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The zk-spring-boot Example

The example project is located on github/zkoss-demo/zk-spring-boot. To use it all you need is a command line interface (and optional: git).

This example is based on the Spring Boot - Getting Started Guide extending it by adding the required ZK dependencies and necessary configuration in order to start a ZK project with the Spring Boot platform.

Differences to a "normal" ZK Web Application


As Spring Boot prefers Java- over XML-configuration and doesn't require a classical src/main/webapp-folder (and no WEB-INF/). Hence the ZK configuration files are moved to a different files/folders:

zk.xml and were moved to a classpath location:

src/main/webapp/WEB-INF/zk.xml -> src/main/resources/metainfo/zk/zk.xml
src/main/webapp/WEB-INF/ -> src/main/resources/metainfo/

web.xml configuration such as servlets/filters are configured the "Spring Boot Way" using java configuration

src/main/webapp/WEB-INF/web.xml -> src/main/java/zk/springboot/config/ZKCEConfig / ZKEEConfig and can be changed to fit your requirements, e.g. disable websocket filter (when used with an older ZK version < 8.5) or richlet filter if not needed.

Adding them to the Spring Boot main Application class can be done using the annotations @ZKCEApplication or

public class Application  {
	public static void main(String[] args) {, args);

Also the DHtmLayoutServlet is obsolete in a jar deployment. It tried to locate zul files from the servlet context resources, which doesn't exist when deploying packaging a spring boot application as a jar file. That's why the configuration for this Servlet is commented out in this example. (In a war file it can be used as before.)

Mappings to Zul-Files as entry points for your application can be resolved with the ViewResolver, which will forward your views to ZK's dHtmlUpdateServlet internally.


Application structure

In this example the zul files are located below the class web resource folder src/main/resources/web/zul/

You can configure any folder below src/main/resources/web in

zul files can be referenced like this:

    <include src="~./zul/mvvm-page1.zul"/>
    <apply templateURI="~./zul/mvvm-page1.zul"/>

General resource folders are:

Spring Boot resources are referenced by urls starting with '/' ZK resources (including zul files) are prefixed with '~./'


    <image src="/img/zklogo1.png"/>      <!-- src/main/resources/static/img/zklogo1.png -->
    <image src="~./img/zklogo1.png"/>    <!-- src/main/resources/web/img/zklogo3.png -->

Examples how to access resources from either resource folder ar:

Zats Testing

Since Zats is running its own embedded jetty, it can't use the same application startup mechanism as plain spring boot. In order to allow Zats tests, the Application configuration must be loaded from a separate web.xml (note it is in src/test/webapp so it doesn't affect the production deployment).

(Feedback regarding a cleaner startup of a Spring Boot project in an alternative embedded container is welcome, to avoid extending/overriding Framework classes.)

As of now you can specify your test context configuration class (e.g. zk.springboot.Application) as a context parameter inside web.xml. The customized ContextLoaderListener ( reads this parameter and initializes the application context accordingly.

The PageTest case refers to this web.xml to initialize the spring boot application inside Zats' embedded Jetty.

As usual, alternative test-configuration is possible if needed.

Download/Clone the example project

With the git command line installed all you need is to clone the example repository:

   git clone

Alternatively you can download the example as a zip-package.

Once cloned/unzipped open a command line in the project folder.

In order to get started immediately the project includes the gradle-wrapper and maven-wrapper.

During the first execution gradle/maven will download itself and all the required project dependencies automatically. This will initially take quite a few minutes while showing the overall progress. Subsequent executions will be faster as gradle/maven will cache downloaded resources. For additional information on gradle/maven please refer to their official documentation.

Build / Run the Project

Please follow the instructions in the

Import the project into your IDE

The project itself designed to work from command line and independent of any IDE. Since it's both a gradle or maven project you can import it into your favorite IDE using the standard plugins provided by the IDE.

TIP: The main class zk.springboot.Application can be executed directly in your IDE for development and debugging.

Copyright © Potix Corporation. This article is licensed under GNU Free Documentation License.