jdbc怎么连接数据库

import java.sql.*;

public class ConnDB {
private Connection cn;
private Statement stmt;
private ResultSet rs;
public boolean open(String host,String dbname,String sUsr,String sPwd)
{
try {
Class.forName("com.mysql.jdbc.Driver");
String url="jdbc:mysql://"+host+":3306"+"/"+dbname;
cn=(Connection) DriverManager.getConnection(url,sUsr,sPwd);
stmt=(Statement)cn.createStatement();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
return false;

}catch(SQLException e){
e.printStackTrace();
}
return true;}
public boolean close(){

try{
cn.close();
stmt.close();
rs.close();
}
catch(SQLException sqlex)
{sqlex.printStackTrace();
return false; }

return true;
}
public Res