add:

更新

backend/IM_API/Tools/CodeDefine.cs

@@ -105,5 +105,11 @@
         // 3.9 会话相关错误（3100 ~ 3199）
         /// <summary>发送时异常</summary>
         public static CodeDefine CONVERSATION_NOT_FOUND = new CodeDefine(3100, "会话不存在");
+
+        // 3.9 文件相关错误（3200 ~ 3299）
+        /// <summary>分片不存在异常</summary>
+        public static CodeDefine CHUNKE_NOT_FOUND = new CodeDefine(3201, "分片不存在");
+        /// <summary>分片合并异常</summary>
+        public static CodeDefine CHUNKE_COMBINE_FAIL = new CodeDefine(3202, "分片合并失败");
     }
 }

backend/IM_API/Tools/ObjectNameGenerator.cs

@@ -0,0 +1,51 @@
+namespace IM_API.Tools
+{
+    public static class ObjectNameGenerator
+    {
+        public static string Generate(ObjectNameContext ctx)
+        {
+            var ext = GetExtension(ctx.FileName, ctx.ContentType);
+            var shortId = Guid.NewGuid().ToString("N")[..12];
+
+            var parts = new List<string>
+        {
+            ctx.Biz,
+            ctx.Now.Year.ToString(),
+            ctx.Now.Month.ToString("D2")
+        };
+
+            if (ctx.UserId.HasValue)
+            {
+                parts.Add(ctx.UserId.Value.ToString());
+            }
+
+            parts.Add($"{shortId}{ext}");
+
+            return string.Join("/", parts);
+        }
+
+        private static string GetExtension(string fileName, string contentType)
+        {
+            var ext = Path.GetExtension(fileName);
+            if (!string.IsNullOrWhiteSpace(ext))
+                return ext.ToLowerInvariant();
+
+            return contentType switch
+            {
+                "image/jpeg" => ".jpg",
+                "image/png" => ".png",
+                "video/mp4" => ".mp4",
+                _ => ".bin"
+            };
+        }
+    }
+    public class ObjectNameContext
+    {
+        public string Biz { get; init; } = "IM";
+        public long? UserId { get; init; }
+        public string FileName { get; init; } = default!;
+        public string ContentType { get; init; } = default!;
+        public DateTimeOffset Now { get; init; } = DateTimeOffset.UtcNow;
+    }
+
+}

backend/IM_API/Tools/RedisKeys.cs

@@ -2,10 +2,13 @@
 {
     public static class RedisKeys
     {
-        public static string GetUserinfoKey(string userId) => $"user::uinfo::{userId}";
-        public static string GetUserinfoKeyByUsername(string username) => $"user::uinfobyid::{username}";
-        public static string GetSequenceIdKey(string streamKey) => $"chat::seq::{streamKey}";
-        public static string GetSequenceIdLockKey(string streamKey) => $"lock::seq::{streamKey}";
-        public static string GetConnectionIdKey(string userId) => $"signalr::user::con::{userId}";
+        public static string GetUserinfoKey(string userId) => $"user:uinfo:{userId}";
+        public static string GetUserinfoKeyByUsername(string username) => $"user:uinfobyid:{username}";
+        public static string GetSequenceIdKey(string streamKey) => $"chat:seq:{streamKey}";
+        public static string GetSequenceIdLockKey(string streamKey) => $"lock:seq:{streamKey}";
+        public static string GetConnectionIdKey(string userId) => $"signalr:user:con:{userId}";
+
+        public static string GetUploadPartKey(Guid taskId) => $"upload:task:{taskId}:parts";
+        public static string MergeStatus(Guid taskId) => $"upload:task:{taskId}:merge";
     }
 }

backend/IM_API/Tools/UrlTools.cs

@@ -0,0 +1,64 @@
+using SixLabors.ImageSharp;
+using System.Text.Json;
+using System.Text.Json.Nodes;
+
+namespace IM_API.Tools
+{
+    public static class UrlTools
+    {
+        public static string GetFullUrl(string objectName, string provider, string? baseUrl)
+        {
+            return provider switch
+            {
+                "Local" => $"{baseUrl}/uploads/files/{objectName}",
+                _ => "http://baidu.com",
+            };
+        }
+
+        public static async Task<(int width, int height)> GetImageWH(string url)
+        {
+            using var httpClient = new HttpClient();
+            var stream = await httpClient.GetStreamAsync(url);
+            var info = await Image.IdentifyAsync(stream);
+            return (info.Width, info.Height);
+        }
+
+        public static string ProcessMessageUrl(string contentJson, string? localBaseUrl)
+        {
+            // 1. 解析 JSON 文档（比反序列化快得多）
+            using var doc = JsonDocument.Parse(contentJson);
+            var root = doc.RootElement;
+
+            // 2. 获取 Provider 字段
+            string provider = root.GetProperty("provider").GetString();
+
+            // 3. 根据 Provider 决定前缀
+            string prefix = GetFullUrl("", provider, localBaseUrl);
+
+            // 4. 重新组装（如果只是为了给前端看，建议直接返回带前缀的对象或字符串）
+            // 这里推荐用 JsonNode 方便修改并返回字符串
+            var node = JsonNode.Parse(contentJson);
+            node["url"] = $"{prefix}{node["url"]}";
+            node["thumb"] = $"{prefix}{node["thumb"]}";
+
+            return node.ToJsonString();
+        }
+        public static Stream Base64ToStream(string base64String)
+        {
+            if (string.IsNullOrEmpty(base64String))
+                throw new ArgumentNullException(nameof(base64String));
+
+            // 1. 自动处理可能存在的 Base64 Data URL 前缀
+            string base64Data = base64String.Contains(",")
+                ? base64String.Split(',')[1]
+                : base64String;
+
+            // 2. 解码为字节数组
+            byte[] bytes = Convert.FromBase64String(base64Data);
+
+            // 3. 包装进 MemoryStream
+            // 注意：这里直接把 Position 设为 0，符合“方法a”产生即用的原则
+            return new MemoryStream(bytes);
+        }
+    }
+}