ImageLoader.cs
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using System;
using System.Collections;
using System.IO;
using UnityEngine;
using UnityEngine.Networking;
using UnityEngine.UI;
public static class ImageLoader
{
/// <summary>
/// 加载图片，支持本地缓存
/// </summary>
/// <param name="url">图片地址</param>
/// <param name="targetImage">目标 Image</param>
/// <param name="onSizeReady">图片宽高回调</param>
/// <returns></returns>
public static IEnumerator LoadImage(string url, Image targetImage, Action<int, int> onSizeReady = null)
{
// 生成缓存文件名
string fileName = GetFileNameFromUrl(url);
string cachePath = Path.Combine(Application.temporaryCachePath, fileName);
Texture2D tex = null;
// 1️⃣ 本地有缓存？
if (File.Exists(cachePath))
{
Debug.Log($"[ImageLoader] 加载本地缓存图片: {cachePath}");
byte[] fileData = File.ReadAllBytes(cachePath);
tex = new Texture2D(2, 2); // 临时大小，LoadImage 会自动调整
tex.LoadImage(fileData);
}
else
{
// Debug.Log($"[ImageLoader] 下载图片: {url}");
using (UnityWebRequest uwr = UnityWebRequestTexture.GetTexture(url))
{
yield return uwr.SendWebRequest();
if (uwr.result == UnityWebRequest.Result.Success)
{
tex = DownloadHandlerTexture.GetContent(uwr);
// 保存到本地缓存
byte[] pngData = tex.EncodeToPNG();
File.WriteAllBytes(cachePath, pngData);
// Debug.Log($"[ImageLoader] 下载完成，已缓存到: {cachePath}");
}
else
{
Debug.LogError($"[ImageLoader] 下载失败: {uwr.error}");
yield break;
}
}
}
// 2️⃣ 应用到 UI
if (tex != null && targetImage != null)
{
targetImage.sprite = Sprite.Create(tex, new Rect(0, 0, tex.width, tex.height), new Vector2(1f, 1f));
// 回调宽高
onSizeReady?.Invoke(tex.width, tex.height);
}
}
/// <summary>
/// 从 URL 生成缓存文件名
/// </summary>
private static string GetFileNameFromUrl(string url)
{
if (string.IsNullOrEmpty(url))
return Guid.NewGuid().ToString("N");
// 拆分路径
Uri uri = new Uri(url);
string[] segments = uri.AbsolutePath.Split('/');
if (segments.Length < 2)
return Path.GetFileName(url); // fallback
string folderName = segments[segments.Length - 2]; // 倒数第二段
string fileName = segments[segments.Length - 1]; // 最后一段
// 去掉问号参数部分（如果有）
int index = fileName.IndexOf("?", StringComparison.Ordinal);
if (index >= 0)
{
fileName = fileName.Substring(0, index);
}
// 合并文件名（中间用 - 连接）
string combinedName = $"{folderName}-{fileName}";
// 确保有扩展名，没有则补 ".png"
if (string.IsNullOrEmpty(Path.GetExtension(combinedName)))
{
combinedName += ".png";
}
return combinedName;
}
}