在制作JSF Ajax请求时显示加载进度

使用< f:ajax>?提出请求时,如何显示一些加载消息?
如果您还没有使用第三方组件库,该库可能已经有了一个现成的组件,例如 PrimeFaces<p:ajaxStatus>,那么您可以使用JSF提供的JavaScript jsf.ajax.addOnEvent()函数(最终还有 jsf.ajax.addOnError())挂钩对ajax事件的功能.

这是一个基本的开球示例:

<script>
    jsf.ajax.addOnEvent(function(data) {
        var ajaxstatus = data.status; // Can be "begin", "complete" and "success"
        var ajaxloader = document.getElementById("ajaxloader");

        switch (ajaxstatus) {
            case "begin": // This is called right before ajax request is been sent.
                ajaxloader.style.display = 'block';
                break;

            case "complete": // This is called right after ajax response is received.
                ajaxloader.style.display = 'none';
                break;

            case "success": // This is called when ajax response is successfully processed.
                // NOOP.
                break;
        }
    });
</script>

<img id="ajaxloader" src="ajaxloader.gif" style="display: none;" />

另见JSF 2.0 specification第13.3.5.2章:

13.3.5.2 Monitoring Events For All Ajax Requests

The JavaScript API provides the jsf.ajax.addOnEvent function that can be used to register a JavaScript function
that will be notified when any Ajax request/response event occurs. Refer to Section 14.4 “Registering Callback
Functions” for more details. The jsf.ajax.addOnEvent function accepts a JavaScript function argument that will be
notified when events occur during any Ajax request/response event cycle. The implementation must
ensure the JavaScript function that is registered must be called in accordance with the events outlined in
Section TABLE 14-3 “Events”.

您可以从http://www.ajaxload.info免费获取一些酷的ajax loader gifs.

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