feat(aiot): 截图持久化 — cos_key 存入 DB，proxyImage 支持 DB 兜底

- 新建 wvp_ai_camera_snapshot 表（camera_code → cos_key 映射）
- 新建 AiCameraSnapshotMapper（getCosKey / upsert）
- AiScreenshotServiceImpl: handleCallback 成功后将 cos_key 写入 DB
- AiScreenshotServiceImpl: proxyScreenshotImage 增加 DB 兜底路径
  Redis 缓存(5min) → DB(永久) → CosUtil 生成 presigned URL → 下载
- AiRoiController: Cache-Control 从 60s 增大到 300s

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/main/java/com/genersoft/iot/vmp/aiot/controller/AiRoiController.java

@@ -124,7 +124,7 @@ public class AiRoiController {
         }
         return ResponseEntity.ok()
                 .contentType(MediaType.IMAGE_JPEG)
-                .header("Cache-Control", "max-age=60")
+                .header("Cache-Control", "public, max-age=300")
                 .body(image);
     }
 }

src/main/java/com/genersoft/iot/vmp/aiot/dao/AiCameraSnapshotMapper.java

@@ -0,0 +1,15 @@
+package com.genersoft.iot.vmp.aiot.dao;
+
+import org.apache.ibatis.annotations.*;
+
+@Mapper
+public interface AiCameraSnapshotMapper {
+
+    @Select("SELECT cos_key FROM wvp_ai_camera_snapshot WHERE camera_code = #{cameraCode}")
+    String getCosKey(@Param("cameraCode") String cameraCode);
+
+    @Insert("INSERT INTO wvp_ai_camera_snapshot (camera_code, cos_key) " +
+            "VALUES (#{cameraCode}, #{cosKey}) " +
+            "ON DUPLICATE KEY UPDATE cos_key = #{cosKey}, updated_at = NOW()")
+    int upsert(@Param("cameraCode") String cameraCode, @Param("cosKey") String cosKey);
+}

src/main/java/com/genersoft/iot/vmp/aiot/service/impl/AiScreenshotServiceImpl.java

@@ -2,7 +2,9 @@ package com.genersoft.iot.vmp.aiot.service.impl;
 
 import com.alibaba.fastjson2.JSON;
 import com.alibaba.fastjson2.JSONObject;
+import com.genersoft.iot.vmp.aiot.dao.AiCameraSnapshotMapper;
 import com.genersoft.iot.vmp.aiot.service.IAiScreenshotService;
+import com.genersoft.iot.vmp.aiot.util.CosUtil;
 import com.genersoft.iot.vmp.streamProxy.bean.StreamProxy;
 import com.genersoft.iot.vmp.streamProxy.dao.StreamProxyMapper;
 import lombok.extern.slf4j.Slf4j;
@@ -41,12 +43,21 @@ public class AiScreenshotServiceImpl implements IAiScreenshotService {
     /** 等待 Edge 回调的 pending 请求表 */
     private final ConcurrentHashMap<String, CompletableFuture<Map<String, Object>>> pendingRequests = new ConcurrentHashMap<>();
 
+    /** requestId → cosPath 映射，截图回调成功后持久化到 DB */
+    private final ConcurrentHashMap<String, String> pendingCosKeys = new ConcurrentHashMap<>();
+
     @Autowired
     private StringRedisTemplate stringRedisTemplate;
 
     @Autowired
     private StreamProxyMapper streamProxyMapper;
 
+    @Autowired
+    private AiCameraSnapshotMapper snapshotMapper;
+
+    @Autowired
+    private CosUtil cosUtil;
+
     @Value("${ai.screenshot.callback-url:}")
     private String callbackUrl;
 
@@ -100,6 +111,7 @@ public class AiScreenshotServiceImpl implements IAiScreenshotService {
         try {
             MapRecord<String, String, String> record = MapRecord.create(SNAP_REQUEST_STREAM, fields);
             RecordId recordId = stringRedisTemplate.opsForStream().add(record);
+            pendingCosKeys.put(requestId, cosPath);
             log.info("[AI截图] 发送截图请求: requestId={}, cameraCode={}, streamId={}", requestId, cameraCode, recordId);
         } catch (Exception e) {
             log.error("[AI截图] 发送截图请求失败: {}", e.getMessage());
@@ -182,6 +194,19 @@ public class AiScreenshotServiceImpl implements IAiScreenshotService {
         if ("ok".equals(status) && cameraCode != null) {
             String url = (String) data.get("url");
             writeCache(cameraCode, url);
+
+            // 持久化 cos_key 到 DB（永不过期，供后续直接读取）
+            String cosKey = pendingCosKeys.remove(requestId);
+            if (cosKey != null) {
+                try {
+                    snapshotMapper.upsert(cameraCode, cosKey);
+                    log.info("[AI截图] cos_key 已持久化: cameraCode={}, cosKey={}", cameraCode, cosKey);
+                } catch (Exception e) {
+                    log.error("[AI截图] 持久化 cos_key 失败: cameraCode={}, error={}", cameraCode, e.getMessage());
+                }
+            }
+        } else {
+            pendingCosKeys.remove(requestId);
         }
 
