UE4 UDP通信

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用c++创建两个Actor类，分别为UDPSend(发送)   和  UDPRecive（接收）

代码如下：

UDPSend.h

// Fill out your copyright notice in the Description page of Project Settings.

#pragma once
#include "Networking.h"
#include "GameFramework/Actor.h"
#include "UDPSend.generated.h"

UCLASS()
class UDP_API AUDPSend : public AActor
{
	GENERATED_BODY()
	
public:	
	// Sets default values for this actor's properties
	AUDPSend();

	// Called when the game starts or when spawned
	virtual void BeginPlay() override;
	
	// Called every frame
	virtual void Tick( float DeltaSeconds ) override;

public:

	bool IsUDP;

	UFUNCTION(BlueprintCallable, Category = "UDP")
		bool RamaUDPSender_SendString(FString ToSend);
public:

	TSharedPtr<FInternetAddr> RemoteAddr;
	FSocket* SenderSocket;
	UFUNCTION(BlueprintCallable, Category = "UDP")
		bool StartUDPSender(const FString& YourChosenSocketName, const FString& TheIP, const int32 ThePort, bool UDP);

public:
	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "UDP")
		bool ShowOnScreenDebugMessages;


	//ScreenMsg
	FORCEINLINE void ScreenMsg(const FString& Msg)
	{
		if (!ShowOnScreenDebugMessages) return;
		GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, *Msg);
	}
	FORCEINLINE void ScreenMsg(const FString& Msg, const float Value)
	{
		if (!ShowOnScreenDebugMessages) return;
		GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, FString::Printf(TEXT("%s %f"), *Msg, Value));
	}
	FORCEINLINE void ScreenMsg(const FString& Msg, const FString& Msg2)
	{
		if (!ShowOnScreenDebugMessages) return;
		GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, FString::Printf(TEXT("%s %s"), *Msg, *Msg2));
	}


public:

	/** Called whenever this actor is being removed from a level */
	virtual void EndPlay(const EEndPlayReason::Type EndPlayReason) override;
};

UDPSend.cpp

// Fill out your copyright notice in the Description page of Project Settings.

#include "UDP.h"
#include "UDPSend.h"


// Sets default values
AUDPSend::AUDPSend()
{
 	// Set this actor to call Tick() every frame.  You can turn this off to improve performance if you don't need it.
	PrimaryActorTick.bCanEverTick = true;

	SenderSocket = NULL;

	ShowOnScreenDebugMessages = true;
}

// Called when the game starts or when spawned
void AUDPSend::BeginPlay()
{
	Super::BeginPlay();
	
}

// Called every frame
void AUDPSend::Tick( float DeltaTime )
{
	Super::Tick( DeltaTime );

}

void AUDPSend::EndPlay(const EEndPlayReason::Type EndPlayReason)
{
	Super::EndPlay(EndPlayReason);
	//~~~~~~~~~~~~~~~~

	if (SenderSocket) //Clear all sockets!
	{
		SenderSocket->Close();
		ISocketSubsystem::Get(PLATFORM_SOCKETSUBSYSTEM)->DestroySocket(SenderSocket);
	}
}



bool AUDPSend::RamaUDPSender_SendString(FString ToSend)                 //发送消息处理
{
	if (!SenderSocket)
	{
		ScreenMsg("No sender socket");
		return false; 
	}
	//~~~~~~~~~~~~~~~~
	//发送消息
	int32 BytesSent = 0;
	FString serialized = ToSend;
	TCHAR *serializedChar = serialized.GetCharArray().GetData();
	int32 size = FCString::Strlen(serializedChar);
	int32 sent = 0;
	//SenderSocket->SendTo(Writer.GetData(), Writer.Num(), BytesSent, *RemoteAddr);
	SenderSocket->SendTo((uint8*)TCHAR_TO_UTF8(serializedChar), size, BytesSent, *RemoteAddr);//发送给远端地址

	if (BytesSent <= 0)
	{
		const FString Str = "Socket is valid but the receiver received 0 bytes, make sure it is listening properly!";
		UE_LOG(LogTemp, Error, TEXT("%s"), *Str);
		ScreenMsg(Str);
		return false;
	}

