使用flash/flex进行air或手机应用的开发时，有时会需要对文件和文件夹进行操作，需要综合使用File，FileStream和FileMode类。

var fileObj:File = File.documentsDirectory.resolvePath("hangge.txt");
var fs:FileStream = new FileStream();
fs.open(fileObj, FileMode.WRITE);
fs.writeUTFBytes("hangge.com");
fs.close();

2，更新文件内容
（1）下面例子在第5个字节开始覆写内容

var fileObj:File = File.documentsDirectory.resolvePath("hangge.txt");
var fs:FileStream = new FileStream();
fs.open(fileObj, FileMode.UPDATE);
fs.position = 5;
fs.writeUTFBytes(".yuhang");
fs.close();

（2）下面例子将内容添加到文件末尾

var fileObj:File = File.documentsDirectory.resolvePath("hangge.txt");
var fs:FileStream = new FileStream();
fs.open(fileObj, FileMode.APPEND);
fs.writeUTFBytes("www.hangge.com");
fs.close();

3，读取文件内容

var fileObj:File = File.documentsDirectory.resolvePath("hangge.txt");
var fs:FileStream = new FileStream();
fs.open(fileObj, FileMode.READ);
var str:String = fs.readUTFBytes(fs.bytesAvailable);
fs.close();

4，移动文件

var originalFile:File =  File.documentsDirectory.resolvePath("hangge.txt");
var newDir:File =  File.applicationStorageDirectory.resolvePath("hangge.txt");
originalFile.moveTo(newDir);

5，复制文件

var originalFile:File =  File.documentsDirectory.resolvePath("hangge.txt");
var newDir:File =  File.applicationStorageDirectory.resolvePath("hangge.txt");
originalFile.copyTo(newDir);

6，删除文件

var fileObj:File = File.documentsDirectory.resolvePath("hangge.txt");
if(fileObj.exists){
	fileObj.deleteFile();
}

7，创建文件夹

var fileDir:File = File.documentsDirectory.resolvePath("hangge");
fileDir.createDirectory();

8，移动文件夹

var originalDir:File =  File.documentsDirectory.resolvePath("hangge");
var newDir:File =  File.applicationStorageDirectory.resolvePath("hangge");
originalDir.moveTo(newDir);

9，复制文件夹

var originalDir:File =  File.documentsDirectory.resolvePath("hangge");
var newDir:File =  File.applicationStorageDirectory.resolvePath("hangge");
originalDir.copyTo(newDir);

10，删除文件夹

var fileDir:File = File.documentsDirectory.resolvePath("hangge");
if(fileDir.exists){
	fileDir.deleteDirectory();
}