feat(knowledge): 添加知识条目导出功能和文件上传支持

- 在 KnowledgeItemApplicationService 中新增 exportKnowledgeItems 方法实现知识条目导出
- 添加 export 相关常量配置包括文件名格式、内容类型等
- 在 KnowledgeItemRepository 中新增 findAllBySetId 查询方法
- 在 KnowledgeItemController 中新增 export 接口端点
- 在 KnowledgeItemEditor 组件中添加文件上传功能支持 txt/md/markdown 格式
- 在 KnowledgeSetDetail 页面中添加导出按钮并集成导出 API
- 更新前端 API 文件添加 exportKnowledgeItemsUsingGet 方法
- 配置文件上传验证和自动填充标题内容逻辑

backend/services/data-management-service/src/main/java/com/datamate/datamanagement/application/KnowledgeItemApplicationService.java

@@ -27,10 +27,13 @@ import com.datamate.datamanagement.interfaces.dto.ImportKnowledgeItemsRequest;
 import com.datamate.datamanagement.interfaces.dto.KnowledgeItemPagingQuery;
 import com.datamate.datamanagement.interfaces.dto.KnowledgeItemResponse;
 import com.datamate.datamanagement.interfaces.dto.UpdateKnowledgeItemRequest;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import jakarta.servlet.http.HttpServletResponse;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.commons.collections4.CollectionUtils;
 import org.apache.commons.lang3.StringUtils;
+import org.springframework.http.HttpHeaders;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
@@ -40,6 +43,8 @@ import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.time.format.DateTimeFormatter;
 import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
@@ -56,6 +61,10 @@ import java.util.UUID;
 @RequiredArgsConstructor
 public class KnowledgeItemApplicationService {
     private static final Set<String> SUPPORTED_TEXT_EXTENSIONS = Set.of("txt", "md", "markdown");
+    private static final DateTimeFormatter EXPORT_TIME_FORMATTER = DateTimeFormatter.ofPattern("yyyyMMddHHmmss");
+    private static final String EXPORT_FILE_PREFIX = "knowledge_set_";
+    private static final String EXPORT_FILE_SUFFIX = ".json";
+    private static final String EXPORT_CONTENT_TYPE = "application/json";
 
     private final KnowledgeItemRepository knowledgeItemRepository;
     private final KnowledgeSetRepository knowledgeSetRepository;
@@ -214,12 +223,37 @@ public class KnowledgeItemApplicationService {
         return items;
     }
 
+    @Transactional(readOnly = true)
+    public void exportKnowledgeItems(String setId, HttpServletResponse response) {
+        BusinessAssert.notNull(response, CommonErrorCode.PARAM_ERROR);
+        KnowledgeSet knowledgeSet = requireKnowledgeSet(setId);
+        List<KnowledgeItem> items = knowledgeItemRepository.findAllBySetId(setId);
+        List<KnowledgeItemResponse> responses = KnowledgeConverter.INSTANCE.convertItemResponses(items);
+
+        response.setContentType(EXPORT_CONTENT_TYPE);
+        response.setCharacterEncoding(StandardCharsets.UTF_8.name());
+        response.setHeader(HttpHeaders.CONTENT_DISPOSITION,
+            "attachment; filename=\"" + buildExportFileName(knowledgeSet.getId()) + "\"");
+
+        ObjectMapper objectMapper = new ObjectMapper();
+        try {
+            objectMapper.writeValue(response.getOutputStream(), responses);
+        } catch (IOException e) {
+            log.error("export knowledge items error, setId: {}", setId, e);
+            throw BusinessException.of(SystemErrorCode.FILE_SYSTEM_ERROR);
+        }
+    }
+
     private KnowledgeSet requireKnowledgeSet(String setId) {
         KnowledgeSet knowledgeSet = knowledgeSetRepository.getById(setId);
         BusinessAssert.notNull(knowledgeSet, DataManagementErrorCode.KNOWLEDGE_SET_NOT_FOUND);
         return knowledgeSet;
     }
 
