feat(image): 优化图片上传和预览功能

- 修改图片上传接口，支持用户 ID 和 Markdown ID 参数
- 实现在线预览功能，支持多种文件类型
- 优化图片插入到 Markdown 编辑器的逻辑
- 更新数据库配置和连接字符串

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

@@ -8,10 +8,15 @@ import io.swagger.v3.oas.annotations.Operation;
 import io.swagger.v3.oas.annotations.Parameter;
 import io.swagger.v3.oas.annotations.Parameters;
 import io.swagger.v3.oas.annotations.tags.Tag;
+import jakarta.servlet.http.HttpServletResponse;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.util.StreamUtils;
 import org.springframework.web.bind.annotation.*;
 import org.springframework.web.multipart.MultipartFile;
 
+import java.io.File;
+import java.io.FileInputStream;
 import java.io.IOException;
 import java.util.List;
 
@@ -20,19 +25,21 @@ import java.util.List;
 @RequestMapping("/api/images")
 public class ImageController {
 
+    @Value("${file.upload-dir}")
+    private String rootPath;
+
     @Autowired
     private ImageService imageService;
 
     @Operation(summary = "上传图片")
-    @Parameters({
-            @Parameter(name = "file", description = "图片文件", required = true)
-    })
     @PostMapping
     public R<Image> uploadImage(
-            @RequestParam("file") MultipartFile file) {
+            @RequestParam("file") MultipartFile file,
+            @RequestParam(value = "userId", required = false) Long userId,
+            @RequestParam(value = "markdownId", required = false) Long markdownId) {
 
         try {
-            Image image = imageService.uploadImage(file);
+            Image image = imageService.uploadImage(file, userId, markdownId);
             return R.success(image);
         } catch (IOException e) {
             return R.fail();
@@ -50,6 +57,33 @@ public class ImageController {
         }
     }
 
+    /**
+     * 在线预览（图片、视频、音频、pdf 等浏览器可直接识别的类型）
+     */
+    @GetMapping("/preview/{url}")
+    @Operation(summary = "在线预览", description = "浏览器直接打开文件流")
+    public void preview(@PathVariable String url, HttpServletResponse resp) throws IOException {
+        if (url == null) {
+            resp.setStatus(404);
+            R.fail("文件不存在");
+        }
+        File file = new File(rootPath + File.separator + url);
+        if (!file.exists()) {
+            resp.setStatus(404);
+            R.fail("文件不存在");
+        }
+        String contentTypeFromFileExtension = getContentTypeFromFileExtension(url);
+        // 设置正确的 MIME
+        resp.setContentType(contentTypeFromFileExtension);
+        // 设置文件长度，支持断点续传
+        resp.setContentLengthLong(file.length());
+        // 写出文件流
+        try (FileInputStream in = new FileInputStream(file)) {
+            StreamUtils.copy(in, resp.getOutputStream());
+        }
+    }
+
+
     @Operation(summary = "根据url删除图片")
     @PostMapping("/deleteByUrl")
     public R<Void> deleteImageByUrl(@RequestParam String url) {
@@ -73,4 +107,34 @@ public class ImageController {
     }
 
 
+    /**
+     * 根据文件扩展名获取内容类型
+     * @param fileName 文件名
+     * @return 对应的MIME类型
+     */
+    private String getContentTypeFromFileExtension(String fileName) {
+        if (fileName == null || fileName.lastIndexOf('.') == -1) {
+            return "application/octet-stream";
+        }
+
+        String extension = fileName.substring(fileName.lastIndexOf('.') + 1).toLowerCase();
+        switch (extension) {
+            case "jpg":
+            case "jpeg":
+                return "image/jpeg";
+            case "png":
+                return "image/png";
+            case "gif":
+                return "image/gif";
+            case "bmp":
+                return "image/bmp";
+            case "webp":
+                return "image/webp";
+            case "svg":
+                return "image/svg+xml";
+            default:
+                return "application/octet-stream";
+        }
+    }
+
 }