OSS 结果文件下载分流：新增 aiimage.oss.download-endpoint 配置，result/ 前缀对象生成独立下载域名直链（默认未配置时回退原行为）

backend-java/src/main/java/com/nanri/aiimage/config/OssProperties.java

@@ -9,6 +9,7 @@ public class OssProperties {
     private String region;
     private String endpoint;
     private String publicEndpoint;
+    private String downloadEndpoint;
     private String bucket;
     private String imageVideoBucket;
     private String digitalHumanBucket;

backend-java/src/main/java/com/nanri/aiimage/modules/file/service/oss/OssStorageService.java

@@ -302,8 +302,12 @@ public class OssStorageService {
     }
 
     public String generateFreshDownloadUrl(String value) {
+        StorageLocation location = resolveStorageLocation(value);
+        if (location == null) {
             return getPublicUrl(value);
         }
+        return buildDownloadPublicUrl(location.objectKey(), location.bucket());
+    }
 
     private void uploadFile(File file, String bucket, String objectKey) {
         if (file == null || !file.isFile()) {
@@ -321,6 +325,22 @@ public class OssStorageService {
     }
 
     private String getPublicUrl(String objectKey, String bucket) {
+        return buildPublicUrl(trimTrailingSlash(publicEndpoint()), objectKey, bucket);
+    }
+
+    /**
+     * 结果文件（objectKey 以 {@code result/} 开头）的下载直链。
+     * 配置了 download-endpoint 时走下载域名（独立出口/缓存节点），否则回退到公开 endpoint。
+     */
+    private String buildDownloadPublicUrl(String objectKey, String bucket) {
+        String base = downloadEndpoint();
+        if (base == null || objectKey == null || !objectKey.startsWith("result/")) {
+            return getPublicUrl(objectKey, bucket);
+        }
+        return buildPublicUrl(base, objectKey, bucket);
+    }
+
+    private String buildPublicUrl(String baseUrl, String objectKey, String bucket) {
         String encodedPath;
         try {
             encodedPath = new URI(null, null, "/" + bucket + "/" + trimLeadingSlash(objectKey), null)
@@ -328,7 +348,7 @@ public class OssStorageService {
         } catch (Exception ex) {
             encodedPath = "/" + bucket + "/" + trimLeadingSlash(objectKey).replace(" ", "%20");
         }
-        return trimTrailingSlash(publicEndpoint()) + encodedPath;
+        return trimTrailingSlash(baseUrl) + encodedPath;
     }
 
     private StorageLocation resolveStorageLocation(String value) {
@@ -488,6 +508,14 @@ public class OssStorageService {
         return withScheme(firstNonBlank(ossProperties.getPublicEndpoint(), ossProperties.getEndpoint()));
     }
 
+    private String downloadEndpoint() {
+        String configured = ossProperties.getDownloadEndpoint();
+        if (configured == null || configured.isBlank()) {
+            return null;
+        }
+        return withScheme(configured.trim());
+    }
+
     private String resultObjectKey(File file, String moduleType) {
         return String.format("result/%s/%s/%s", normalizeModuleType(moduleType), UUID.randomUUID(), file.getName());
     }

backend-java/src/main/resources/application.yml

@@ -97,6 +97,7 @@ aiimage:
     region: ${AIIMAGE_OSS_REGION:us-east-1}
     endpoint: ${AIIMAGE_OSS_ENDPOINT:https://oss.aishufu.top}
     public-endpoint: ${AIIMAGE_OSS_PUBLIC_ENDPOINT:https://oss.aishufu.top}
+    download-endpoint: ${AIIMAGE_OSS_DOWNLOAD_ENDPOINT:}
     bucket: ${AIIMAGE_OSS_BUCKET:nanri-ai-images}
     image-video-bucket: ${AIIMAGE_IMAGE_VIDEO_OSS_BUCKET:shufu-video}
     digital-human-bucket: ${AIIMAGE_DIGITAL_HUMAN_OSS_BUCKET:nanri-ai-digital-human}

backend-java/src/test/java/com/nanri/aiimage/modules/file/service/oss/OssStorageServiceTest.java

@@ -12,10 +12,11 @@ import static org.junit.jupiter.api.Assertions.assertNull;
 class OssStorageServiceTest {
 
     private OssStorageService storageService;
+    private OssProperties properties;
 
     @BeforeEach
     void setUp() {
-        OssProperties properties = new OssProperties();
+        properties = new OssProperties();
         properties.setEndpoint("https://oss.aishufu.top");
         properties.setPublicEndpoint("https://oss.aishufu.top");
         properties.setBucket("nanri-ai-images");
@@ -93,4 +94,37 @@ class OssStorageServiceTest {
         assertNull(storageService.normalizeManagedPublicUrl(null));
         assertEquals("   ", storageService.normalizeManagedPublicUrl("   "));
     }
+
+    @Test
+    void resultFilesUseDownloadEndpointWhenConfigured() {
+        properties().setDownloadEndpoint("https://download.aishufu.top");
+        assertEquals(
+                "https://download.aishufu.top/nanri-ai-images/result/similar_asin/1/%E9%87%8D%E6%96%B0-result.xlsx",
+                storageService.generateFreshDownloadUrl("result/similar_asin/1/重新-result.xlsx"));
+        assertEquals(
+                "https://download.aishufu.top/nanri-ai-images/result/similar_asin/1/re.xlsx",
+                storageService.generateFreshDownloadUrl("https://oss.aishufu.top/nanri-ai-images/result/similar_asin/1/re.xlsx"));
+    }
+
+    @Test
+    void nonResultAndUnmanagedValuesKeepPublicEndpoint() {
+        properties().setDownloadEndpoint("https://download.aishufu.top");
+        assertEquals(
+                "https://oss.aishufu.top/nanri-ai-images/supply_images/main.jpg",
+                storageService.generateFreshDownloadUrl("supply_images/main.jpg"));
+        assertEquals(
+                "https://download.aishufu.top/shufu-video/result/image_video/demo.mp4",
+                storageService.generateFreshDownloadUrl("shufu-video/result/image_video/demo.mp4"));
+    }
+
+    @Test
+    void downloadEndpointDisabledFallsBackToPublicEndpoint() {
+        assertEquals(
+                "https://oss.aishufu.top/nanri-ai-images/result/similar_asin/1/re.xlsx",
+                storageService.generateFreshDownloadUrl("result/similar_asin/1/re.xlsx"));
+    }
+
+    private OssProperties properties() {
+        return properties;
+    }
 }