Tutorial Objective

Our target application is a simple car catalog application. This application has two functions:

Search cars.
Enter a keyword in the input field, click Search and search results will be displayed in the car list below.
View details.
Click an item from the car list, the area below the car list will show the selected car's details including name, price, description, and preview.

Warm Up

This chapter guides you how to setup a project and use ZK in Eclipse. If you want to know how to build the application with ZK first, please skip it and start from Declaring Domain Class. To begin, we will start with how to prepare an environment to build a ZK web application in including setting the IDE, installing ZK, and running an application in a server.

Setup Eclipse

In this tutorial, Eclipse IDE 3.7 (indigo) for Java EE developer is used to demonstrate the building of the car catalog application. (Download Eclipse here, extract the downloaded zip file to a folder and execute eclipse.exe to run Eclipse.)

In order to edit ZK UI pages in Eclipse, add "zul" (ZK UI page's file extension name) as a content type of XML format following these steps below:

Select Window \ Preferences to open Preferences window
On the left, select General --> Content Types. On right, expand Text node in "Content types" box and select XML
Click Add and type in the content type you wish to add which is *.zul in this case, then click OK

After this has been done, Eclipse will use XML editor to open your zul file.

Install ZK in a Web Project

Download ZK

Download the ZK CE first (file name would look like zk-bin-[version].zip) and extract it to a folder.

Create a Project

To build a web application, first, create a "Dynamic Web Project" in Eclipse:

Select File \ New \ Dynamic Web Project
Enter warmup in Project name and keep every thing else default.

You can leave "Target runtime" as "none".
Notice that we set Dynamic web module version to 3.0 because we want to use Servlet 3.0 to eliminate application configuration.

Install ZK JAR

To use ZK in your project, you have to copy ZK JAR files into your project's library folder.

Copy the JAR files from the following directory to WebContent\WEB-INF\lib:

{YOUR_ZK_UNZIP_FOLDER}\dist\lib
{YOUR_ZK_UNZIP_FOLDER}\dist\lib\ext

If you prefer to use an application server that supports older (< 3.0) Servlet specification or JDK 1.5, you need to add more configuration on web.xml. Please refer to ZK Installation Guide. ^[1]

Create a Simple Page

After installation, you can create a simple zul to verify if the installation has been successful or not.

In Eclipse,

Select File \ New \ File (or File \ New \ Other \ File ) to add a new file, hello.zul, under WebContent.
Click Source tab to modify source.
Copy and paste the following sample code into hello.zul and save.

hello.zul

 <window title="My First ZK Application" border="normal">
 	Hello World!
 </window>

Now, in Project Explorer view your project would look something like:

If you cannot find Project Explorer view, select menu Window \ Show View \ Project Explorer to open it.

Run an Application

Before running a web application, we must create a server in Eclipse. Select Window \ Preferences to open Preferences window and select Server \ Runtime Environments from the left. Click Add to add a server runtime environment.

Select Apache \ Tomcat v7.0 Server as it supports Servlet 3.0 and tick Create a new local server, then click Next.

If you use JDK 1.5, you could choose Tomcat v6.0 but you will need more configuration on web.xml. Please refer to ZK Installation Guide in References .

If you have installed Tomcat 7 previously, simply provide the directory path. If you haven't, proceed with the following steps:

Click Download and Install and choose a folder.
Notice that the installation path must not contain non-ASCII characters.
Accept the license agreement and wait.
Eclipse will show an error message before installation completes, please ignore this message.

Please wait and do not interrupt the installation before it completes to ensure that the installation has been done properly.

Eclipse will download and install Tomcat into the folder you have specified.
After the installation has been completed, click Finish

Now you should be able to see a new entry in Server rumtime environments.

Right click on hello.zul and select Run As \ Run on Server to run this zul on an application server.

Choose an existing Tomcat 7. Yon can also tick Always use this server when running this project option to avoid choosing a server each time you run the application in the future. Click Finish and wait for the server to start running.

After the server starts running, Eclipse will open a browser and connect to http://localhost:8080/hello.zul automatically . If you can see the following image, then your project is ready to use ZK.

You can come back and follow these steps to run your application during this tutorial

Import and Run Example Application

We have prepared an Eclipse project zip file that contains the complete source code, you can download and import it to your Eclipse without having to start from scratch.

To use example application, follow the steps below:

Download example application project zip file.
In Eclipse, select File \ Import \ General \ Existing Projects into Workspace, choose Select archive file to import example application zip file as a project into your Eclipse.
Then follow the instructions from Run an Application to run it.

