dbc.java~3~

用java编写的实现图书管理系统系统的功能

package mydbc.dbc;
import java.sql.*;

/**
 * <p>Title: </p>
 *
 * <p>Description: </p>
 *
 * <p>Copyright: Copyright (c) 2008</p>
 *
 * <p>Company: </p>
 *
 * @author not attributable
 * @version 1.0
 */
public class DBC {
    public String url;
    public Connection conn;
    public DBC only;
    
    public DBC getInstance(){
        
        if(only == null){
            return new DBC();
        }else{
            return only;
        }
    }
    
    public void getConnection(){
        
        try {
            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
            conn = DriverManager.getConnection(url);
        } catch (SQLException ex) {
            javax.swing.JOptionPane.showMessageDialog(null,ex.getMessage().toString());
        } catch (ClassNotFoundException ex) {
            javax.swing.JOptionPane.showMessageDialog(null,ex.getMessage().toString());
        }
    }
    public ResultSet executeQuery(String sql){
        
        ResultSet rs = null;
        try {
            getConnection();
            Statement stmt = conn.createStatement();
            rs = stmt.executeQuery(sql);
            return rs;
        } catch (SQLException ex) {
            javax.swing.JOptionPane.showMessageDialog(null,ex.getMessage().toString());
            return null;
        }
    }
    
    public boolean executeUpdate(String sql){
        
        getConnection();
        Statement stmt = conn.createStatement();
        int i = stmt.executeUpdate(sql);
        stmt.close();
        conn.close();
        if(i > 0){
            return true;
        }else{
            return false;
        }
    }
}