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http网络编程在ue5中实现

需求：在unreal中实现下载功能，输入相关url网址，本地文件夹存入相应文件。

一、代码示例

1.Build.cs需要新增Http模块，样例如下。

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

2.RuntimeFilesDownloaderLibrary.h文件

// Fill out your copyright notice in the Description page of Project Settings.#pragma once#include "CoreMinimal.h"
#include "UObject/Object.h"
#include "Interfaces/IHttpRequest.h"
#include "RuntimeFilesDownloaderLibrary.generated.h"UENUM(BlueprintType, Category = "Runtime Files Downloader")
enum DownloadResult
{SuccessDownloading UMETA(DisplayName = "Success"),DownloadFailed UMETA(DisplayName = "Download failed"),SaveFailed UMETA(DisplayName = "Save failed"),DirectoryCreationFailed UMETA(DisplayName = "Directory creation failed")
};
DECLARE_DYNAMIC_MULTICAST_DELEGATE_ThreeParams(FOnFilesDownloaderProgress, const int32, BytesSent, const int32, BytesReceived, const int32, ContentLength);DECLARE_DYNAMIC_MULTICAST_DELEGATE_OneParam(FOnFilesDownloaderResult, TEnumAsByte < DownloadResult >, Result);UCLASS()
class DOWNLOAD_API URuntimeFilesDownloaderLibrary : public UObject
{GENERATED_BODY()
public:UPROPERTY(BlueprintAssignable, Category = "Runtime Files Downloader")FOnFilesDownloaderProgress OnProgress;UPROPERTY(BlueprintAssignable, Category = "Runtime Files Downloader")FOnFilesDownloaderResult OnResult;UPROPERTY(BlueprintReadOnly, Category = "Runtime Files Downloader")FString FileURL;UPROPERTY(BlueprintReadOnly, Category = "Runtime Files Downloader")FString FileSavePath;UFUNCTION(BlueprintCallable, Category = "Runtime Files Downloader")static URuntimeFilesDownloaderLibrary* CreateDownloader();UFUNCTION(BlueprintCallable, Category = "Runtime Files Downloader")bool DownloadFile(const FString& URL, const FString& SavePath, float TimeOut = 5);
private:void OnProgress_Internal(FHttpRequestPtr Request, int32 BytesSent, int32 BytesReceived);void OnReady_Internal(FHttpRequestPtr Request, FHttpResponsePtr Response, bool bWasSuccessful);
};

3.RuntimeFilesDownloaderLibrary.cpp文件

#include "RuntimeFilesDownloaderLibrary.h"
#include "HttpModule.h"
#include "Interfaces/IHttpRequest.h"
#include "Interfaces/IHttpResponse.h"
//创建了一个URuntimeFilesDownloaderLibrary对象，并将其添加到根对象，防止系统自动回收
URuntimeFilesDownloaderLibrary* URuntimeFilesDownloaderLibrary::CreateDownloader()
{URuntimeFilesDownloaderLibrary* Downloader = NewObject<URuntimeFilesDownloaderLibrary>();Downloader->AddToRoot();return Downloader;
}bool URuntimeFilesDownloaderLibrary::DownloadFile(const FString& URL, const FString& SavePath, float TimeOut)
{if (URL.IsEmpty() || SavePath.IsEmpty() || TimeOut <= 0){return false;}FileURL = URL;FileSavePath = SavePath;/*ue4.27旧版本弃用下列方法*//*TSharedRef<IHttpRequest, ESPMode::ThreadSafe> HttpRequest = FHttpModule::Get().CreateRequest();*///4.27及以后使用如下方法TSharedPtr<IHttpRequest, ESPMode::ThreadSafe> HttpRequest = FHttpModule::Get().CreateRequest();HttpRequest->SetVerb("GET");HttpRequest->SetURL(FileURL);//HttpRequest->SetTimeout(TimeOut);//监听事件OnProcessRequestComplete绑定OnReady_Internal，OnRequestProgress绑定OnProgress_InternalHttpRequest->OnProcessRequestComplete().BindUObject(this, &URuntimeFilesDownloaderLibrary::OnReady_Internal);HttpRequest->OnRequestProgress().BindUObject(this, &URuntimeFilesDownloaderLibrary::OnProgress_Internal);// Process the requestHttpRequest->ProcessRequest();return true;
}//监听事件
void URuntimeFilesDownloaderLibrary::OnProgress_Internal(FHttpRequestPtr Request, int32 BytesSent, int32 BytesReceived)
{const FHttpResponsePtr Response = Request->GetResponse();if (Response.IsValid()){const int32 FullSize = Response->GetContentLength();OnProgress.Broadcast(BytesSent, BytesReceived, FullSize);}
}void URuntimeFilesDownloaderLibrary::OnReady_Internal(FHttpRequestPtr Request, FHttpResponsePtr Response,bool bWasSuccessful)
{
RemoveFromRoot();Request->OnProcessRequestComplete().Unbind();if (Response.IsValid() && EHttpResponseCodes::IsOk(Response->GetResponseCode()) && bWasSuccessful){//IPlatformFile& PlatformFile = FPlatformFileManager::Get().GetPlatformFile();// FString Path, Filename, Extension;FPaths::Split(FileSavePath, Path, Filename, Extension);//查看文件夹，没有则创建文件if (!PlatformFile.DirectoryExists(*Path)){if (!PlatformFile.CreateDirectoryTree(*Path)){OnResult.Broadcast(DirectoryCreationFailed);return;}}// 开启文件写入//通过PlatformFile.OpenWrite()函数打开文件句柄，以便将下载的数据写入文件中。函数的参数是一个TCHAR类型的字符串，表示文件的路径和文件名。//然后，检查句柄是否成功打开。如果句柄成功打开，就将HTTP请求响应中的数据通过FileHandle->Write()函数写入到文件中。IFileHandle* FileHandle = PlatformFile.OpenWrite(*FileSavePath);if (FileHandle){// FileHandle->Write(Response->GetContent().GetData(), Response->GetContentLength());// delete FileHandle;OnResult.Broadcast(SuccessDownloading);}else{OnResult.Broadcast(SaveFailed);}}else{OnResult.Broadcast(DownloadFailed);}
}

二、蓝图示例

该蓝图在关卡中调用，通过Event Begin Play事件监听行为，当按下

按钮，创建DOWNLOADER对象，并执行下载功能，下载时对下载行为进行监听，包括RESULT（Success，Download failed，Save failed，Directory creation failed四种下载结果)和以下三个数据信息：

· BytesSent 表示已发送的字节数，指示已经发送到服务器的字节数。

· BytesReceived 表示已接收的字节数，指示已从服务器接收到的字节数。

· FullSize 表示完整内容的长度，指示需要下载的文件的总字节数。

最后通过BytesReceived/FullSize计算出百分号数据，实现下载进度实时追踪，下载完成后RESULT枚举信息输出。

三、效果展示

在蓝图中输入url和save path相关信息，time out为响应时间设置。

下载过程实现监听，下载完成后输出RESULT枚举类型。

最后本地文件夹成功下载http文件。