feat: 添加图像缓存系统以优化远程图片加载性能

新增img.php文件，旧版本文件，一个开源项目的原始文件。

img.php

@@ -0,0 +1,69 @@
+<?php
+/*
+'图像缓存系统'
+使用方式传入远程图片地址例如：
+/img.php?url=https://www.baidu.com/img/flexible/logo/pc/result.png
+*/
+error_reporting(E_ERROR | E_PARSE);
+@ini_set('max_execution_time', '0');
+@ini_set("memory_limit",'-1');
+$url = $_GET["url"];
+if (!empty($url) && substr($url, 0, 4) == 'http') {
+    $dir = pathinfo($url);
+    $host = $dir['dirname'];
+    $ext = $dir['extension'];
+    $refer = $host.'/';
+    $ch = curl_init($url);
+    curl_setopt($ch, CURLOPT_REFERER, $refer);
+    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
+    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
+    curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 15);
+    curl_setopt($ch, CURLOPT_TIMEOUT, 30);
+    curl_setopt($ch, CURLOPT_HEADER, 0);
+    curl_setopt($ch, CURLOPT_POST, 0);
+    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 0);
+    curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 1);
+    curl_setopt($ch, CURLOPT_BINARYTRANSFER, 1);
+    $data = @curl_exec($ch);
+    curl_close($ch);
+    
+    $types = array(
+        'gif' => 'image/gif',
+        'jpeg' => 'image/jpeg',
+        'jpg' => 'image/jpeg',
+        'jpe' => 'image/jpeg',
+        'png' => 'image/png',
+        'webp' => 'image/webp',
+    );
+    $type = $types[$ext] ? $types[$ext] : 'image/jpeg';
+    
+    header("Content-type: ".$type);
+    
+    // 缓存图片
+    $cacheDir = 'cache'; // 缓存文件夹
+    
+    // 根据被缓存的网址创建文件夹
+    $parsedUrl = parse_url($url);
+    $domain = $parsedUrl['host'];
+    $cacheSubDir = $cacheDir . '/' . $domain;
+    if (!file_exists($cacheSubDir)) {
+        mkdir($cacheSubDir, 0777, true); // 创建缓存子文件夹
+    }
+    
+    // 获取原始图片名称
+    $imageName = basename($url);
+    
+    $cachedImagePath = $cacheSubDir . '/' . $imageName; // 缓存图片路径
+    
+    if (file_exists($cachedImagePath)) {
+        // 返回缓存图片
+        readfile($cachedImagePath);
+    } else {
+        // 保存原始图片内容到缓存文件夹
+        file_put_contents($cachedImagePath, $data);
+        
+        // 输出原始图片
+        echo $data;
+    }
+}
+?>