Download

Since 1.1.0

We usually implement file downloading through org.zkoss.zul.Filedownload when some events are triggered (For more details, please refer to ZK_Component_Reference/Essential_Components/Filedownload). Following is a simple implementation of downloading a file:

download.zul

<zk>
    <div apply="DownloadComposer">
        <button id="btn" label="download" />
    </div>
</zk>

DownloadComposer.java

public class DownloadComposer extends GenericForwardComposer {
    @Listen("onClick=#btn")
    public void download() throws IOException {
        Filedownload.save("/hello.txt", "application/octet-stream");
    }
}

The download mechanism is a process involving two steps. When you invoke save(), the Filedownload simply notifies ZK client engine of the download URL. Then, ZK client engine downloads such file according to the referred URL.

Download Files in a Test Case

In order to simulate the behavior of the ZK client engine, ZATS Mimic introduces the Resource interface which represents a downloadable resource file saved on the server. General steps for testing a download function are as follows:

1. perform some operations to trigger the download function, e.g. click a button
2. check the presence of a downloadable resource through a desktop agent
3. fetch and verify the information or content of the resource

@Test
public void test() throws Exception {
    DesktopAgent desktop = Zats.newClient().connect("/essentials/download.zul");
    Assert. assertNull (desktop. getDownloadable ());
    desktop.query("#btn").click();
    Resource resource = desktop.getDownloadable();
    Assert.assertNotNull(resource);
    Assert.assertEquals("hello..txt", resource.getName());
    String content = fetchContent(resource.getInputStream());
    Assert.assertEquals("Hello world!", content);
}

• Line 14: Click the button to trigger downloading.
• Line 15-16: Since ZATS Mimic handles the response from ZK application automatically, we can retrieve current downloadable resource files from DesktopAgent.getDownloadable(). If the method returns a null when attempting to retrieve downloadable resources, it indicates that there are no downloadable resources after the previous operation.
• Line 17-19: We can get more information from Resource, or fetch the content of resource files in binary through the input stream to verify the result.