即時匯率換算系統的實作
===
帶入金額-及時換算匯率-的程式
===
###帶入金額-和貨幣代碼 轉換成顯示出含貨幣前置符號的金額
**D:\wamp\www\o03\system\library\cart\currency.php 這支**
```php
$this->currency->format($result['tax'], $this->config->get('config_currency')),//帶入金額-和貨幣代碼 轉換成顯示出含貨幣前置符號的金額
$this->currency->format(金額, 貨幣代碼一般是TWD) //帶入金額-轉換成顯示出含貨幣前置符號的金額
//$this->currency->format(金額, 貨幣代碼一般是TWD,匯率=不輸入就是用資料庫的,是否不顯示貨幣符號)
currency
```
-----------------------------------------------
使用Yahoo API 抓取即時匯率
===
http://myskilltree.blogspot.tw/2016/03/yahoo-api.html
您可以在 http://www.xe.com/iso4217.php 找到完整的 ISO 貨幣代碼及設定。
-----------------------------------------------
```php
http://download.finance.yahoo.com/d/quotes.csv?e=.csv&f=c4l1&s=TWDUSD=x,TWDJPY=x 2總幣的兌換比例
http://download.finance.yahoo.com/d/quotes.csv?e=.json&f=c4l1&s=TWDUSD=x,TWDJPY=x
```
其中URL裡的f=c4l1是只取下兌換幣別(美金)的代碼與匯率
如果想取下更詳細的資料可以換成f=sl1d1t1，分別指定了代碼(含原始幣別跟對換幣別)、匯率、日期、時間這四個欄位
而s=TWDUSD=x ，其中TWD (新台幣) 為原始幣別 USD (美金)為兌換幣別，可以依需求自行更換，如果要查詢多筆資料則在後在後接續即可。
-----------------------------------------------
#OPENCART 3.0 的匯率系統 解析
-----------------------------------------------
1.它用curl抓取了yahoo的關於匯率的數據，
D:\wamp\www\o06\admin\model\localisation\currency.php 這只有首頁 才會讀取
$curl = curl_init();
//就是這裡了，看到木有
curl_setopt($curl, CURLOPT_URL, 'http://download.finance.yahoo.com/d/quotes.csv?s=' . implode(',', $currency_data) . '&f=sl1&e=.json');
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
它用curl抓取了yahoo的關於匯率的數據，結合這2段代碼可以看出，其實它的功能就是打開這個頁面的時候自動更新數據庫中匯率數據。
到此問題找到原因了，那麼解決的方法總結一下：
可以關閉自動更新匯率（Dashboard>System>Setting>Your Store>edit>local>Auto Update Currency 選擇No）
系統管理=>商店管理.編輯=>本地化設定=>匯率自動更新
系統管理=>在地化管理=>幣別管理
後台一天抓一次匯率的程式
===
**D:\wamp\www\o03\admin\controller\common\dashboard.php**
```php
// Run currency update
if ($this->config->get('config_currency_auto')) {
$this->load->model('localisation/currency');
$this->model_localisation_currency->refresh(false);//執行後台一天抓一次匯率的程式
}
```
**D:\wamp\www\o03\admin\model\localisation\currency.php**
```php
//抓取匯率資料-入資料庫 參數=false 是自己國家以外，更新資料抓取時間大於1天的 ，參數=true自己國家以外資料全更新
public function refresh($force = false) {
$data = array();
if ($force) {
$query = $this->db->query("SELECT * FROM " . DB_PREFIX . "currency WHERE code != '" . $this->db->escape($this->config->get('config_currency')) . "'");
} else {
//SELECT * FROM oc_currency WHERE code != 'TWD' AND date_modified < '2017-08-30 14:20:18' 自己國家以外，更新資料抓取時間大於1天的
$query = $this->db->query("SELECT * FROM " . DB_PREFIX . "currency WHERE code != '" . $this->db->escape($this->config->get('config_currency')) . "' AND date_modified < '" . $this->db->escape(date('Y-m-d H:i:s', strtotime('-1 day'))) . "'");
}
//組合文字把貨幣代碼加上=X
foreach ($query->rows as $result) {
$data[] = $this->config->get('config_currency') . $result['code'] . '=X';
}
$url='http://download.finance.yahoo.com/d/quotes.csv?s=' . implode(',', $data) . '&f=sl1&e=.csv';
//去線上抓取資料
$curl = curl_init();
curl_setopt($curl, CURLOPT_URL,$url);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($curl, CURLOPT_HEADER, false);
curl_setopt($curl, CURLOPT_CONNECTTIMEOUT, 30);
curl_setopt($curl, CURLOPT_TIMEOUT, 30);
$content = curl_exec($curl);
curl_close($curl);
/*
送出去的網址
http://download.finance.yahoo.com/d/quotes.csv?s=TWDCNY=X,TWDHKD=X,TWDGBP=X,TWDUSD=X,TWDEUR=X&f=sl1&e=.csv"TWDCNY=X",0.2180
抓回來資料
"TWDHKD=X",0.2587
"TWDGBP=X",0.0256
"TWDUSD=X",0.0331
"TWDEUR=X",0.0279
echo $url,"<br>\n";print($content);
*/
$lines = explode("\n", trim($content));
/*把抓回來的資料處理*/
foreach ($lines as $line) {
$currency = utf8_substr($line, 4, 3);
