关于Log等级，有5种，他们之间的关系可以理解为：
        调试(DEBUG)：包含调试(DEBUG)、信息(INFO)、警告(WARN)、错误(ERROR)、致命错误(FATAL)

信息(INFO)：包含信息(INFO)、警告(WARN)、错误(ERROR)、致命错误(FATAL)

警告(WARN)：包含警告(WARN)、错误(ERROR)、致命错误(FATAL)

错误(ERROR)：包含错误(ERROR)、致命错误(FATAL)

致命错误(FATAL)：只有他自己

这样，如果log4j.rootLogger = INFO，那么 INFO，WARN，ERROR，FATAL就全部会被输出
如果log4j.rootLogger = ERROR，那么ERROR，FATAL就全部会被输出

 

 

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
initialize="initializeHandler( )">
<mx:Script>
<![CDATA[
	import mx.logging.Log;
	import mx.logging.targets.TraceTarget;
	import mx.logging.LogEventLevel

	// private var _target:TraceTarget;
	private var _target:LogTarget;

	private function initializeHandler( ):void
	{
		// _target = new TraceTarget(t1); 
		_target = new LogTarget(t1); 
		_target.includeDate = true; 
		_target.includeTime = true; 
		_target.includeLevel = true; 
		_target.includeCategory = true; 
		//Only shows message in this package.
		_target.filters = ["net.nshen.logging.*" ]; 

		_target.level = LogEventLevel.INFO; 

		Log.addTarget(_target);
	}

	private function sendToLog( ):void
	{
		Log.getLogger("net.nshen.logging.MainClass").
			info("This info will be shown.");
		Log.getLogger("com.adobe.MainClass").
			info("This will not be shown due to the unmatched package.");
		Log.getLogger("net.nshen.logging.MainClass").
			debug("This is not an info, so it will not be shown.");
	}
]]>
</mx:Script>
<mx:Button click="sendToLog( )" label="Log Message"/>
	<mx:TextArea id="t1" width="306" height="154"/>
</mx:Application>

 

 

package
{
	import mx.controls.TextArea;
	import mx.core.mx_internal;
	import mx.logging.targets.LineFormattedTarget;
	import mx.logging.LogEventLevel;
 
	use namespace mx_internal;
 
	public class LogTarget extends LineFormattedTarget
	{
		public function LogTarget(tarea:TextArea)
		{
			//TODO: implement function
			super();
			this.level = LogEventLevel.INFO;
			this.includeDate = true;
			this.includeLevel = true;
			this.includeTime = true;
 
			_textArea = tarea;
		} 
 
		private var _textArea:TextArea;
 		
 		/* 		 		
     			  Descendants of this class should override this method to direct the 
     			  specified message to the desired output.
     			
     			  @param  message String containing preprocessed log message which may
     			              include time, date, category, etc. based on property settings,
     			              such as <code>includeDate</code>, <code>includeCategory</code>,
     			          etc.
     			
    			mx_internal function internalLog(message:String):void
    			{
        			// override this method to perform the redirection to the desired output
    			} 
 		 */
 		
		mx_internal override function internalLog(message:String):void
		{
			_textArea.text += message + "\n";
		} 
	}
}