Stream/Bytes[]/Image对象相互转化

 转自：  http://www.cnblogs.com/fanyong/p/3938017.html

Stream/Bytes[]/Image对象相互转化

Stream转Byte数组、Image转Byte数组、文件转Stream等

/// <summary>
/// 将 Stream 转成 byte[]
/// </summary>
/// <param name="stream"></param>
/// <returns></returns>
public static byte[] StreamToBytes(Stream stream)
{
    byte[] bytes = new byte[stream.Length];
    stream.Read(bytes, 0, bytes.Length);
    // 设置当前流的位置为流的开始
    stream.Seek(0, SeekOrigin.Begin);
    return bytes;
}

/// <summary>
/// 将 byte[] 转成 Stream
/// </summary>
/// <param name="bytes"></param>
/// <returns></returns>
public static Stream BytesToStream(byte[] bytes)
{
    Stream stream = new MemoryStream(bytes);
    return stream;
}

/// <summary> 
/// 字节流转换成图片 
/// </summary> 
/// <param name="byt">要转换的字节流</param> 
/// <returns>转换得到的Image对象</returns> 
public static Image BytToImg(byte[] byt)
{
    try
    {
        MemoryStream ms = new MemoryStream(byt);
        Image img = Image.FromStream(ms);
        return img;
    }
    catch (Exception ex)
    {
        LogHelper.WriteError("StreamHelper.BytToImg 异常", ex);
        return null;
    }
}

/// <summary>
///  图片转换成字节流 
/// </summary>
/// <param name="img"></param>
/// <returns></returns>
public static byte[] ImageToByteArray(Image img)
{
    ImageConverter imgconv = new ImageConverter();
    byte[] b = (byte[])imgconv.ConvertTo(img, typeof(byte[]));
    return b;
}

/// <summary>
/// 把图片Url转化成Image对象
/// </summary>
/// <param name="imageUrl"></param>
/// <returns></returns>
public static Image Url2Img(string imageUrl)
{
    try
    {
        if (string.IsNullOrEmpty(imageUrl))
        {
            return null;
        }

        WebRequest webreq = WebRequest.Create(imageUrl);
        WebResponse webres = webreq.GetResponse();
        Stream stream = webres.GetResponseStream();
        Image image;
        image = Image.FromStream(stream);
        stream.Close();

        return image;
    }
    catch (Exception ex)
    {
        LogHelper.WriteError("StreamHelper.Url2Img 异常", ex);
    }

    return null;
}

/// <summary>
/// 把本地图片路径转成Image对象
/// </summary>
/// <param name="imagePath"></param>
/// <returns></returns>
public static Image ImagePath2Img(string imagePath)
{
    try
    {
        if (string.IsNullOrEmpty(imagePath))
        {
            return null;
        }

        byte[] bytes = Image2ByteWithPath(imagePath);
        Image image = BytToImg(bytes);
        return image;
    }
    catch (Exception ex)
    {
        LogHelper.WriteError("StreamHelper.ImagePath2Img 异常", ex);
        return null;
    }
}