1.修复不支持文件类型提示时抛异常的问题

2.添加多媒体文件预览支持，如mp4，mp3等文件

jodconverter-web/src/main/java/cn/keking/service/impl/MediaFilePreviewImpl.java

@@ -0,0 +1,27 @@
+package cn.keking.service.impl;
+
+import cn.keking.service.FilePreview;
+import cn.keking.utils.FileUtils;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+import org.springframework.ui.Model;
+/**
+ * @author : kl
+ * @authorboke : kailing.pub
+ * @create : 2018-03-25 上午11:58
+ * @description:
+ **/
+@Service
+public class MediaFilePreviewImpl implements FilePreview {
+
+    @Autowired
+    FileUtils fileUtils;
+
+    @Override
+    public String filePreviewHandle(String url, Model model) {
+        model.addAttribute("mediaUrl", url);
+        return "media";
+    }
+
+
+}