    	return b;
    }
    
    public double queryBalance(String username,String password){
    	double b =0;
		String sql = "select * from bank_user where name=? and password=?";
		try{
			ps = con.prepareStatement(sql);
			ps.setString(1,username);
			ps.setString(2,password);
			rs = ps.executeQuery();
			if(rs.next()){
				b = rs.getDouble("balance");
			}
		}catch(SQLException e){
		}
		return b;
    }
    
    public void getMoney(String username,String password,double amount){
    	try{
    		String sql = "update bank_user set balance=balance-? where name=? and password=?";
    		ps = con.prepareStatement(sql);
    		ps.setDouble(1,amount);
    		ps.setString(2,username);
    		ps.setString(3,password);
    		ps.executeUpdate();
    	}catch(SQLException e){
    	}
    }
    
    public void addMoney(String username,String password,double amount){
    	try{
    		String sql = "update bank_user set balance=balance+? where name=? and password=?";
    		ps = con.prepareStatement(sql);
    		ps.setDouble(1,amount);
    		ps.setString(2,username);
    		ps.setString(3,password);
    		ps.executeUpdate();
    	}catch(SQLException e){
    	}
    }
    public String rework(String username,String repassword)
    {
    	try{
    		String sql = "update bank_user set password=? where name=?";
    		ps = con.prepareStatement(sql);
    		ps.setString(1,repassword);
    		ps.setString(2,username);
    		ps.executeUpdate();
    	}catch(SQLException e){
    	}
    	return repassword;
    }
}