feat(file): 增强文件下载功能与实体定义

- 使用SysFile.Fields常量替代硬编码字符串字段名
- 增加文件不存在时的日志警告与提前返回处理
- 为SysFile实体添加FieldNameConstants注解与Serial标记
- 优化文件下载响应头设置与异常处理逻辑

pigx-upms/pigx-upms-api/src/main/java/com/pig4cloud/pigx/admin/api/entity/SysFile.java

@@ -23,7 +23,9 @@ import com.pig4cloud.pigx.common.core.util.TenantTable;
 import io.swagger.v3.oas.annotations.media.Schema;
 import lombok.Data;
 import lombok.EqualsAndHashCode;
+import lombok.experimental.FieldNameConstants;
 
+import java.io.Serial;
 import java.time.LocalDateTime;
 
 /**
@@ -34,10 +36,12 @@ import java.time.LocalDateTime;
  */
 @Data
 @TenantTable
+@FieldNameConstants
 @Schema(description = "文件")
 @EqualsAndHashCode(callSuper = true)
 public class SysFile extends Model<SysFile> {
 
+    @Serial
     private static final long serialVersionUID = 1L;
 
     /**

pigx-upms/pigx-upms-biz/src/main/java/com/pig4cloud/pigx/admin/service/impl/SysFileServiceImpl.java

@@ -118,16 +118,21 @@ public class SysFileServiceImpl extends ServiceImpl<SysFileMapper, SysFile> impl
         TenantContextHolder.setTenantSkip();
         // 增加历史数据兼容 /admin/sys-file/local?fileName=xxx.png
         Map<String, String> stringMap = HttpUtil.decodeParamMap(fileName, Charset.defaultCharset());
-        String urlFileName = MapUtil.getStr(stringMap, "fileName");
+        String urlFileName = MapUtil.getStr(stringMap, SysFile.Fields.fileName);
         if (StrUtil.isNotBlank(urlFileName)) {
             fileName = urlFileName;
         }
 
         SysFile sysFile = baseMapper.selectOne(Wrappers.<SysFile>lambdaQuery().eq(SysFile::getFileName, fileName), false);
+        if (Objects.isNull(sysFile)) {
+            log.warn("文件不存在: {}", fileName);
+            return;
+        }
+
         try (S3Object s3Object = fileTemplate.getObject(sysFile.getBucketName(), sysFile.getDir(), fileName)) {
             response.setContentType("application/octet-stream; charset=UTF-8");
             // 文件唯一hash
-            response.addHeader("Hash", sysFile.getHash());
+            response.addHeader(SysFile.Fields.hash, sysFile.getHash());
             response.addHeader(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=" + URLUtil.encode(sysFile.getOriginal()));
             IoUtil.copy(s3Object.getObjectContent(), response.getOutputStream());
         } catch (Exception e) {