48 lines
1.2 KiB
Go
48 lines
1.2 KiB
Go
package service
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import (
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"net/http"
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"strings"
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)
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// DetectFileType 根据返回的二进制内容推断 contentType + 扩展名（尽量稳定）
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func DetectFileType(data []byte) (contentType string, ext string) {
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if len(data) == 0 {
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return "application/octet-stream", ""
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}
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ct := http.DetectContentType(data)
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// http.DetectContentType 可能带 charset 等参数：text/plain; charset=utf-8
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if idx := strings.Index(ct, ";"); idx > 0 {
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ct = strings.TrimSpace(ct[:idx])
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}
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switch ct {
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case "audio/mpeg":
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return ct, ".mp3"
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case "audio/wave", "audio/wav", "audio/x-wav":
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return ct, ".wav"
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case "video/mp4":
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return ct, ".mp4"
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case "image/png":
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return ct, ".png"
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case "image/jpeg":
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return ct, ".jpg"
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case "application/pdf":
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return ct, ".pdf"
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case "text/plain":
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return ct, ".txt"
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case "application/json":
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return ct, ".json"
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default:
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// 兜底：尝试从 ct 截取 subtype 作为后缀（例如 application/json）
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if parts := strings.Split(ct, "/"); len(parts) == 2 {
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sub := parts[1]
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// 避免出现 "plain; charset=utf-8" 之类的后缀
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if idx := strings.Index(sub, ";"); idx > 0 {
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sub = strings.TrimSpace(sub[:idx])
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}
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return ct, "." + sub
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}
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return ct, ""
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}
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}
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