/// <summary>通过首字节和扩展头的Length判断数据流是否消息。</summary>
/// <remarks>
/// 首字节作为Kind，然后查找是否有消息注册该Kind。
/// 对于大小写，一般要求使用扩展头的Length。
/// </remarks>
/// <param name="stream"></param>
/// <returns></returns>
public static Boolean IsMessage(Stream stream)
{
//return PeekType(stream) != null;
var p = stream.Position;
try
{
// 第一个字节很重要
var n = stream.ReadByte();
if (n < 0)
{
return(false);
}
var first = (Byte)n;
// 如果没用消息头
if (!MessageHeader.IsValid(first))
{
// 查一下该消息类型是否以注册，如果未注册，直接返回false
var type = ObjectContainer.Current.ResolveType <Message>((MessageKind)(first & 0x7F));
if (type == null)
{
return(false);
}
}
try
{
stream.Position = p;
var header = new MessageHeader();
header.Read(stream);
// 如果使用了消息头，判断一下数据流长度是否满足
if (header.HasFlag(MessageHeader.Flags.Length) && header.Length > stream.Length - stream.Position)
{
return(false);
}
}
catch
{
// 如果连消息头都读取不了，显然不对
return(false);
}
// 重新判断一下至粗恶类型
{
n = stream.ReadByte();
if (n < 0)
{
return(false);
}
first = (Byte)n;
// 查一下该消息类型是否以注册，如果未注册，直接返回false
var type = ObjectContainer.Current.ResolveType <Message>((MessageKind)(first & 0x7F));
if (type == null)
{
return(false);
}
}
return(true);
}
finally
{
stream.Position = p;
}
}
///// <summary>从流中读取消息</summary>
///// <param name="stream">数据流</param>
///// <returns></returns>
//public static Message Read(Stream stream) { return Read(stream, false); }
/// <summary>从流中读取消息</summary>
/// <param name="stream">数据流</param>
/// <param name="rwkind"></param>
/// <param name="ignoreException">忽略异常。如果忽略异常，读取失败时将返回空，并还原数据流位置</param>
/// <returns></returns>
public static Message Read(Stream stream, RWKinds rwkind = RWKinds.Binary, Boolean ignoreException = false)
{
if (stream == null || stream.Length - stream.Position < 1)
{
return(null);
}
//var reader = new BinaryReaderX(stream);
var reader = RWService.CreateReader(rwkind);
reader.Stream = stream;
Set(reader.Settings);
if (Debug)
{
reader.Debug = true;
reader.EnableTraceStream();
}
var start = stream.Position;
// 消息类型，不同序列化方法的识别方式不同
MessageKind kind = (MessageKind)0;
Type type = null;
MessageHeader header = null;
if (rwkind == RWKinds.Binary)
{
// 检查第一个字节
//var ch = reader.Reader.PeekChar();
var ch = stream.ReadByte();
if (ch < 0)
{
return(null);
}
stream.Seek(-1, SeekOrigin.Current);
var first = (Byte)ch;
#region 消息头部扩展
// 第一个字节的最高位决定是否扩展
if (MessageHeader.IsValid(first))
{
try
{
header = new MessageHeader();
header.Read(reader.Stream);
}
catch
{
stream.Position = start;
return(null);
}
// 如果使用了消息头，判断一下数据流长度是否满足
if (header.HasFlag(MessageHeader.Flags.Length) && header.Length > stream.Length - stream.Position)
{
stream.Position = start;
return(null);
}
}
#endregion
// 读取了响应类型和消息类型后，动态创建消息对象
kind = (MessageKind)(reader.ReadByte() & 0x7F);
}
else
{
// 前面的数字表示消息种类
var sb = new StringBuilder();
Char c;
while (true)
{
c = (Char)stream.ReadByte();
if (c < '0' || c > '9')
{
break;
}
sb.Append(c);
}
// 多读了一个，退回去
stream.Seek(-1, SeekOrigin.Current);
kind = (MessageKind)Convert.ToByte(sb.ToString());
//var s = stream.IndexOf(new Byte[] { (Byte)'<' });
//if (s >= 0)
//{
// var e = stream.IndexOf(new Byte[] { (Byte)'>' }, s + 1);
// if (e >= 0)
// {
// stream.Position = s;
// var msgName = Encoding.UTF8.GetString(stream.ReadBytes(e - s - 1));
// if (!String.IsNullOrEmpty(msgName) && !msgName.Contains(" ")) type = TypeX.GetType(msgName);
// }
//}
//var settings = new XmlReaderSettings();
//settings.IgnoreWhitespace = true;
//settings.IgnoreComments = true;
//var xr = XmlReader.Create(stream, settings);
//while (xr.NodeType != XmlNodeType.Element) { if (!xr.Read())break; }
//stream.Position = start;
}
#region 识别消息类型
if (type == null)
{
type = ObjectContainer.Current.ResolveType <Message>(kind);
}
if (type == null)
{
if (ignoreException)
{
stream.Position = start;
return(null);
}
else
{
throw new XException("无法识别的消息类型（Kind={0}）！", kind);
}
}
#endregion
#region 读取消息
Message msg;
if (stream.Position == stream.Length)
{
msg = TypeX.CreateInstance(type, null) as Message;
}
else
{
try
{
msg = reader.ReadObject(type) as Message;
if (msg == null)
{
throw new XException("数据格式不正确！");
}
}
catch (Exception ex)
{
if (ignoreException)
{
stream.Position = start;
return(null);
}
var em = ex.Message;
if (DumpStreamWhenError)
{
stream.Position = start;
var bin = String.Format("{0:yyyy_MM_dd_HHmmss_fff}.msg", DateTime.Now);
bin = Path.Combine(XTrace.LogPath, bin);
if (!Path.IsPathRooted(bin))
{
bin = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, bin);
}
bin = Path.GetFullPath(bin);
var dir = Path.GetDirectoryName(bin);
if (!Directory.Exists(dir))
{
Directory.CreateDirectory(dir);
}
File.WriteAllBytes(bin, stream.ReadBytes());
em = String.Format("已Dump数据流到{0}。{1}", bin, em);
}
var ex2 = new XException("无法从数据流中读取{0}（Kind={1}）消息！{2}", type.Name, kind, em);
throw ex2;
}
}
msg.Header = header;
return(msg);
#endregion
}