新增下载人查询接口，并把管理员判定收敛到服务端

- Gallery 增加 downloaderName，仅在管理员查询任务列表时填充；普通用户
  既不获取也不下发他人身份
- 新增 GET /GalleryManage/downloader?gid=&AuthCode=，按 gid 返回实际下载人
  昵称，非管理员一律拒绝
- /validate 下发 isAdmin，前端不再各自硬编码 userId === 3
- 管理员判定统一走 UserService.ADMIN_USER_ID
- 补充列表填充、按 gid 查询的权限与缺任务分支测试

src/main/java/com/lion/lionwebsite/Controller/GalleryManageController.java

@@ -67,6 +67,14 @@ public class GalleryManageController {
         return galleryManageService.deleteGalleryByGid(gid, AuthCode);
     }
 
+    /** 按 gid 查实际下载人昵称，仅管理员可用。 */
+    @GetMapping("/downloader")
+    public String selectDownloader(Integer gid, String AuthCode){
+        if(gid == null)
+            return Response._failure("参数不全");
+        return galleryManageService.selectDownloaderByGid(gid, AuthCode);
+    }
+
 
     @PostMapping("/collect")
     public String collectGallery(Integer gid, String AuthCode){

src/main/java/com/lion/lionwebsite/Controller/PublicController.java

@@ -6,6 +6,7 @@ import com.lion.lionwebsite.Service.PublicService;
 import com.lion.lionwebsite.Service.QueryService;
 import com.lion.lionwebsite.Service.RemoteService;
 import com.lion.lionwebsite.Service.SubService;
+import com.lion.lionwebsite.Service.UserService;
 import com.lion.lionwebsite.Util.Response;
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
@@ -82,9 +83,12 @@ public class PublicController {
         Response response = Response.generateResponse();
         User user = publicService.getUserId(AuthCode);
         String isAvailable = remoteService.isDead() ? "false": "true";
+        // 管理员标记随登录一起下发，前端据此决定是否显示下载人信息与筛选。
+        String isAdmin = user.getId() == UserService.ADMIN_USER_ID ? "true" : "false";
         response.success(String.format("{\"userId\": %d, " +
                                         "\"username\": \"%s\", " +
-                                        "\"isAvailable\": %s}", user.getId(), user.getUsername(), isAvailable));
+                                        "\"isAvailable\": %s, " +
+                                        "\"isAdmin\": %s}", user.getId(), user.getUsername(), isAvailable, isAdmin));
         return response.toJSONString();
     }
 

src/main/java/com/lion/lionwebsite/Dao/normal/UserMapper.java

@@ -14,6 +14,9 @@ public interface UserMapper {
     @Select("select * from User where username=#{username}")
     User selectUserByUsername(String username);
 
+    @Select("select * from User where id=#{id}")
+    User selectUserById(int id);
+
     @Select("select AuthCode from User")
     String[] selectAllAuthCode();
 

src/main/java/com/lion/lionwebsite/Domain/Gallery.java

@@ -48,6 +48,11 @@ public class Gallery {
     @JsonProperty("downloader")
     private int downloader;                              //下载人
 
+    /** 下载人昵称。仅管理员查询时填充，普通用户拿不到，避免暴露他人信息。 */
+    @JsonProperty("downloaderName")
+    @JsonInclude(JsonInclude.Include.NON_EMPTY)
+    private String downloaderName;
+
     @JsonProperty("collector")
     @JsonInclude(JsonInclude.Include.NON_EMPTY)
     private String collector;                               //收藏人

src/main/java/com/lion/lionwebsite/Service/GalleryManageService.java

@@ -13,6 +13,7 @@ import com.lion.lionwebsite.Util.GalleryUtil;
 import com.lion.lionwebsite.Util.Response;
 import tools.jackson.core.JacksonException;
 import tools.jackson.databind.ObjectMapper;
+import tools.jackson.databind.node.ObjectNode;
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
 import lombok.Data;
@@ -254,10 +255,56 @@ public class GalleryManageService {
                 }
             }
 
+        // 下载人昵称只对管理员下发；一次建表避免逐条查询。
+        if (userId == UserService.ADMIN_USER_ID)
+            fillDownloaderNames(galleries);
+
         response.success(new ObjectMapper().valueToTree(galleries).toString());
         return response.toJSONString();
     }
 
+    /** 给任务列表补上下载人昵称，找不到用户时保留空值而不是报错。 */
+    private void fillDownloaderNames(Gallery[] galleries) {
+        User[] users = userMapper.selectAllUser();
+        Map<Integer, String> names = new HashMap<>();
+        if (users != null)
+            for (User user : users)
+                names.put(user.getId(), user.getUsername());
+
+        for (Gallery gallery : galleries)
+            gallery.setDownloaderName(names.get(gallery.getDownloader()));
+    }
+
+    /**
+     * 查询某个任务的实际下载人昵称。
+     * 只有管理员可调用，普通用户一律拒绝，避免暴露他人身份。
+     *
+     * @param gid      任务 gid
+     * @param AuthCode 调用方授权码
+     */
+    public String selectDownloaderByGid(int gid, String AuthCode) {
+        Response response = Response.generateResponse();
+        User requester = userMapper.selectUserByAuthCode(AuthCode);
+        if (requester == null || requester.getId() != UserService.ADMIN_USER_ID) {
+            response.failure("无权查看下载人");
+            return response.toJSONString();
+        }
+
+        Gallery gallery = galleryMapper.selectGalleryByGid(gid);
+        if (gallery == null) {
+            response.failure("任务不存在");
+            return response.toJSONString();
+        }
+
+        User downloader = userMapper.selectUserById(gallery.getDownloader());
+        ObjectNode node = objectMapper.createObjectNode();
+        node.put("gid", gid);
+        node.put("downloader", gallery.getDownloader());
+        node.put("downloaderName", downloader == null ? "" : downloader.getUsername());
+        response.success(node);
+        return response.toJSONString();
+    }
+
     /**
      * 通过图片名查询图片
      *

src/main/java/com/lion/lionwebsite/Service/UserService.java

@@ -135,4 +135,18 @@ public class UserService{
     public int getUserId(String AuthCode){
         return userMapper.selectUserByAuthCode(AuthCode).getId();
     }
+
+    /**
+     * 管理员判定。项目没有角色表，历史上以 id=3（狮子）作为管理员，
+     * 前端也是用 userId === 3 判断；这里把这个约定收敛到一处，
+     * 权限相关的服务端校验统一走它。
+     */
+    public static final int ADMIN_USER_ID = 3;
+
+    public boolean isAdmin(String AuthCode){
+        if(AuthCode == null)
+            return false;
+        User user = userMapper.selectUserByAuthCode(AuthCode);
+        return user != null && user.getId() == ADMIN_USER_ID;
+    }
 }