feat(knowledge-base): 添加知识库统计功能

- 后端服务新增 KnowledgeBaseStatisticsResp 和 RagFileStatistics 数据传输对象
- 在 KnowledgeBaseService 中实现 getStatistics 方法提供统计信息查询
- 为 RagFileRepository 添加 getStatistics 接口及其实现
- 通过 MyBatis Mapper 实现数据库层面的统计查询功能
- 在 KnowledgeBaseController 中暴露 /statistics 接口供前端调用
- 前端页面集成统计卡片组件展示知识库、文件数量及总大小信息
- 实现前后端数据同步机制确保统计数据实时更新

frontend/src/pages/KnowledgeBase/Home/KnowledgeBasePage.tsx

@@ -1,23 +1,48 @@
-import { useState } from "react";
-import { Card, Button, Table, Tooltip, message } from "antd";
+import { useCallback, useEffect, useState } from "react";
+import { Card, Button, Table, Tooltip, message, Statistic } from "antd";
 import { DeleteOutlined, EditOutlined } from "@ant-design/icons";
 import { SearchControls } from "@/components/SearchControls";
 import { useNavigate } from "react-router";
 import CardView from "@/components/CardView";
 import {
   deleteKnowledgeBaseByIdUsingDelete,
+  getKnowledgeBaseStatisticsUsingGet,
   queryKnowledgeBasesUsingPost,
 } from "../knowledge-base.api";
 import useFetchData from "@/hooks/useFetchData";
-import { KnowledgeBaseItem } from "../knowledge-base.model";
+import { KnowledgeBaseItem, KnowledgeBaseStatistics } from "../knowledge-base.model";
 import CreateKnowledgeBase from "../components/CreateKnowledgeBase";
 import { mapKnowledgeBase } from "../knowledge-base.const";
+import { formatBytes } from "@/utils/unit";
+
+type StatisticsItem = {
+  title: string;
+  value: number | string;
+};
+
+const DEFAULT_STATISTICS: StatisticsItem[] = [
+  {
+    title: "知识库总数",
+    value: 0,
+  },
+  {
+    title: "文件总数",
+    value: 0,
+  },
+  {
+    title: "总大小",
+    value: "0 B",
+  },
+];
 
 export default function KnowledgeBasePage() {
   const navigate = useNavigate();
   const [viewMode, setViewMode] = useState<"card" | "list">("card");
   const [isEdit, setIsEdit] = useState(false);
   const [currentKB, setCurrentKB] = useState<KnowledgeBaseItem | null>(null);
+  const [statisticsData, setStatisticsData] = useState<StatisticsItem[]>(
+    DEFAULT_STATISTICS
+  );
   const {
     loading,
     tableData,
@@ -32,11 +57,43 @@ export default function KnowledgeBasePage() {
     (kb) => mapKnowledgeBase(kb, false) // 在首页不显示索引模型和文本理解模型字段
   );
 
+  const fetchStatistics = useCallback(async () => {
+    try {
+      const { data } = await getKnowledgeBaseStatisticsUsingGet();
+      const stats = data as KnowledgeBaseStatistics | undefined;
+      setStatisticsData([
+        {
+          title: "知识库总数",
+          value: stats?.totalKnowledgeBases ?? 0,
+        },
+        {
+          title: "文件总数",
+          value: stats?.totalFiles ?? 0,
+        },
+        {
+          title: "总大小",
+          value: formatBytes(stats?.totalSize ?? 0),
+        },
+      ]);
+    } catch {
+      message.error("统计数据加载失败");
+      setStatisticsData(DEFAULT_STATISTICS);
+    }
+  }, []);
+
+  const refreshAll = useCallback(async () => {
+    await Promise.all([fetchData(), fetchStatistics()]);
+  }, [fetchData, fetchStatistics]);
+
+  useEffect(() => {
+    fetchStatistics();
+  }, [fetchStatistics]);
+
   const handleDeleteKB = async (kb: KnowledgeBaseItem) => {
     try {
       await deleteKnowledgeBaseByIdUsingDelete(kb.id);
       message.success("知识库删除成功");
-      fetchData();
+      await refreshAll();
     } catch {
       message.error("知识库删除失败");
     }
@@ -140,7 +197,7 @@ export default function KnowledgeBasePage() {
             isEdit={isEdit}
             data={currentKB}
             onUpdate={() => {
-              fetchData();
+              refreshAll();
             }}
             onClose={() => {
               setIsEdit(false);
@@ -150,6 +207,20 @@ export default function KnowledgeBasePage() {
         </div>
       </div>
 
+      <div className="grid grid-cols-1 gap-4">
+        <Card>
+          <div className="grid grid-cols-3">
+            {statisticsData.map((item) => (
+              <Statistic
+                title={item.title}
+                key={item.title}
+                value={`${item.value}`}
+              />
+            ))}
+          </div>
+        </Card>
+      </div>
+
       <SearchControls
         searchTerm={searchParams.keyword}
         onSearchChange={handleKeywordChange}
@@ -160,7 +231,7 @@ export default function KnowledgeBasePage() {
         viewMode={viewMode}
         onViewModeChange={setViewMode}
         showViewToggle
-        onReload={fetchData}
+        onReload={refreshAll}
       />
       {viewMode === "card" ? (
         <CardView

frontend/src/pages/KnowledgeBase/knowledge-base.api.ts

@@ -38,6 +38,11 @@ export function queryKnowledgeBaseFilesSearchUsingGet(params: RequestParams) {
   return get("/api/knowledge-base/files/search", params);
 }
 
+// 获取知识库统计
+export function getKnowledgeBaseStatisticsUsingGet() {
+  return get("/api/knowledge-base/statistics");
+}
+
 // 添加文件到知识库
 export function addKnowledgeBaseFilesUsingPost(baseId: string, data: RequestPayload) {
   return post(`/api/knowledge-base/${baseId}/files`, data);

frontend/src/pages/KnowledgeBase/knowledge-base.model.ts

@@ -25,6 +25,12 @@ export interface KnowledgeBaseItem {
   chat: never;
 }
 
+export interface KnowledgeBaseStatistics {
+  totalKnowledgeBases: number;
+  totalFiles: number;
+  totalSize: number;
+}
+
 export interface KBFile {
   id: string;
   fileName: string;