Add workflow bpmn file preview support (#441)

server/src/main/java/cn/keking/service/impl/BpmnFilePreviewImpl.java

@@ -0,0 +1,27 @@
+package cn.keking.service.impl;
+
+import cn.keking.model.FileAttribute;
+import cn.keking.service.FilePreview;
+import org.springframework.stereotype.Component;
+import org.springframework.ui.Model;
+
+/**
+ * @author kl (http://kailing.pub)
+ * @since 2023/3/9
+ */
+@Component
+public class BpmnFilePreviewImpl implements FilePreview {
+
+    private final CommonPreviewImpl commonPreview;
+
+    public BpmnFilePreviewImpl(CommonPreviewImpl commonPreview) {
+        this.commonPreview = commonPreview;
+    }
+
+    @Override
+    public String filePreviewHandle(String url, Model model, FileAttribute fileAttribute) {
+        commonPreview.filePreviewHandle(url,model,fileAttribute);
+        model.addAttribute("fileName", fileAttribute.getName());
+        return FilePreview.BPMN_FILE_PREVIEW_PAGE;
+    }
+}