一个Stream的封装——WrapStream

写代码的时候经常遇到要将stream里面的某些函数修改一下，方便打桩或提供新功能。但由于CLR里面提供的Stream大部分都是sealed类型的。这个时候我们往往通过新建一个Stream类来封装现有stream成新stream。

    class WrapStream : Stream
    {
        Stream stream;
        public WrapStream(Stream stream)
        {
            this.stream = stream;
        }

        public override bool CanRead { get { return stream.CanRead; } }

        public override bool CanSeek { get { return stream.CanSeek; } }

        public override bool CanWrite { get { return stream.CanWrite; } }

        public override long Length { get { return stream.Length; } }

        public override long Position
        {
            get { return stream.Position; }
            set { stream.Position = value; }
        }

        public override void Flush()
        {
            stream.Flush();
        }

        public override int Read(byte[] buffer, int offset, int count)
        {
            return stream.Read(buffer, offset, count);
        }

        public override long Seek(long offset, SeekOrigin origin)
        {
            return stream.Seek(offset, origin);
        }

        public override void SetLength(long value)
        {
            stream.SetLength(value);
        }

        public override void Write(byte[] buffer, int offset, int count)
        {
            stream.Write(buffer, offset, count);
        }

        public override void Close()
        {
            stream.Close();
        }

        protected override void Dispose(bool disposing)
        {
            stream.Dispose();
        }
    }

虽然本身这个实现并不难，但由于.net并没有内置这个wrapstream，每次都要实现有点烦，这里记录一下，以后再用的时候直接继承这个WrapStream，只重写需要特化的部分即可。另外，这个WrapStream可能也不够完善，后续有更正再补充。