PHP编程：PHP实现货币换算的方法

<?php
/*
* File: CurrencyConverter.php
* Author: Simon Jarvis
* Copyright: 2005 Simon Jarvis
* Date: 10/12/05
* Link: http://www.white-hat-web-design.co.uk/articles/php-currency-conversion.php
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License,or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details:
* http://www.gnu.org/licenses/gpl.html
*
*/
class CurrencyConverter {
?? var $xml_file = "www.ecb.int/stats/eurofxref/eurofxref-daily.xml";
?? var $mysql_host,$mysql_user,$mysql_pass,$mysql_db,$mysql_table;
?? var $exchange_rates = array();
?? //Load Currency Rates
?? function CurrencyConverter($host,$user,$pass,$db,$tb) {
????? $this->mysql_host = $host;
????? $this->mysql_user = $user;
????? $this->mysql_pass = $pass;
????? $this->mysql_db = $db;
????? $this->mysql_table = $tb;
????? $this->checkLastUpdated();
????? $conn = mysql_connect($this->mysql_host,$this->mysql_user,$this->mysql_pass);
????? $rs = mysql_select_db($this->mysql_db,$conn);
????? $sql = "SELECT * FROM ".$this->mysql_table;
????? $rs =? mysql_query($sql,$conn);
????? while($row = mysql_fetch_array($rs)) {
???????? $this->exchange_rates[$row['currency']] = $row['rate'];
????? }
?? }
?? /* Perform the actual conversion,defaults to ￡1.00 GBP to USD */
?? function convert($amount=1,$from="GBP",$to="USD",$decimals=2) {
????? return(number_format(($amount/$this->exchange_rates[$from])*$this->exchange_rates[$to],$decimals));
?? }
?? /* Check to see how long since the data was last updated */
?? function checkLastUpdated() {
????? $conn = mysql_connect($this->mysql_host,$conn);
????? $sql = "SHOW TABLE STATUS FROM ".$this->mysql_db." LIKE '".$this->mysql_table."'";
????? $rs =? mysql_query($sql,$conn);
????? if(mysql_num_rows($rs) == 0 ) {
???????? $this->createTable();
????? } else {
???????? $row = mysql_fetch_array($rs);
???????? if(time() > (strtotime($row["Update_time"])+(12*60*60)) ) {
??????????? $this->downloadExchangeRates();
???????? }
????? }
?? }
?? /* Download xml file,extract exchange rates and store values in database */
?? function downloadExchangeRates() {
????? $currency_domain = substr($this->xml_file,strpos($this->xml_file,"/"));
????? $currency_file = substr($this->xml_file,"/"));
????? $fp = @fsockopen($currency_domain,80,$errno,$errstr,10);
????? if($fp) {
???????? $out = "GET ".$currency_file." HTTP/1.1rn";
???????? $out .= "Host: ".$currency_domain."rn";
???????? $out .= "User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8) Gecko/20051111 Firefox/1.5rn";
???????? $out .= "Connection: Closernrn";
???????? fwrite($fp,$out);
???????? while (!feof($fp)) {
??????????? $buffer .= fgets($fp,128);
???????? }
???????? fclose($fp);
???????? $pattern = "{<Cubes*currency='(w*)'s*rate='([d.]*)'/>}is";
???????? preg_match_all($pattern,$buffer,$xml_rates);
???????? array_shift($xml_rates);
???????? for($i=0;$i<count($xml_rates[0]);$i++) {
??????????? $exchange_rate[$xml_rates[0][$i]] = $xml_rates[1][$i];
???????? }
???????? $conn = mysql_connect($this->mysql_host,$this->mysql_pass);
???????? $rs = mysql_select_db($this->mysql_db,$conn);
???????? foreach($exchange_rate as $currency=>$rate) {
??????????? if((is_numeric($rate)) && ($rate != 0)) {
?????????????? $sql = "SELECT * FROM ".$this->mysql_table." WHERE currency='".$currency."'";
?????????????? $rs =? mysql_query($sql,$conn) or die(mysql_error());
?????????????? if(mysql_num_rows($rs) > 0) {
????????????????? $sql = "UPDATE ".$this->mysql_table." SET rate=".$rate." WHERE currency='".$currency."'";
?????????????? } else {
????????????????? $sql = "INSERT INTO ".$this->mysql_table." VALUES('".$currency."',".$rate.")";
?????????????? }
?????????????? $rs =? mysql_query($sql,$conn) or die(mysql_error());
??????????? }
???????? }
????? }
?? }
?? /* Create the currency exchange table */
?? function createTable() {
????? $conn = mysql_connect($this->mysql_host,$conn);
????? $sql = "CREATE TABLE ".$this->mysql_table." ( currency char(3) NOT NULL default '',rate float NOT NULL default '0',PRIMARY KEY(currency) ) ENGINE=MyISAM";
????? $rs =? mysql_query($sql,$conn) or die(mysql_error());
????? $sql = "INSERT INTO ".$this->mysql_table." VALUES('EUR',1)";
????? $rs =? mysql_query($sql,$conn) or die(mysql_error());
????? $this->downloadExchangeRates();
?? }
}
?>

<?php
?? include('CurrencyConverter.php');
?? $x = new CurrencyConverter('your_host','your_username','your_password','your_database_name','your_table_name');
?? echo $x->convert(2.50,'GBP','USD');
?>