合并PDF时，获取文件空指针问题

blade-service/blade-archive/src/main/java/org/springblade/archive/utils/FileUtils.java

@@ -238,13 +238,15 @@ public class FileUtils {
                     }
 
                     //获取OSS文件输入流
-                    reader = new PdfReader(CommonUtil.getOSSInputStream(urlStr));
-
-                    pageCount = reader.getNumberOfPages();
-
-                    for (int i = 0; i < pageCount; ++i) {
-                        int is = i + 1;
-                        pdfCopy.addPage(pdfCopy.getImportedPage(reader, is));
+                    InputStream inputStream = CommonUtil.getOSSInputStream(urlStr);
+                    if (inputStream != null) {
+                        reader = new PdfReader(inputStream);
+                        pageCount = reader.getNumberOfPages();
+
+                        for (int i = 0; i < pageCount; ++i) {
+                            int is = i + 1;
+                            pdfCopy.addPage(pdfCopy.getImportedPage(reader, is));
+                        }
                     }
                 } catch (Exception e) {
                     e.printStackTrace();