$value = utf8_substr($line, 11, 6);//匯率
//更新全部匯率
if ((float)$value) {
$this->db->query("UPDATE " . DB_PREFIX . "currency SET value = '" . (float)$value . "', date_modified = '" . $this->db->escape(date('Y-m-d H:i:s')) . "' WHERE code = '" . $this->db->escape($currency) . "'");
}
}
//更新我國匯率為1.00000
$this->db->query("UPDATE " . DB_PREFIX . "currency SET value = '1.00000', date_modified = '" . $this->db->escape(date('Y-m-d H:i:s')) . "' WHERE code = '" . $this->db->escape($this->config->get('config_currency')) . "'");
$this->cache->delete('currency');//刪除緩存檔案
}
```
帶入金額-及時換算匯率-的程式
===
D:\wamp\www\o03\system\library\cart\currency.php 是這支
```php
<?php
namespace Cart;
class Currency {
private $currencies = array();
public function __construct($registry) {
$this->db = $registry->get('db');
$this->language = $registry->get('language');
$query = $this->db->query("SELECT * FROM " . DB_PREFIX . "currency");//資料庫查出數據
foreach ($query->rows as $result) {
$this->currencies[$result['code']] = array(
'currency_id' => $result['currency_id'],//貨幣代號
'title' => $result['title'],//貨幣名稱
'symbol_left' => $result['symbol_left'],//貨幣符號金額左邊顯示（eg:$32、￥45、）
'symbol_right' => $result['symbol_right'],//貨幣符號金額右邊顯示
'decimal_place' => $result['decimal_place'],//保留小數點後幾位有效數字
'value' => $result['value']//匯率
);
}
}
//帶入金額-轉換成顯示出含貨幣前置符號的金額$this->currency->format(金額, 貨幣代碼一般是TWD)
//$this->currency->format(金額, 貨幣代碼一般是TWD,匯率=不輸入就是用資料庫的,是否不顯示貨幣符號)
public function format($number, $currency, $value = '', $format = true) {
$symbol_left = $this->currencies[$currency]['symbol_left'];
$symbol_right = $this->currencies[$currency]['symbol_right'];
$decimal_place = $this->currencies[$currency]['decimal_place'];
if (!$value) {
$value = $this->currencies[$currency]['value'];
}
//金額浮點數*匯率
$amount = $value ? (float)$number * $value : (float)$number;
$amount = round($amount, (int)$decimal_place);//金額取到小數幾位
//是否不顯示貨幣符號
if (!$format) {
return $amount;
}
//以下顯示貨幣符號
$string = '';
if ($symbol_left) {
$string .= $symbol_left;
}
//千進位加標點函式
$string .= number_format($amount, (int)$decimal_place, $this->language->get('decimal_point'), $this->language->get('thousand_point'));
if ($symbol_right) {
$string .= $symbol_right;
}
return $string;//返回有貨幣符號的金額
}
public function convert($value, $from, $to) {
if (isset($this->currencies[$from])) {
$from = $this->currencies[$from]['value'];
} else {
$from = 1;
}
if (isset($this->currencies[$to])) {
$to = $this->currencies[$to]['value'];
} else {
$to = 1;
}
return $value * ($to / $from);
}
//返回貨幣代號
public function getId($currency) {
if (isset($this->currencies[$currency])) {
return $this->currencies[$currency]['currency_id'];
} else {
return 0;
}
}
//返回貨幣符號
public function getSymbolLeft($currency) {
if (isset($this->currencies[$currency])) {
return $this->currencies[$currency]['symbol_left'];
} else {
return '';
}
}
public function getSymbolRight($currency) {
if (isset($this->currencies[$currency])) {
return $this->currencies[$currency]['symbol_right'];
} else {
return '';
}
}
public function getDecimalPlace($currency) {
if (isset($this->currencies[$currency])) {
return $this->currencies[$currency]['decimal_place'];
} else {
return 0;
}
}
public function getValue($currency) {
if (isset($this->currencies[$currency])) {
return $this->currencies[$currency]['value'];
} else {
return 0;
}
}
//返回貨幣資料
public function has($currency) {
return isset($this->currencies[$currency]);
}
}
```
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