Fileupload

From Documentation

Fileupload

Employment/Purpose

There are two ways to use Fileupload: uses Fileupload as a component to upload files, or invoke Fileupload.get() to open a dialog to upload files.

Use as a Component

Fileupload itself is a component. You can use it directly as follows.

<fileupload label="Upload">
   <attribute name="onUpload">
   org.zkoss.util.media.Media media = event.getMedia();
   //then, you can process media here
   </attribute>
</fileupload>

Fileupload is actually a button with upload=true. In other words, the above is equivalent to

<button label="Upload" upload="true">
...

Please refer to Button: The Upload Property for details.

Invoke the Static Method: get

Fileupload provides a set of static methods to simplify the file uploading, such as Fileupload.get(), Fileupload.get(String, String), and so on.

The behavior is a little bit different depending on if the event thread is enabled (default: it is disabled[1]).


  1. Prior to 5.0, it is default to enabled. Refer to ZK Configuration Reference: disable-event-thread.

Event Thread Disabled

When the event thread is disabled (default), the execution won't be suspended when Fileupload.get() is called. In other words, the returned value is always null. To retrieve the uploaded files, the developer has to listen the onUpload event, which is sent when the uploading is completed.

By default, the onUpload event is sent to all root components. For example, Div will, in the following example, receive the onUpload event since it is the root component:

<div onUpload="processMedia(event.getMedias());">
    <zscript deferred="true"><![CDATA[
    import org.zkoss.util.media.Media;
 
    public void processMedia(Media[] media) {
        if (media != null) {
            for (int i = 0; i < media.length; i++) {
                if (media[i] instanceof org.zkoss.image.Image) {
                    image.setContent(media[i]);
                } else {
                    Messagebox.show("Not an image: " + media[i], "Error",
                            Messagebox.OK, Messagebox.ERROR);
                    break; //not to show too many errors
                }
            }
        }
    }
]]></zscript>
    <vbox>
        <button label="Upload" onClick="Fileupload.get(-1);" />
        <image id="image" />
    </vbox>
</div>

Specify the Target Component

[Since 5.0.2]

If you prefer the event being sent to a particular component, specify the component in the desktop's attribute called org.zkoss.zul.Fileupload.target.

For example,

desktop.setAttribute("org.zkoss.zul.Fileupload.target", mainWindow);
Fileupload.get(); //then mainWindow will receive the onUpload event

Event Thread Enabled

If the event thread is disabled, it is convenient to use Fileupload.get() and other static methods.

<zk>
	<button label="Upload">
	<attribute name="onClick">{
		org.zkoss.util.media.Media[] media = Fileupload.get(-1);
		if (media != null) {
			for (int i = 0; i &lt; media.length; i++) {
				if (media[i] instanceof org.zkoss.image.Image) {
					org.zkoss.zul.Image image = new org.zkoss.zul.Image();
					image.setContent(media[i]);
					image.setParent(pics);
				} else {
					Messagebox.show("Not an image: "+media[i], "Error", Messagebox.OK, Messagebox.ERROR);
					break; //not to show too many errors
				}
			}
		}
	}</attribute>
	</button>
	<vbox id="pics" />
</zk>

As shown, Fileupload.get(int) won't return until the end user uploads the files (and/or closes the dialog).

Example

Here is an example that uses Fileupload as a component:

<image id="img" />
Upload your hot shot:
<fileupload label="Upload" onUpload="img.setContent(event.media)" />

Supported Events

Name
Event Type
None None

Supported Children

*NONE

Use Cases

Version Description Example Location
     

Version History

Last Update : 2011/01/17


Version Date Content
5.0.2 May 2010 Able to specify a target for the onUpload event sent by Fileupload.get(). Used if the event thread is disabled.



Last Update : 2011/01/17

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