	ScreenMsg("UDP Send Succcess! INFO Sent = ", ToSend);

	return true;
}


bool AUDPSend::StartUDPSender(const FString & YourChosenSocketName, const FString & TheIP, const int32 ThePort, bool UDP)///////////初始化远端IP 发送信息前
{
	//FIPv4Endpoint Endpoint(FIPv4Address::Any, 6789);
	//Create Remote Address.
	RemoteAddr = ISocketSubsystem::Get(PLATFORM_SOCKETSUBSYSTEM)->CreateInternetAddr();

	bool bIsValid;
	RemoteAddr->SetIp(*TheIP, bIsValid);
	RemoteAddr->SetPort(ThePort);

	if (!bIsValid)
	{
		ScreenMsg("Rama UDP Sender>> IP address was not valid!", TheIP);
		return false;
	}


	SenderSocket = FUdpSocketBuilder(*YourChosenSocketName)
		.AsReusable()
		.WithBroadcast()/////////////广播
		.WithSendBufferSize(2 * 1024 * 1024)
		//.BoundToEndpoint(Endpoint)
		;


	//check(SenderSocket->GetSocketType() == SOCKTYPE_Datagram);

	//Set Send Buffer Size
	int32 SendSize = 2 * 1024 * 1024;
	SenderSocket->SetSendBufferSize(SendSize, SendSize);
	SenderSocket->SetReceiveBufferSize(SendSize, SendSize);
	if (bIsValid)
	{
		bIsValid = true;
	}
	return bIsValid;

}

UDPRecive.h

// Fill out your copyright notice in the Description page of Project Settings.

#pragma once
#include "Networking.h"
#include "GameFramework/Actor.h"
#include "UDPRecive.generated.h"

UCLASS()
class UDP_API AUDPRecive : public AActor
{
	GENERATED_BODY()
	
public:	
	// Sets default values for this actor's properties
	AUDPRecive();

	// Called when the game starts or when spawned
	virtual void BeginPlay() override;
	
	// Called every frame
	virtual void Tick( float DeltaSeconds ) override;

	
public:
	FSocket* ListenSocket;

	FUdpSocketReceiver* UDPReceiver = nullptr;


	UFUNCTION(BlueprintCallable, Category = "UDP")
		void StartUDPReceiver(const FString& YourChosenSocketName, const FString& TheIP, const int32 ThePort, bool& success);
	
	UFUNCTION(BlueprintPure, Category = "UDP")
		void DataRecv(FString& str, bool& success);

	//ScreenMsg
	FORCEINLINE void ScreenMsg(const FString& Msg)
	{
		GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, *Msg);
	}
	FORCEINLINE void ScreenMsg(const FString& Msg, const float Value)
	{
		GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, FString::Printf(TEXT("%s %f"), *Msg, Value));
	}
	FORCEINLINE void ScreenMsg(const FString& Msg, const FString& Msg2)
	{
		GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, FString::Printf(TEXT("%s %s"), *Msg, *Msg2));
	}


public:

	/** Called whenever this actor is being removed from a level */
	virtual void EndPlay(const EEndPlayReason::Type EndPlayReason) override; 

};

UDPRecive.cpp

// Fill out your copyright notice in the Description page of Project Settings.

