How to convert WWW type to FileStream?

Now I directly convert the WWW varible to byte. But it has some problem. Firstly I want to convert the WWW to FileStream and then convert to byte. How to convert WWW type to FileStream? Thank you very much.

My code below:

int i, j, n, m = 0, nFileSize;
byte abybuf = null;
char abybufChar = null;
FileStream stFile = null;
string path;

if (flagPlatform == androidPlatform)
{

            WWW www = new WWW("jar:file://" + Application.dataPath + "!/assets/help_text.dat");
            abybuf = new byte[www.bytes.Length];
            abybuf = www.bytes;

            short[] nHelpPos = { 9, 6, 9, 9, 7, 4, 7, 8,
                                6, 6, 9, 6, 7, 7, 9, 8, 8, 7,
                                4, 9, 4, 9, 9, 9, 9, 6, 7 };

            n = 0;
            for (i = 0; i < m_stHelpList.Length; i++)
            {
                m_stHelpList = new string[nHelpPos];
                for (j = 0; j < nHelpPos; j++)
                {
                    nFileSize = (abybuf[n+=1] & 0xFF);
                    m_stHelpList[j] = System.Text.Encoding.GetEncoding("utf-8").GetString(abybuf, n, nFileSize);
                    n += nFileSize;
                }
            }
    }
    else
    {

        {
            path = Application.dataPath + "/StreamingAssets/help_text.dat";
        }
        stFile = new FileStream(path, FileMode.Open, FileAccess.Read);

        abybuf = new byte[(stFile.ReadByte() & 0xFF) | ((stFile.ReadByte() & 0xFF) << 8)];
        stFile.Read(abybuf, 0, abybuf.Length);

        short[] nHelpPos = { 9, 6, 9, 9, 7, 4, 7, 8,
                                6, 6, 9, 6, 7, 7, 9, 8, 8, 7,
                                4, 9, 4, 9, 9, 9, 9, 6, 7 };

        n = 0;
        for (i = 0; i < m_stHelpList.Length; i++)
        {
            m_stHelpList = new string[nHelpPos];
            for (j = 0; j < nHelpPos; j++)
            {
                nFileSize = (abybuf[n++] & 0xFF);
                m_stHelpList[j] = System.Text.Encoding.GetEncoding("utf-8").GetString(abybuf, n, nFileSize);
                n += nFileSize;
            }
        }

    }

Then you probably need MemoryStream not a FileStream. Both MemoryStream and FileStream are derived from Stream and they have same interface. MemoryStream takes byte as a constructor argument.