Declaring Domain Class

The following is the domain object that represents a car.

public class Car {
	private Integer id;
	private String name;
	private String company;
	private String preview;
	private String description;
	private Integer price;
	//omit getter and setter for brevity
}

Please refer to References section to see the complete code. ^[2]

We then define a service class to perform the business logic (search cars) shown below:

public interface CarService {

	/**
	 * Retrieve all cars in the catalog.
	 * @return all cars
	 */
	public List<Car> findAll();
	
	/**
	 * search cars according to keyword in name and company.
	 * @param keyword for search
	 * @return list of car that match the keyword
	 */
	public List<Car> search(String keyword);
}

In this example, we have defined a class - CarServeImpl that implements the above user interface. For simplicity, it uses a static list object as the data model. You can rewrite it so that it connects to a database in a real application. Implementation details are not in the scope of this article, please refer to References section.^[3]

Building the User Interface

UI Design is a good start to building an application as it helps you define the scope of your application. ZK provides hundreds of readily-made UI components so developers can rapidly build their desired user interface by combining and mix matching these components without having to create them from scratch.

In ZK, you can use ZK User Interface Markup Language (ZUML) ^[4], an XML-formatted language, to describe UI. By ZK's convention, the files to describe user interface with ZUML uses .zul as the name suffix. In zul files, one component can be represented as an XML element (tag) and you can configure each component's style, behavior, and function by setting XML element's attributes.^[5]

In the case of this example application, first of all, we want to design a window with specified title and normal border as our application's frame.

Extracted from search.zul

	<window title="Search" width="600px" border="normal">
		<!-- put child components inside a tag's body -->
	</window>

As window is the outermost component, it is called the root component. Window is a commonly used container because it is a basic display element of a desktop-like application while it can also enclose other components. All other components inside window are called child components and should be put in window tag's body. We set window's title bar text with "title" attribute and make window display a normal border with "border" attribute. For "width" attribute, use CSS like syntax such as "800px" or "60%".

Basically, our example application's user interface is divided into 3 areas within the window, they are (from top to bottom) search function, car list, and car details.

Search Area: ZK components are like building blocks, you can combine and mix match existing components to construct your desired UI. To allow users to search, we need a text to prompt users for input, a place to enter keywords, and a button for triggering the search. We can use the following ZK components to fulfill this requirement:

Extracted from search.zul

	 	<hbox align="center">
	 		Keyword:
	 		<textbox id="keywordBox" />
	 		<button id="searchButton" label="Search" image="/img/search.png" />
	 	</hbox>

hbox () is a layout component that arranges its child components horizontally and you can probably guess by now that the h represents horizontal. As these child components have different heights, we set the "align" attribute to "center" so they are aligned neatly along their center line. Here we also specify an "id" attribute for some components which allows you to control them by referencing their id. You can also easily create an image button by specifying the path at "image" attribute.

Car List Area. ZK provides several components to display a collection of data such as listbox, grid, and tree. In this example, we have chosen to use a listbox to display a list of cars with 3 columns: Name, Company and Price. We set the "height" attribute so the number of rows visible is limited with respect to the height specified; you can drag scroll-bar to see the rest of rows. The "emptyMessage" attribute is used to show a message when listbox contains no items. The listbox is a container component, and you can add listhead to define a column. The listitem is used to display data, and the number of listcell in one listitem should equal to the number of listheader. Here we use listcell with static value to demonstrate structure of a listitem, and we'll talk about how to create listitem upon dynamic data in next chapter.

Extracted from search.zul

	 	<listbox id="carListbox" height="160px" emptyMessage="No car found in the result">
			<listhead>
				<listheader label="Name" />
				<listheader label="Company" />
				<listheader label="Price" width="20%"/>
			</listhead>
			<listitem>
				<listcell value="product name"></listcell>
				<listcell value="company"></listcell>
				<listcell>$<label value="price" /></listcell>
			</listitem>
		</listbox>

Car Details Area. Like the hbox, vbox is also a layout component which arranges its child component in vertical order. By combing these 2 layout components, we can present more information on a screen. The "style" attribute allows you to customize component's style with CSS syntax.

Extracted from search.zul

		<hbox style="margin-top:20px">
			<image id="previewImage" width="250px" />
			<vbox>
				<label id="nameLabel" />
				<label id="companyLabel" />
				<label id="priceLabel" />
				<label id="descriptionLabel"/>
			</vbox>
		</hbox>

You can see complete zul through the link in References section. ^[6]

[1] ZK Installation Guide \ Create and Run Your First ZK Application Manually

[2] Car.java

[3] CarService.java CarServiceImpl.java

[4] ZUML Reference

[5] ZK Component Reference

[6] search.zul

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Contents

Tutorial Objective

Warm Up

Setup Eclipse

Install ZK in a Web Project

Run an Application

Import and Run Example Application

Declaring Domain Class

Building the User Interface