Does Keikai support user permission control?

We provide API for you to build your owned permission control. User permission feature involves authentication and authorization which is out of Keikai function’s scope. Since Keikai cannot identify a user, it cannot assign a user with corresponding permissions. But you can easily integrate existing framework like Spring Security and implement your user permission features with Keikai. Please refer to the following sections:

  • Hide the toolbar and the context menu to prevent editing. Please refer to Control Component.
  • Disable available functions for different users. Please refer to Disable Functions.
  • Protect sheets and set available actions. Refer to io.keikai.api.Range.

You can see an example at Use_Case/User_Permission.

How do I save the content of Keikai or even save it to a database?

To save the content of Keikai, you can export it as an Excel file. It is also the way we implement the “Save” function in zssapp. After exporting, you can save the file into a BLOB type column of a database.

Alternatively you can save data to the database referencing the Tutorial.

After exporting to a PDF file, the PDF shows unexpected fonts or has missing characters

There are many reasons, but we list the most common ones:

  • You choose the wrong encoding for some characters.

  • For example, you applied “Calibri” to a Chinese character. You can resolve it by applying the correct font.
    • The computer of your PDF viewer software doesn’t install corresponding fonts. For Keikai doesn’t embed fonts into a exported PDF file, your computer should install the corresponding fonts to display the file correctly. You can test it by opening the PDF file in another computer or different OS. Please check installed fonts on your computer. Installing missing fonts can solve this problem.
  • iText bundled in Keikai will find fonts from the following paths. Please check the fonts you apply are available in these paths:

It won’t scan its subdirectories


It will scan its subdirectories


Extracted from FontFactoryImp com.lowagie.text.FontFactoryImp.

  • The corresponding font is not installed the server that exports PDF files.
    It might happen when you export a PDF on a Linux server without Microsoft fonts installed. (Unbuntu should install the package ttf-mscorefonts-installer, “installer for Microsoft TrueType core fonts”). You will find the exported PDF’s size is smaller than the one exported correctly. Install the corresponding fonts can solve this issue.

How do I know my file can be loaded correctly by Keikai?

In general, those functions we implement with the toolbar are supported. However, the best way is to download Keikai Demo App and try it yourself. It’s a ready-to-use web application based on Keikai component. You just run the war with a Java application server, then you can upload files via the menu, File / Open / Upload.

Is Keikai 100% compatible with Excel?

Keikai’s core value is to bring spreadsheets online and be able to control them fully in Java. Regarding Excel compatibility, while we support the most commonly used Excel features, that doesn’t mean all features and all Excel versions are supported. Our documentation contains a list of supported features, for example:

Please check our documentaiton for supported features, or consult with us if you have any doubts.

Does Keikai support VB macro?

No. Even MS Office 365 doesn’t support VB Macro in the Web.

If you need a similar function, you can port your macro to Java in your controller to achieve the same.

How to validate an XLSX format Excel file

Validate it with Open XML SDK 2.5 Productivity Tool for Microsoft Office.

Run out of heap when exporting / importing a large file

It is possible to encounter an error like java.lang.OutOfMemoryError: Java heap space when exporting / importing a large file, since large file consumes more memory during importing and exporting process. Please increase your JVM heap size. (You can refer to this document)

What is the maximal rows and columns Keikai supports?

  • The max column is 16384 (2^14)
  • the max row is 1048576 (2^20)

Keikai renders cells on demand instead of rendering all cells at once in a browser, but it loads a file’s whole content into the memory. So the bigger memory your server has, the more rows and columns Keikai can load.

Even if you have sufficient memory, loading time could be an issue. Because loading time grows linearly with cell number. Under our test machine, loading 1 million cells with texts takes 65 seconds, loading 2 million cells takes 139 seconds and loading 4 million cells takes 315 seconds. As the cell number grows, the time could be too long to be acceptable by users. You can measure the loading time on your machine first.

Does Keikai support Excel form controls?

No, you can’t import Excel’s form controls into Keikai. However there are ways to achieve the same goal:

Insert a checkbox or a radio symbol in cells and control it

To enable the selection of checkmarks and radios, you can implement Cell Clicking Event listener and switch the symbols and perform corresponding selection actions. Please see InvoiceBuilderController.

Use ZK Components

Keikai works well with ZK Framework and you can leverage ZK Components in Keikai easily. Please refer to the menu in Keikai Demo: Excel-like and Bringing intuitive input controls to the web spreadsheet user experience with Java

Turn a cell into a button

Apply a border and a background you can easily make a cell look like a button. Then, control the cell in Java so that it works like a button.

Check ui-controls.xlsx in the example project.

To listen to the button clicking, please see Cell Clicking Event.

Create a custom context menu

Please refer to Custom Context Menu. Then you can implement the application logic in an onCellClick event listener.

Data validation can display a dropdown list

Please refer to Data Validation.

Show an input component in a popup

Please see formControl.zul

Unable to get property ‘appendCell’ of undefined or null reference in IE

If you visit Keikai with IE11 and see such error message in developer tool’s console, it is most likely caused by using Compatibility View. Please turn it off and reload the page again since ZK/Keikai don’t support such legacy mode.

Errors When Copying Massive Cells

Request Parameter Over a Server’s Limit

You might see similar errors in your server console when copying a large amount of cells. For example, in Tomcat the error message looks like:

25-Jun-2018 12:14:26.420 INFO [http-nio-8080-exec-8] org.apache.tomcat.util.http.Parameters.processParameters More than the maximum number of request parameters (GET plus POST) for a single request ([10,000]) were detected. Any parameters beyond this limit have been ignored. To change this limit, set the maxParameterCount attribute on the Connector. Note: further occurrences of this error will be logged at DEBUG level.

You need to increase the limit of maxParameterCount of your web container. Read more.

How do I understand xlsx file format?

Please read Structure of a SpreadsheetML document. You can also download ECMA-376 Office Open XML file formats.

Get code at GitHub