UE5通过C++实现TcpSocket连接

在 Unreal Engine 5 的 C++ 项目中，实现一个具备消息监听、心跳检测和断线重连功能的 TCP 客户端，可以参考以下完整示例。

准备工作

1、模块依赖

在 YourModule.Build.cs 文件中，添加对 Sockets 和 Networking 模块的依赖：

PublicDependencyModuleNames.AddRange(new string[] {"Core","CoreUObject","Engine","Sockets","Networking"
});

2、包含头文件

在相关的 .h 文件中，包含必要的头文件：

#include "Networking.h"
#include "Sockets.h"
#include "SocketSubsystem.h"
#include "IPAddress.h"
#include "HAL/Runnable.h"
#include "HAL/RunnableThread.h"
#include "TimerManager.h"

TcpClient.h

#pragma once#include "CoreMinimal.h"
#include "HAL/Runnable.h"
#include "HAL/RunnableThread.h"
#include "Sockets.h"
#include "SocketSubsystem.h"
#include "TimerManager.h"DECLARE_DELEGATE_OneParam(FOnTcpConnected, bool /*bSuccess*/);
DECLARE_DELEGATE_OneParam(FOnTcpMessage, const TArray<uint8>& /*Data*/);
DECLARE_DELEGATE(FOnTcpDisconnected);class FTcpClient : public FRunnable
{
public:FTcpClient(const FString& InIp, int32 InPort, float InHeartbeatInterval = 5.0f);virtual ~FTcpClient();void Start();void StopClient();bool Send(const TArray<uint8>& Data);FOnTcpConnected OnConnected;FOnTcpMessage   OnMessage;FOnTcpDisconnected OnDisconnected;virtual bool Init() override;virtual uint32 Run() override;virtual void Stop() override;virtual void Exit() override;private:bool TryConnect();void SendHeartbeat();void StartHeartbeat();void StopHeartbeat();FString ServerIp;int32   ServerPort;float   HeartbeatInterval;FSocket*       Socket;FRunnableThread* Thread;FThreadSafeBool bRunThread;FThreadSafeBool bConnected;FTimerHandle HeartbeatTimerHandle;
};

TcpClient.cpp

#include "TcpClient.h"
#include "HAL/PlatformProcess.h"
#include "Async/Async.h"
#include "Engine/World.h"
#include "TimerManager.h"FTcpClient::FTcpClient(const FString& InIp, int32 InPort, float InHeartbeatInterval): ServerIp(InIp), ServerPort(InPort), HeartbeatInterval(InHeartbeatInterval), Socket(nullptr), Thread(nullptr), bRunThread(false), bConnected(false)
{
}FTcpClient::~FTcpClient()
{StopClient();
}void FTcpClient::Start()
{if (Thread == nullptr){bRunThread = true;Thread = FRunnableThread::Create(this, TEXT("TcpClientThread"));}
}void FTcpClient::StopClient()
{bRunThread = false;StopHeartbeat();if (Thread){Thread->Kill(true);delete Thread;Thread = nullptr;}if (Socket){Socket->Close();ISocketSubsystem::Get(PLATFORM_SOCKETSUBSYSTEM)->DestroySocket(Socket);Socket = nullptr;}
}bool FTcpClient::Init()
{return TryConnect();
}uint32 FTcpClient::Run()
{TArray<uint8> RecvBuffer;RecvBuffer.SetNumUninitialized(1024);while (bRunThread){if (bConnected){int32 BytesRead = 0;if (Socket->Recv(RecvBuffer.GetData(), RecvBuffer.Num(), BytesRead)){if (BytesRead > 0){TArray<uint8> Data;Data.Append(RecvBuffer.GetData(), BytesRead);OnMessage.ExecuteIfBound(Data);}}else{bConnected = false;OnDisconnected.ExecuteIfBound();Socket->Close();ISocketSubsystem::Get(PLATFORM_SOCKETSUBSYSTEM)->DestroySocket(Socket);Socket = nullptr;StopHeartbeat();}}else{FPlatformProcess::Sleep(3.0f);if (TryConnect()){bConnected = true;OnConnected.ExecuteIfBound(true);StartHeartbeat();}}}return 0;
}void FTcpClient::Stop()
{bRunThread = false;
}void FTcpClient::Exit()
{
}bool FTcpClient::TryConnect()
{Socket = ISocketSubsystem::Get(PLATFORM_SOCKETSUBSYSTEM)->CreateSocket(NAME_Stream, TEXT("TcpClientSocket"), false);Socket->SetNonBlocking(true);TSharedRef<FInternetAddr> Addr = ISocketSubsystem::Get(PLATFORM_SOCKETSUBSYSTEM)->CreateInternetAddr();bool bIsValid;Addr->SetIp(*ServerIp, bIsValid);Addr->SetPort(ServerPort);if (!bIsValid) return false;bool bOk = Socket->Connect(*Addr);if (bOk){bConnected = true;OnConnected.ExecuteIfBound(true);StartHeartbeat();}return bOk;
}bool FTcpClient::Send(const TArray<uint8>& Data)
{if (bConnected && Socket){int32 BytesSent = 0;return Socket->Send(Data.GetData(), Data.Num(), BytesSent);}return false;
}void FTcpClient::SendHeartbeat()
{FString HeartbeatMsg = TEXT("HEARTBEAT");TArray<uint8> Data;Data.Append((uint8*)TCHAR_TO_UTF8(*HeartbeatMsg), HeartbeatMsg.Len());Send(Data);
}void FTcpClient::StartHeartbeat()
{if (GWorld){GWorld->GetTimerManager().SetTimer(HeartbeatTimerHandle, [this](){SendHeartbeat();}, HeartbeatInterval, true);}
}void FTcpClient::StopHeartbeat()
{if (GWorld){GWorld->GetTimerManager().ClearTimer(HeartbeatTimerHandle);}
}

