update

jsowell-common/src/main/java/com/jsowell/common/util/ZipUtil.java

@@ -1,6 +1,7 @@
 package com.jsowell.common.util;
 
 import com.google.common.collect.Lists;
+import org.apache.commons.collections4.CollectionUtils;
 
 import java.io.File;
 import java.io.FileOutputStream;
@@ -13,6 +14,9 @@ import java.util.zip.ZipOutputStream;
 
 public class ZipUtil {
     public static File createZipFileFromImages(List<String> imageUrls) {
+        if (CollectionUtils.isEmpty(imageUrls)) {
+            return null;
+        }
         File zipFile = new File("images.zip");
         try (FileOutputStream fos = new FileOutputStream(zipFile); ZipOutputStream zos = new ZipOutputStream(fos)) {
             for (int i = 0; i < imageUrls.size(); i++) {