flex自定义Log的输出，重写隐藏方法

flex自带了mx.logging包，跟log4j很像。基本用法挺简单不讲了。

flex同时还实现了两种log的输出方式，在mx.logging.targets包，分别是MiniDebugTarget和TraceTarget（输出到LocalConnection和trace），可是有时候不想用这两种，比如想输出到TextArea显示。注意到这两个都是继承自LineFormattedTarget，看看这类忍不住有点激动了，因为它做了大部分的字符串格式化操作，直接拿来继承就行了。从文档上看它只有logEvent可以重写，而且又不大方便（因为LogEvent里的message不是格式化好的，要了有啥意思）。翻看源码才知道它有一个方法是mx_internal命名空间的，即隐藏的。（不过可以重写）

/**
*  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
}

重写它就显得很简单，看看TraceTarget的源码也是重写它的。下面是自定义输出类

package myvocal.log
{
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;

mx_internal override function internalLog(message:String):void
{
_textArea.text += message + "/n";
}

}
}