MySQL连接样例！

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;

public class OperateDB ...{
    
    public static ResultSet queryDB(String sql)throws ClassNotFoundException...{
        Connection con=null;
        Statement stmt=null;
        ResultSet rs=null;
        //StringBuffer sb=new StringBuffer();
        try...{
            //Class.forName("com.mysql.jdbc.Driver");
            con=OperateDB.getConnection(con);
            //con=DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/menagerie","root","333");
            stmt=con.createStatement();
            rs=stmt.executeQuery(sql);
        }catch(Exception e)...{
            e.printStackTrace();
        }

        return rs;
    }
    public static int updateDB(String sql)throws ClassNotFoundException...{

        Statement sm=null;
        Connection con=null;
        int affectRows=0;
        try...{
            con=OperateDB.getConnection(con);
            //con=DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/menagerie","root","333");
            sm=con.createStatement();
            affectRows=sm.executeUpdate(sql);
        }catch(Exception e)...{
            e.printStackTrace();
            System.out.println("error updateDB!");
            affectRows=Statement.EXECUTE_FAILED;
        }finally...{
            closeStatement(sm);
        }
            
        return affectRows;
            
    }
    public static void closeStatement(Statement sm)...{
        if(sm!=null)...{
            try...{
                sm.close();
            }catch(SQLException e)...{
                e.printStackTrace();
            }
        }
    }
    /**//*public static void showResultSet(ResultSet rs){
        if(rs==null){
            return;
        }
        try{
            ResultSetMetaData md=rs.getMetaData();
            int columnCount = md.getColumnCount();
            if(!rs.isBeforeFirst()){
                rs.beforeFirst();
            }
            while(rs.next()){
                for(int i=0;i<columnCount;i++){
                    System.out.print(rs.getObject(i)+" ");
                }
                System.out.print(rs.getObject(columnCount)+" ");
                rs.beforeFirst();
            }
        }catch(SQLException e){
            e.printStackTrace();
        }
    }*/
    public static Connection getConnection(Connection con) throws ClassNotFoundException...{
        try...{    
            Class.forName("com.mysql.jdbc.Driver");
            if(con==null)...{
            
                con=DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/menagerie","root","333");
            }
        }catch(SQLException e)...{
            e.printStackTrace();
        }
        return con;
    }
    public static void closeConnection(Connection con)...{
        if(con!=null)...{
            try...{
                con.close();
            }catch(SQLException e)...{
                e.printStackTrace();
            }
        }
    }
    
    public static void main(String []args) throws ClassNotFoundException...{
        String sql="";
        ResultSet rs=null;
        Connection con=null;
        Statement sm=null;
        int inte=0;
        sql="select * from pet;";
        String updatesql="update pet set sex=null where birth='1997-12-09'";
        try...{
            rs=OperateDB.queryDB(sql);
            //OperateDB.showResultSet(rs);
            while(rs.next())...{
                System.out.println(rs.getObject("name"));
            }
            inte=OperateDB.updateDB(updatesql);
            System.out.println("updateDB= "+inte);
        }catch(Exception e)...{
            e.printStackTrace();
        }
        finally...{
            try...{
                rs.close();
            }catch(SQLException e)...{
                e.printStackTrace();
            }
            
            closeStatement(sm);
            closeConnection(con);
        }
        
        
    }
}