url - Adobe Air 如何检查 URL 是否在线\给出任何响应存在？

Question

我有一个网址，我想检查它是否有效。我想获得 bool 值。怎么做这样的事情？

Answer 1

您可以使用 URLLoader 并监听事件来检查它是否加载，如果没有加载，可能是什么问题。首先使用 AIRMonitor 来确保客户的计算机处于在线状态会很方便。

这是我开始编写的一个类来说明这个想法:

package  
{
    import flash.events.Event;
    import flash.events.EventDispatcher;
    import flash.events.HTTPStatusEvent;
    import flash.events.IEventDispatcher;
    import flash.events.IOErrorEvent;
    import flash.events.SecurityErrorEvent;
    import flash.net.URLLoader;
    import flash.net.URLRequest;

    /**
     * ...
     * @author George Profenza
     */
    public class URLChecker extends EventDispatcher
    {
        private var _url:String;
        private var _request:URLRequest;
        private var _loader:URLLoader;
        private var _isLive:Boolean;
        private var _liveStatuses:Array;
        private var _completeEvent:Event;
        private var _dispatched:Boolean;
        private var _log:String = '';

        public function URLChecker(target:IEventDispatcher = null) 
        {
            super(target);
            init();
        }

        private function init():void
        {
            _loader = new URLLoader();
            _loader.addEventListener(Event.COMPLETE, _completeHandler);
            _loader.addEventListener(HTTPStatusEvent.HTTP_STATUS, _httpStatusHandler);
            _loader.addEventListener(IOErrorEvent.IO_ERROR, _ioErrorEventHandler);
            _loader.addEventListener(SecurityErrorEvent.SECURITY_ERROR, _securityErrorHandler);

            _completeEvent = new Event(Event.COMPLETE, false, true);

            _liveStatuses = [];//add other acceptable http statuses here
        }

        public function check(url:String = 'http://stackoverflow.com'):void {
            _dispatched = false;
            _url = url;
            _request = new URLRequest(url);
            _loader.load(_request);
            _log += 'load for ' + _url + ' started : ' + new Date() + '\n';
        }

        private function _completeHandler(e:Event):void 
        {
            _log += e.toString() + ' at ' + new Date();
            _isLive = true;
            if (!_dispatched) {
                dispatchEvent(_completeEvent);
                _dispatched = true;
            }
        }

        private function _httpStatusHandler(e:HTTPStatusEvent):void 
        {
            /* comment this in when you're sure what statuses you're after
            var statusesLen:int = _liveStatuses.length;
            for (var i:int = statusesLen; i > 0; i--) {
                if (e.status == _liveStatuses[i]) {
                    _isLive = true;
                    dispatchEvent(_completeEvent);
                }
            }
            */
            //200 range
            _log += e.toString() + ' at ' + new Date();
            if (e.status >= 200 && e.status < 300) _isLive = true;
            else                                   _isLive = false;
            if (!_dispatched) {
                dispatchEvent(_completeEvent);
                _dispatched = true;
            }
        }

        private function _ioErrorEventHandler(e:IOErrorEvent):void 
        {
            _log += e.toString() + ' at ' + new Date();
            _isLive = false;
            if (!_dispatched) {
                dispatchEvent(_completeEvent);
                _dispatched = true;
            }
        }

        private function _securityErrorHandler(e:SecurityErrorEvent):void 
        {
            _log += e.toString() + ' at ' + new Date();
            _isLive = false;
            if (!_dispatched) {
                dispatchEvent(_completeEvent);
                _dispatched = true;
            }
        }

        public function get isLive():Boolean { return _isLive; }

        public function get log():String { return _log; }

    }

}

这是一个基本用法示例:

var urlChecker:URLChecker = new URLChecker();
urlChecker.addEventListener(Event.COMPLETE, urlChecked);
urlChecker.check('wrong_place.url');

function urlChecked(event:Event):void {
    trace('is Live: ' + event.target.isLive);
    trace('log: ' + event.target.log);
}

这个想法很简单: 1. 您创建一个已检查的 2.监听COMPLETE事件(有结果时触发 3. 在处理程序中检查它是否处于事件状态以及记录的内容。

在 HTTP specs , 200 区域似乎没问题，但根据您加载的内容，您可能需要 来调整类(class)。此外，您还需要更好地处理安全/跨域问题，但至少这是一个开始。

HTH