         CompletableFuture<Map<String, Object>> future = pendingRequests.get(requestId);
@@ -218,27 +243,58 @@ public class AiScreenshotServiceImpl implements IAiScreenshotService {
 
     @Override
     public byte[] proxyScreenshotImage(String cameraCode) {
+        // 1. 先查 Redis 缓存中的 presigned URL（5分钟有效）
         String cacheJson = stringRedisTemplate.opsForValue().get(SNAP_CACHE_KEY_PREFIX + cameraCode);
-        if (cacheJson == null) {
-            log.warn("[AI截图] 代理图片: 缓存不存在 cameraCode={}", cameraCode);
+        if (cacheJson != null) {
+            try {
+                JSONObject cached = JSON.parseObject(cacheJson);
+                String cosUrl = cached.getString("url");
+                if (cosUrl != null && !cosUrl.isEmpty()) {
+                    RestTemplate restTemplate = new RestTemplate();
+                    byte[] bytes = restTemplate.getForObject(URI.create(cosUrl), byte[].class);
+                    if (bytes != null && bytes.length > 0) {
+                        log.debug("[AI截图] 代理图片(Redis缓存): cameraCode={}, size={}", cameraCode, bytes.length);
+                        return bytes;
+                    }
+                }
+            } catch (Exception e) {
+                log.warn("[AI截图] Redis 缓存 URL 下载失败，尝试 DB: {}", e.getMessage());
+            }
+        }
+
+        // 2. 查 DB 持久化的 cos_key（永不过期）
+        String cosKey = snapshotMapper.getCosKey(cameraCode);
+        if (cosKey == null) {
+            log.warn("[AI截图] 代理图片: 无缓存也无持久化记录 cameraCode={}", cameraCode);
+            return null;
+        }
+
+        // 3. 通过 CosUtil 直接生成 presigned URL（无需调 FastAPI）
+        if (!cosUtil.isAvailable()) {
+            log.warn("[AI截图] COS 客户端未初始化，无法生成 presigned URL");
+            return null;
+        }
+
+        String presignedUrl = cosUtil.generatePresignedUrl(cosKey);
+        if (presignedUrl == null) {
+            log.error("[AI截图] 生成 presigned URL 失败: cosKey={}", cosKey);
             return null;
         }
 
         try {
-            JSONObject cached = JSON.parseObject(cacheJson);
-            String cosUrl = cached.getString("url");
-            if (cosUrl == null || cosUrl.isEmpty()) {
-                log.warn("[AI截图] 代理图片: 缓存中无 URL cameraCode={}", cameraCode);
-                return null;
-            }
-
-            // 使用 URI.create 避免 RestTemplate 对已编码的预签名 URL 做二次编码
+            // 4. 下载图片
             RestTemplate restTemplate = new RestTemplate();
-            byte[] imageBytes = restTemplate.getForObject(URI.create(cosUrl), byte[].class);
-            log.debug("[AI截图] 代理图片成功: cameraCode={}, size={}", cameraCode, imageBytes != null ? imageBytes.length : 0);
+            byte[] imageBytes = restTemplate.getForObject(URI.create(presignedUrl), byte[].class);
+
+            // 5. 更新 Redis 缓存（加速后续请求）
+            if (imageBytes != null && imageBytes.length > 0) {
+                writeCache(cameraCode, presignedUrl);
+                log.debug("[AI截图] 代理图片(DB→COS): cameraCode={}, size={}", cameraCode, imageBytes.length);
+            }
             return imageBytes;
         } catch (Exception e) {
-            log.error("[AI截图] 代理下载图片失败: cameraCode={}, error={}", cameraCode, e.getMessage());
+            log.error("[AI截图] 通过 DB cos_key 下载图片失败: cameraCode={}, cosKey={}, error={}",
+                    cameraCode, cosKey, e.getMessage());
             return null;
         }
     }