/// <summary> 

/// 将 Stream 转成 byte[] 

/// </summary> 

public 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> 

public Stream BytesToStream(byte[] bytes) 

{ 

    Stream stream = new MemoryStream(bytes); 

    return stream; 

} 

/// <summary> 

/// 将 Stream 写入文件 

/// </summary> 

public void StreamToFile(Stream stream,string fileName) 

{ 

    // 把 Stream 转换成 byte[] 

    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); 

    // 把 byte[] 写入文件 

    FileStream fs = new FileStream(fileName, FileMode.Create); 

    BinaryWriter bw = new BinaryWriter(fs); 

    bw.Write(bytes); 

    bw.Close(); 

    fs.Close(); 

} 

/// <summary> 

/// 从文件读取 Stream 

/// </summary> 

public Stream FileToStream(string fileName) 

{             

    // 打开文件 

    FileStream fileStream = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.Read); 

    // 读取文件的 byte[] 

    byte[] bytes = new byte[fileStream.Length]; 

    fileStream.Read(bytes, 0, bytes.Length); 

    fileStream.Close(); 

    // 把 byte[] 转换成 Stream 

    Stream stream = new MemoryStream(bytes); 

    return stream; 

}