ue4同c#通信时的中文乱码问题

本文讨论C#同ue4进行通信，出现的中文乱码情况，其他语言类似。

本文分两种情况讨论，

1.C#向ue4发送string

在C#发送string时，要先区分发送的字符串中是否包含中文，判断方法很简单，如下：

        private bool IsPureAnsi(string str)         {             for (int i = 0; i < str.Length; ++i)             {                 if ((int)str[i] > 127)                 {                     return false;                 }             }              return true;         }

当string中不包含中文时，每个字符占1个字节，string前要先发送string的长度，占4个字节，string结束要加'\0'结尾（c传统）

当string中包含中文时，每个字节占用2个字节，格式同上（注意string长度无需*2，而且string长度要取反，string结尾需要两个字节的'\0'）

具体代码如下：

        public byte[] StringToBytes(string str)         {             Stream stream = new MemoryStream();              if (this.IsPureAnsi(str))             {                 byte[] strLenBytes = System.BitConverter.GetBytes(str.Length + 1);                 stream.Write(strLenBytes, 0, strLenBytes.Length);                  byte[] strBytes = Encoding.ASCII.GetBytes(str);                 stream.Write(strBytes, 0, strBytes.Length);                 stream.WriteByte(0);             }             else             {                 int strLen = str.Length + 1;                 byte[] strLenBytes = System.BitConverter.GetBytes(-strLen);                 stream.Write(strLenBytes, 0, strLenBytes.Length);                  byte[] strBytes = Encoding.Unicode.GetBytes(str);                 stream.Write(strBytes, 0, strBytes.Length);                 stream.WriteByte(0);                 stream.WriteByte(0);             }              return StreamToBytes(stream);         }

2.ue4向C#发送string

这种情况，ue4端照常发送，c#解析的时候需要做一定处理

c#在接收到string数据时，先取出string长度信息，如果string长度>=0,则说明c#接收到的string是ascii编码，如果小于0，说明接收到的string是unicode编码

具体代码如下

        public String GetString(byte[] data, int index, out int outIndex)         {             int strLen = System.BitConverter.ToInt32(data, index);             bool Ascii = strLen >= 0;             if (Ascii)             {                 outIndex = index + 4 + strLen;                  int begin = index + 4;                 int end = outIndex;                 byte[] byteStr = data.Skip(begin).Take(end - begin - 1).ToArray();                  string str = Encoding.Default.GetString(byteStr);                 return str;             }             else             {                 strLen = -strLen;                 outIndex = index + 4 + strLen*2;                  int begin = index + 4;                 int end = outIndex;                 byte[] byteStr = data.Skip(begin).Take(end - begin - 2).ToArray();                  string str = Encoding.Unicode.GetString(byteStr);                 return str;             }         }

以上内容主要参考的是ue4中的源码，具体源码如下：

FArchive& operator<<( FArchive& Ar, FString& A ) { 	// > 0 for ANSICHAR, < 0 for UCS2CHAR serialization  	if (Ar.IsLoading()) 	{ 		int32 SaveNum; 		Ar << SaveNum;  		bool LoadUCS2Char = SaveNum < 0; 		if (LoadUCS2Char) 		{ 			SaveNum = -SaveNum; 		}  		// If SaveNum is still less than 0, they must have passed in MIN_INT. Archive is corrupted. 		if (SaveNum < 0) 		{ 			Ar.ArIsError = 1; 			Ar.ArIsCriticalError = 1; 			UE_LOG(LogNetSerialization, Error, TEXT("Archive is corrupted")); 			return Ar; 		}  		auto MaxSerializeSize = Ar.GetMaxSerializeSize(); 		// Protect against network packets allocating too much memory 		if ((MaxSerializeSize > 0) && (SaveNum > MaxSerializeSize)) 		{ 			Ar.ArIsError         = 1; 			Ar.ArIsCriticalError = 1; 			UE_LOG( LogNetSerialization, Error, TEXT( "String is too large" ) ); 			return Ar; 		}  		// Resize the array only if it passes the above tests to prevent rogue packets from crashing 		A.Data.Empty           (SaveNum); 		A.Data.AddUninitialized(SaveNum);  		if (SaveNum) 		{ 			if (LoadUCS2Char) 			{ 				// read in the unicode string and byteswap it, etc 				auto Passthru = StringMemoryPassthru<UCS2CHAR>(A.Data.GetData(), SaveNum, SaveNum); 				Ar.Serialize(Passthru.Get(), SaveNum * sizeof(UCS2CHAR)); 				// Ensure the string has a null terminator 				Passthru.Get()[SaveNum-1] = '\0'; 				Passthru.Apply();  				INTEL_ORDER_TCHARARRAY(A.Data.GetData())  				// Since Microsoft's vsnwprintf implementation raises an invalid parameter warning 				// with a character of 0xffff, scan for it and terminate the string there. 				// 0xffff isn't an actual Unicode character anyway. 				int Index = 0; 				if(A.FindChar(0xffff, Index)) 				{ 					A[Index] = '\0'; 					A.TrimToNullTerminator();		 				} 			} 			else 			{ 				auto Passthru = StringMemoryPassthru<ANSICHAR>(A.Data.GetData(), SaveNum, SaveNum); 				Ar.Serialize(Passthru.Get(), SaveNum * sizeof(ANSICHAR)); 				// Ensure the string has a null terminator 				Passthru.Get()[SaveNum-1] = '\0'; 				Passthru.Apply(); 			}  			// Throw away empty string. 			if (SaveNum == 1) 			{ 				A.Data.Empty(); 			} 		} 	} 	else 	{ 		bool  SaveUCS2Char = Ar.IsForcingUnicode() || !FCString::IsPureAnsi(*A); 		int32 Num        = A.Data.Num(); 		int32 SaveNum    = SaveUCS2Char ? -Num : Num;  		Ar << SaveNum;  		A.Data.CountBytes( Ar );  		if (SaveNum) 		{ 			if (SaveUCS2Char) 			{ 				// TODO - This is creating a temporary in order to byte-swap.  Need to think about how to make this not necessary. 				#if !PLATFORM_LITTLE_ENDIAN 					FString  ATemp  = A; 					FString& A      = ATemp; 					INTEL_ORDER_TCHARARRAY(A.Data.GetData()); 				#endif  				Ar.Serialize((void*)StringCast<UCS2CHAR>(A.Data.GetData(), Num).Get(), sizeof(UCS2CHAR)* Num); 			} 			else 			{ 				Ar.Serialize((void*)StringCast<ANSICHAR>(A.Data.GetData(), Num).Get(), sizeof(ANSICHAR)* Num); 			} 		} 	}  	return Ar; }

注意，ue4,发送和接收数据都是用这段代码，Ar.IsLoading()为true代表接收数据，否则为发送数据

文章来源: ue4同c#通信时的中文乱码问题

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