使用示例

在某个 Actor 中使用：

// .h
TUniquePtr<FTcpClient> TcpClient;// .cpp BeginPlay
TcpClient = MakeUnique<FTcpClient>(TEXT("127.0.0.1"), 7777);
TcpClient->OnConnected.BindLambda([](bool bOk){UE_LOG(LogTemp, Log, TEXT("Connected: %s"), bOk ? TEXT("成功") : TEXT("失败"));
});
TcpClient->OnMessage.BindLambda([](const TArray<uint8>& Data){FString Msg(UTF8_TO_TCHAR(Data.GetData()));UE_LOG(LogTemp, Log, TEXT("Received: %s"), *Msg);
});
TcpClient->OnDisconnected.BindLambda([](){UE_LOG(LogTemp, Warning, TEXT("已断线，正在重连…"));
});
TcpClient->Start();// 发送消息
TArray<uint8> Out;
FString ToSend = TEXT("Hello UE5");
Out.Append((uint8*)TCHAR_TO_UTF8(*ToSend), ToSend.Len());
TcpClient->Send(Out);

这样，你就拥有了一个在独立线程中运行、自动重连、带有心跳检测，并通过委托通知主线程的 TCP 客户端类，可以直接嵌入到 UE5 项目中使用。

注意

在 Unreal Engine 中，FSocket::GetConnectionState() 并不是通过底层 TCP 协议实时探测对端是否已关闭连接，而只是返回之前记录的“连接状态”（ESocketConnectionState）。如果服务器在另一端直接关闭（例如进程退出或调用 Close()），而客户端未主动调用 Disconnect()、也未在套接字上执行任何 I/O 操作，那么 GetConnectionState() 会继续报告 SCS_Connected。这是因为：

1. TCP 的连接关闭需要通过 四次挥手（FIN/ACK）握手 完成，若一端不正确地发起或响应 FIN，另一端的状态不会变成 CLOSED。

2. UE 中的 GetConnectionState() 并不会自动触发 I/O，也不依赖 OS 的 keep-alive 机制，它只反映最初的连接结果。

3. 要真正探测断线，需要在套接字上执行一次 Recv()（或 Send()）才会返回错误或 0 字节读取。