There are two ways to pack the customization code: part of the Web application, or an independent JAR file. Packing as part of the Web application is straightforward. All you have to do is to specify the customization in WEB-INF/zk.xml as described in ZK Configuration Reference.

In many cases, it is better to pack the customization code as an independent JAR file, such that it can be managed separately and reused in multiple Web applications.

Where to Configure a JAR File

The configuration of a JAR file can be placed in a file called config.xml, and it must be placed under /metainfo/zk. If the JAR file also provides the component definitions, you have to prepare another file called lang-addon.xml under the same directory¹.

The content of /metainfo/zk/config.xml is similar to WEB-INF/zk.xml, except only a subset of configurations is allowed. Here is a sample (zkex.jar ‘s config.xml)²:

<config>
    <config-name>zkex</config-name><!-- used to resolve dependency -->
    <depends>zk</depends>

    <version>
        <version-class>org.zkoss.zkex.Version</version-class>
        <version-uid>5.0.6</version-uid>
        <zk-version>5.0.0</zk-version><!-- or later -->
    </version>

    <listener>
        <listener-class>org.zkoss.zkex.init.WebAppInit</listener-class>
    </listener>

    <library-property>
        <name>org.zkoss.zul.chart.engine.class</name>
        <value>org.zkoss.zkex.zul.impl.JFreeChartEngine</value>
    </library-property>
    <library-property>
        <name>org.zkoss.zul.captcha.engine.class</name>
        <value>org.zkoss.zkex.zul.impl.JHLabsCaptchaEngine</value>
    </library-property>
</config>

---

How to Initialize a JAR File

Sometimes you have to initialize a JAR file. It can be done by implementing

org.zkoss.zk.ui.util.WebAppInit

, and then specifying it as a listener in /metainfo/zk/config.xml. For example,

public class MyJARInit implements WebAppInit {
    public void init(WebApp wapp) throws Exception {
        //do whatever init you need
    }
}

Notice that many configurations can be done by accessing org.zkoss.zk.ui.util.Configuration directly. If you want to access it in

org.zkoss.zk.ui.util.WebAppInit

, invoke

org.zkoss.zk.ui.WebApp

as follows.

    public void init(WebApp wapp) throws Exception {
        Configuration config = wapp.getConfiguration();
...

1. For more information, please refer to ZK Client-side Reference: Language Definition. ↩

2. For more information, please refer to ZK Configuration Reference: JAR File’s config.xml. ↩