feat(biji-houdaun): 支持 Markdown 文件上传、预览、编辑和创建

- 新增 Markdown 文件预览功能
- 更新 Markdown 文件创建和编辑接口，使用 Long 类型的 ID
- 优化图片上传接口，支持 Long 类型的用户 ID 和 Markdown ID
- 重构 MarkdownFileService接口，增加获取 Markdown 文件的方法
- 修改 MarkdownFileServiceImpl 实现类，支持新的 Markdown 文件操作

biji-houdaun/src/main/java/com/test/bijihoudaun/controller/ImageController.java

@@ -31,8 +31,8 @@ public class ImageController {
     })
     @PostMapping
     public ResponseEntity<Image> uploadImage(
-            @RequestParam Integer userId,
-            @RequestParam(required = false) Integer markdownId,
+            @RequestParam Long userId,
+            @RequestParam(required = false) Long markdownId,
             @RequestParam("file") MultipartFile file) {
 
         try {
@@ -42,4 +42,4 @@ public class ImageController {
             return ResponseEntity.status(500).build();
         }
     }
-}
+}

biji-houdaun/src/main/java/com/test/bijihoudaun/controller/MarkdownController.java

@@ -17,6 +17,19 @@ public class MarkdownController {
     @Autowired
     private MarkdownFileService markdownFileService;
 
+    @Operation(summary = "预览markdown文件")
+    @Parameters({
+        @Parameter(name = "id", description = "文件ID", required = true)
+    })
+    @GetMapping("/{id}")
+    public ResponseEntity<String> getMarkdownContent(@PathVariable Long id) {
+        MarkdownFile file = markdownFileService.getMarkdownById(id);
+        if (file != null) {
+            return ResponseEntity.ok(file.getContent());
+        }
+        return ResponseEntity.notFound().build();
+    }
+
     @Operation(summary = "创建markdown文件")
     @Parameters({
             @Parameter(name = "userId", description = "用户id",required = true),
@@ -26,7 +39,7 @@ public class MarkdownController {
     })
     @PostMapping
     public ResponseEntity<MarkdownFile> createMarkdown(
-            @RequestParam Integer userId,
+            @RequestParam Long userId,
             @RequestParam String title,
             @RequestParam String fileName,
             @RequestBody String content) {
@@ -44,7 +57,7 @@ public class MarkdownController {
     })
     @PostMapping("/{id}")
     public ResponseEntity<MarkdownFile> updateMarkdown(
-            @PathVariable Integer id,
+            @PathVariable Long id,
             @RequestBody String content) {
 
         MarkdownFile file = markdownFileService.updateMarkdownContent(id, content);