Java ByteArrayOutputStream.toString()方法具有什么功能呢?

ByteArrayOutputStream.toString()方法的功能:
     将ByteArrayOutputStream对象按照指定字符集转换为相应的字符串

ByteArrayOutputStream.toString()方法的语法:
     public String toString()
     public String toString(String charsetName)
     public String toString(int hibyte)
参数说明
     charsetName:指定字符集（utf-8,GB2312等）。
返回值说明
    从缓冲区内容解码的字符串

public static void main(String args[]) throws Exception
{
    InputStream in = null;
    ByteArrayOutputStream out = null;
    try
    { 
	in = new FileInputStream(new File("D:\\java265.txt"));
        out = new ByteArrayOutputStream();
        byte[] bytes = new byte[1024 * 8];
        int len = 0;
        while((len = in .read(bytes)) != -1)
        {
            out.write(bytes, 0, len);
        }
        System.out.println(out.toString("GBK"));//使用GBK编码转换成字符串
    }
    catch(FileNotFoundException e)
    {}
    finally
    {
        try
        {
            out.close(); in .close();
        }
        catch(IOException e)
        {}
    }
}