File Upload and Download

From Documentation
Revision as of 14:15, 12 January 2022 by Hawk (talk | contribs) (replace tt with code (via JWB))


File Upload and Download


File Upload

Button, Toolbarbutton and Menuitem support file upload out-of-box. In other words, you just need to enable it with the steps below:

  1. Specify upload attribute with true to enable file upload
  2. Assign an onUpload event listener to the component [1]

For example:

<zk>
	<zscript>
	void upload(UploadEvent event) {
		org.zkoss.util.media.Media media = event.getMedia();
		if (media instanceof org.zkoss.image.Image) {
			org.zkoss.zul.Image image = new org.zkoss.zul.Image();
			image.setContent( (org.zkoss.image.Image) media);
			image.setParent(pics);
		} else {
			Messagebox.show("Not an image: "+media, "Error", Messagebox.OK, Messagebox.ERROR);
		}
	}
	</zscript>
	<button label="Upload" upload="true" onUpload="upload(event)"/>
	<vlayout id="pics" />
</zk>

You can control the maximal allowed number of files, the maximal allowed size, and other options. Please refer to org.zkoss.zul.Button.setUpload().

<menupopup>
    <menuitem label="Upload" upload="true,maxsize=-1,native"/>
</menupopup>



  1. If you enabled the use of event threads, you could use Fileupload.get() and related. For more information, please refer to the Event Thread section.


Open File Upload Dialog

If you want the file upload on another component rather than those components above (Button, Toolbarbutton, Menu), you can call FileUpload.get() in an event listener.


Here is an example:

    <a iconSclass="z-icon-upload" ...
       apply="org.zkoss.reference.developer.uipattern.UploadComposer"/>


public class UploadComposer extends SelectorComposer {

    @Listen(Events.ON_CLICK + "= a")
    public void handleUpload(MouseEvent e) {
        Fileupload.get(1, new EventListener<UploadEvent>() {
            public void onEvent(UploadEvent event) throws Exception {
                Media[] medias = event.getMedias();
                System.out.println("upload " +  medias[0].getName());
            }
        });
    }
}

File Download

Filedownload provides a set of utilities to prompt a user for downloading a file from the server to a local folder. For example,

<button label="Download a file" onClick='Filedownload.save("~./zklogo.png", null);'/>

10000000000002AF000001BB582C2DD7.png

The file could be a static resource, an input stream, a file, a URL and others. Please refer to ZK Component Reference and Filedownload for more information.

Version History

Last Update : 2022/01/12


Version Date Content
     


Last Update : 2022/01/12


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