+    private String buildExportFileName(String setId) {
+        return EXPORT_FILE_PREFIX + setId + "_" + LocalDateTime.now().format(EXPORT_TIME_FORMATTER) + EXPORT_FILE_SUFFIX;
+    }
+
     private KnowledgeContentType resolveContentType(DatasetFile datasetFile) {
         String extension = getFileExtension(datasetFile);
         if (StringUtils.isBlank(extension)) {

backend/services/data-management-service/src/main/java/com/datamate/datamanagement/infrastructure/persistence/repository/KnowledgeItemRepository.java

@@ -4,6 +4,7 @@ import com.baomidou.mybatisplus.core.metadata.IPage;
 import com.baomidou.mybatisplus.extension.repository.IRepository;
 import com.datamate.datamanagement.domain.model.knowledge.KnowledgeItem;
 import com.datamate.datamanagement.interfaces.dto.KnowledgeItemPagingQuery;
+import java.util.List;
 
 /**
  * 知识条目仓储接口
@@ -12,4 +13,6 @@ public interface KnowledgeItemRepository extends IRepository<KnowledgeItem> {
     IPage<KnowledgeItem> findByCriteria(IPage<KnowledgeItem> page, KnowledgeItemPagingQuery query);
 
     long countBySetId(String setId);
+
+    List<KnowledgeItem> findAllBySetId(String setId);
 }

backend/services/data-management-service/src/main/java/com/datamate/datamanagement/infrastructure/persistence/repository/impl/KnowledgeItemRepositoryImpl.java

@@ -11,6 +11,8 @@ import lombok.RequiredArgsConstructor;
 import org.apache.commons.lang3.StringUtils;
 import org.springframework.stereotype.Repository;
 
+import java.util.List;
+
 /**
  * 知识条目仓储实现类
  */
@@ -59,4 +61,11 @@ public class KnowledgeItemRepositoryImpl extends CrudRepository<KnowledgeItemMap
         return knowledgeItemMapper.selectCount(new LambdaQueryWrapper<KnowledgeItem>()
             .eq(KnowledgeItem::getSetId, setId));
     }
+
+    @Override
+    public List<KnowledgeItem> findAllBySetId(String setId) {
+        return knowledgeItemMapper.selectList(new LambdaQueryWrapper<KnowledgeItem>()
+            .eq(KnowledgeItem::getSetId, setId)
+            .orderByDesc(KnowledgeItem::getCreatedAt));
+    }
 }

backend/services/data-management-service/src/main/java/com/datamate/datamanagement/interfaces/rest/KnowledgeItemController.java

@@ -1,5 +1,6 @@
 package com.datamate.datamanagement.interfaces.rest;
 
+import com.datamate.common.infrastructure.common.IgnoreResponseWrap;
 import com.datamate.common.interfaces.PagedResponse;
 import com.datamate.datamanagement.application.KnowledgeItemApplicationService;
 import com.datamate.datamanagement.domain.model.knowledge.KnowledgeItem;
@@ -9,6 +10,7 @@ import com.datamate.datamanagement.interfaces.dto.ImportKnowledgeItemsRequest;
 import com.datamate.datamanagement.interfaces.dto.KnowledgeItemPagingQuery;
 import com.datamate.datamanagement.interfaces.dto.KnowledgeItemResponse;
 import com.datamate.datamanagement.interfaces.dto.UpdateKnowledgeItemRequest;
+import jakarta.servlet.http.HttpServletResponse;
 import jakarta.validation.Valid;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
@@ -46,6 +48,12 @@ public class KnowledgeItemController {
         return KnowledgeConverter.INSTANCE.convertItemResponses(items);
     }
 
+    @IgnoreResponseWrap
+    @GetMapping("/export")
+    public void exportKnowledgeItems(@PathVariable("setId") String setId, HttpServletResponse response) {
+        knowledgeItemApplicationService.exportKnowledgeItems(setId, response);
+    }
+
     @GetMapping("/{itemId}")
     public KnowledgeItemResponse getKnowledgeItemById(@PathVariable("setId") String setId,
                                                       @PathVariable("itemId") String itemId) {