这是我正在使用的功能，测试和工作良好。 请记住“input”不应该是空的，而应该是“input”。Position '应该在读取之前重置为'0'，否则它将打破读取循环，并且不会读取任何东西来转换为数组。

    public static byte[] StreamToByteArray(Stream input)
    {
        if (input == null)
            return null;
        byte[] buffer = new byte[16 * 1024];
        input.Position = 0;
        using (MemoryStream ms = new MemoryStream())
        {
            int read;
            while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
            {
                ms.Write(buffer, 0, read);
            }
            byte[] temp = ms.ToArray();

            return temp;
        }
    }

如果有人喜欢它，这里有一个。net 4+的解决方案，它是一个扩展方法，没有对MemoryStream进行不必要的Dispose调用。这是一个无可救药的琐碎优化，但值得注意的是，未能Dispose MemoryStream并不是真正的失败。

public static class StreamHelpers
{
    public static byte[] ReadFully(this Stream input)
    {
        var ms = new MemoryStream();
        input.CopyTo(ms);
        return ms.ToArray();
    }
}

这真的取决于你是否可以信任。对于许多流，你只是不知道会有多少数据。在这种情况下——在。net 4之前——我会使用这样的代码:

public static byte[] ReadFully(Stream input)
{
    byte[] buffer = new byte[16*1024];
    using (MemoryStream ms = new MemoryStream())
    {
        int read;
        while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
        {
            ms.Write(buffer, 0, read);
        }
        return ms.ToArray();
    }
}

对于。net 4及以上版本，我将使用Stream。CopyTo，这基本上相当于我代码中的循环-创建MemoryStream，调用stream.CopyTo(ms)，然后返回ms. toarray()。工作。

我也许应该解释一下为什么我的答案比其他人的长。流。Read不能保证它会读取所有要求的内容。例如，如果您正在从网络流中读取数据，它可能会读取一个数据包的值，然后返回，即使很快会有更多的数据。主题。Read将一直进行到流的结束或指定的大小，但您仍然必须知道开始时的大小。

The above method will keep reading (and copying into a MemoryStream) until it runs out of data. It then asks the MemoryStream to return a copy of the data in an array. If you know the size to start with - or think you know the size, without being sure - you can construct the MemoryStream to be that size to start with. Likewise you can put a check at the end, and if the length of the stream is the same size as the buffer (returned by MemoryStream.GetBuffer) then you can just return the buffer. So the above code isn't quite optimised, but will at least be correct. It doesn't assume any responsibility for closing the stream - the caller should do that.

有关更多信息(以及另一种实现)，请参阅本文。

在命名空间RestSharp中。扩展有ReadAsBytes方法。在这个方法中使用的是MemoryStream，在本页的一些例子中有相同的代码，但当你使用RestSharp时，这是最简单的方法。

using RestSharp.Extensions;
var byteArray = inputStream.ReadAsBytes();

如果流支持Length属性，则可以直接创建字节数组。其优点是MemoryStream。ToArray创建两次数组。另外，缓冲区中可能还有一些未使用的额外字节。此解决方案分配所需的精确数组。如果流不支持Length属性，它将抛出NotSupportedException异常。

同样值得注意的是，数组不能大于int.MaxValue。

public static async Task<byte[]> ToArrayAsync(this Stream stream)
{
    var array = new byte[stream.Length];
    await stream.ReadAsync(array, 0, (int)stream.Length);
    return array;
}

根据流是否支持搜索在两个版本之间切换的完整代码。它包括检查位置和不可靠的长度。这可能会略微降低速度。在我的测试中，ToArrayAsyncDirect比ToArrayAsyncGeneral快3倍。

public static class StreamExtensions
{
    public static readonly byte[] TempArray = new byte[4];

    /// <summary>
    /// Converts stream to byte array.
    /// </summary>
    /// <param name="stream">Stream</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>Stream data as array</returns>
    /// <returns>Binary data from stream in an array</returns>
    public static async Task<byte[]> ToArrayAsync(this Stream stream, CancellationToken cancellationToken)
    {
        if (!stream.CanRead)
        {
            throw new AccessViolationException("Stream cannot be read");
        }

        if (stream.CanSeek)
        {
            return await ToArrayAsyncDirect(stream, cancellationToken);
        }
        else
        {
            return await ToArrayAsyncGeneral(stream, cancellationToken);
        }
    }

    /// <summary>
    /// Converts stream to byte array through MemoryStream. This doubles allocations compared to ToArrayAsyncDirect.
    /// </summary>
    /// <param name="stream">Stream</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns></returns>
    private static async Task<byte[]> ToArrayAsyncGeneral(Stream stream, CancellationToken cancellationToken)
    {
        using MemoryStream memoryStream = new MemoryStream();
        await stream.CopyToAsync(memoryStream, cancellationToken);
        return memoryStream.ToArray();
    }

    /// <summary>
    /// Converts stream to byte array without unnecessary allocations.
    /// </summary>
    /// <param name="stream">Stream</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>Stream data as array</returns>
    /// <exception cref="ArgumentException">Thrown if stream is not providing correct Length</exception>
    private static async Task<byte[]> ToArrayAsyncDirect(Stream stream, CancellationToken cancellationToken)
    {
        if (stream.Position > 0)
        {
            throw new ArgumentException("Stream is not at the start!");
        }


        var array = new byte[stream.Length];
        int bytesRead = await stream.ReadAsync(array, 0, (int)stream.Length, cancellationToken);

        if (bytesRead != array.Length ||
            await stream.ReadAsync(TempArray, 0, TempArray.Length, cancellationToken) > 0)
        {
            throw new ArgumentException("Stream does not have reliable Length!");
        }

        return array;
    }
}

创建一个helper类，并在任何希望使用它的地方引用它。

public static class StreamHelpers
{
    public static byte[] ReadFully(this Stream input)
    {
        using (MemoryStream ms = new MemoryStream())
        {
            input.CopyTo(ms);
            return ms.ToArray();
        }
    }
}