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数字孪生

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Async Http Request 模块

参考:【UE4 C++】HTTP 异步请求 json 数据和下载文件

Async Http Request 用于构建虚幻引擎与网络API之间的沟通，基于HttpRequest，向指定url的API发送信息

方法:

  1. 基于UBlueprintAsyncActionBase新建C++类

  2. 在build.cs中开启"HTTP" ,"Json","JsonUtilities"模块

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    PublicDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", "Engine", "InputCore" ,"UMG" ,"Niagara" , "NiagaraCore"});
            
    PrivateDependencyModuleNames.AddRange(new string[] { "HTTP" ,"Json","JsonUtilities"});

  3. 在新建C++类中构建BlueprintType结构体，用于存储数据

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    USTRUCT(BlueprintType)
    struct F[结构体名称]
    {
        GENERATED_BODY()
        ...
    };

  4. 在类外建立动态单参数多播委托，以建立C++与蓝图之间的联系

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    DECLARE_DYNAMIC_MULTICAST_DELEGATE_OneParam(F[委托名],参数类,参数名);

  5. 在类内建立静态工厂函数，以暴露给蓝图使用

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    UFUNCTION(BlueprintCallable,Category="AsyncHttp",meta=(BlueprintInternalUseOnly="true"))
    static UAsyncHttpRequest* AsyncHttpURLRequest(const FString& Url);

  6. 在类内建立委托节点，已发送信息

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    UPROPERTY(BlueprintAssignable)
    FPosRequestCompleteDelegate PosOnSucceeded;

    UPROPERTY(BlueprintAssignable)
    FPosRequestCompleteDelegate PosOnFailed;

  7. 在cpp中实现函数，发送请求，并编写接受信息实现

完整代码:

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

#pragma once

#include "CoreMinimal.h"
#include "Kismet/BlueprintAsyncActionBase.h"
#include "Interfaces//IHttpRequest.h"
#include "AsyncHttpRequest.generated.h"

/**
 *	FPositionItem 用于承载获取的纬度与经度
 */
USTRUCT(BlueprintType)
struct FPositionItem
{
	GENERATED_BODY()

	FPositionItem(){}
	FPositionItem(FString _Latitude,FString _Longitude):Latitude(_Latitude),Longitude(_Longitude){}

	UPROPERTY(BlueprintReadOnly)
	FString Latitude;

	UPROPERTY(BlueprintReadOnly)
	FString Longitude;
};

// 定义委托 以返回纬度与经度
DECLARE_DYNAMIC_MULTICAST_DELEGATE_OneParam(FPosRequestCompleteDelegate,const FPositionItem&,Positon);

/**
 * 
 */
UCLASS()
class SCHOOL_API UAsyncHttpRequest : public UBlueprintAsyncActionBase
{
	GENERATED_BODY()

public:
	UAsyncHttpRequest();

	UFUNCTION(BlueprintCallable,Category="AsyncHttp",meta=(BlueprintInternalUseOnly="true"))
	static UAsyncHttpRequest* AsyncHttpURLRequest(const FString& Url);

	void HttpRequestStar(const FString& Url);
	void HttpRequest_PosRecHandle(FHttpRequestPtr Request,FHttpResponsePtr Response,bool bWasSuccess);
	
	// 委托以输出结果 
	UPROPERTY(BlueprintAssignable)
	FPosRequestCompleteDelegate PosOnSucceeded;

	UPROPERTY(BlueprintAssignable)
	FPosRequestCompleteDelegate PosOnFailed;
	
};

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


#include "AsyncHttpRequest.h"
#include "HttpModule.h"
#include "Interfaces/IHttpResponse.h"

UAsyncHttpRequest::UAsyncHttpRequest()
{
	if(HasAnyFlags(RF_ClassDefaultObject) == false)
	{
		AddToRoot(); // 防止自动GC
	}
}

// 静态工厂
UAsyncHttpRequest* UAsyncHttpRequest::AsyncHttpURLRequest(const FString& Url)
{
	UAsyncHttpRequest* AsyncHttpRequest = NewObject<UAsyncHttpRequest>();
	AsyncHttpRequest->HttpRequestStar(Url);
	return AsyncHttpRequest;
}

// 开始请求
void UAsyncHttpRequest::HttpRequestStar(const FString& Url)
{
	TSharedRef<IHttpRequest,ESPMode::ThreadSafe> Request = FHttpModule::Get().CreateRequest();
	Request->SetVerb("GET");
	Request->SetURL(Url);
	
	Request->OnProcessRequestComplete().BindUObject(this,&UAsyncHttpRequest::HttpRequest_PosRecHandle); // 请求回调
	Request->ProcessRequest();
}

// 回调函数
void UAsyncHttpRequest::HttpRequest_PosRecHandle(FHttpRequestPtr Request, FHttpResponsePtr Response, bool bWasSuccess)
{
	if(bWasSuccess && Response.IsValid() && EHttpResponseCodes::IsOk(Response->GetResponseCode()))
	{
		TSharedPtr<FJsonObject> JsonObj;
		TSharedRef<TJsonReader<>> JsonReader = TJsonReaderFactory<>::Create(Response->GetContentAsString()); // 解析Json

		// 反序列化
		if(FJsonSerializer::Deserialize(JsonReader,JsonObj))
		{
			FString PosString;
			if(JsonObj->TryGetStringField(TEXT("rectangle"),PosString))
			{
				FPositionItem GetPosItem;
				bool IsReadSec = false;
				for(const auto& c : PosString)
				{
					if(c == ',') IsReadSec = true;
					else if(c == ';') break;
					else if(IsReadSec) GetPosItem.Latitude += c;
					else GetPosItem.Longitude += c;
				}

				// GEngine->AddOnScreenDebugMessage(-1,10.f,FColor::Cyan,PosString);
				PosOnSucceeded.Broadcast(GetPosItem); // 成功执行并广播
				RemoveFromRoot();
				return ;
			}
		}
	}

	PosOnFailed.Broadcast({});
	RemoveFromRoot(); // 手动GC
}