#include "UDP.h"
#include "UDPRecive.h"


// Sets default values
AUDPRecive::AUDPRecive()
{
 	// Set this actor to call Tick() every frame.  You can turn this off to improve performance if you don't need it.
	PrimaryActorTick.bCanEverTick = true;

	ListenSocket = NULL;
}

// Called when the game starts or when spawned
void AUDPRecive::BeginPlay()
{
	Super::BeginPlay();
	
}

// Called every frame
void AUDPRecive::Tick( float DeltaTime )
{
	Super::Tick( DeltaTime );

}

void AUDPRecive::EndPlay(const EEndPlayReason::Type EndPlayReason)
{
	Super::EndPlay(EndPlayReason);
	//~~~~~~~~~~~~~~~~

	delete UDPReceiver;
	UDPReceiver = nullptr;

	//Clear all sockets!
	//      makes sure repeat plays in Editor dont hold on to old sockets!
	if (ListenSocket)
	{
		ListenSocket->Close();
		ISocketSubsystem::Get(PLATFORM_SOCKETSUBSYSTEM)->DestroySocket(ListenSocket);
	}
}

//Start UDP Receiver
void AUDPRecive::StartUDPReceiver(const FString& YourChosenSocketName, const FString& TheIP, const int32 ThePort, bool& success) // 接收器初始化  接收信息前
{

	TSharedRef<FInternetAddr> targetAddr = ISocketSubsystem::Get(PLATFORM_SOCKETSUBSYSTEM)->CreateInternetAddr();
	FIPv4Address Addr;
	FIPv4Address::Parse(TheIP, Addr);

	//Create Socket
	FIPv4Endpoint Endpoint(FIPv4Address::Any, ThePort);  //所有ip地址本地
														 //FIPv4Endpoint Endpoint(Addr, ThePort);                 //指定ip地址
	ListenSocket = FUdpSocketBuilder(*YourChosenSocketName)
		.AsNonBlocking()
		.AsReusable()
		.BoundToEndpoint(Endpoint)
		.WithReceiveBufferSize(2 * 1024 * 1024)

		;
	//BUFFER SIZE
	int32 BufferSize = 2 * 1024 * 1024;
	ListenSocket->SetSendBufferSize(BufferSize, BufferSize);
	ListenSocket->SetReceiveBufferSize(BufferSize, BufferSize);

	if (!ListenSocket)
	{
		ScreenMsg("No socket");
		success = false;

	}
	if (ListenSocket)
	{
		ScreenMsg("The receiver is initialized");
		success = true;
	}

	//return true;
}

void AUDPRecive::DataRecv(FString& str, bool& success)              //接收消息处理
{

	if (!ListenSocket)
	{
		ScreenMsg("No sender socket");
		success = false;
		//return success;
	}
	TSharedRef<FInternetAddr> targetAddr = ISocketSubsystem::Get(PLATFORM_SOCKETSUBSYSTEM)->CreateInternetAddr();
	TArray<uint8> ReceivedData;//定义一个接收器
	uint32 Size;
	if (ListenSocket->HasPendingData(Size))
	{
		success = true;
		str = "";
		uint8 *Recv = new uint8[Size];
		int32 BytesRead = 0;

		ReceivedData.SetNumUninitialized(FMath::Min(Size, 65507u));
		ListenSocket->RecvFrom(ReceivedData.GetData(), ReceivedData.Num(), BytesRead, *targetAddr);//创建远程接收地址
		char ansiiData[1024];
		memcpy(ansiiData, ReceivedData.GetData(), BytesRead);//拷贝数据到接收器
		ansiiData[BytesRead] = 0;                            //判断数据结束
		FString debugData = ANSI_TO_TCHAR(ansiiData);         //字符串转换
		str = debugData;
		// memset(ansiiData,0,1024);//清空 

	}
	else
	{
		success = false;
	}
	//return success;
}

最后在Bulid.cs里面增加如下代码：

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

然后把工程文件关闭重新生成一下，这个是解决Networking报错的方法。

接着用蓝图继承以上两个类，在蓝图里调用C++开放的方法，拖入场景进行实例化。

参考：https://wiki.unrealengine.com/UDP_Socket_Sender_Receiver_From_One_UE4_Instance_To_Another