【UE4 C++】HTTP 異步請求 json 數據和下載文件

• 前言
  • 一般做個數據請求、或者下載文件可以用到。當然也可以使用webSocket,或第三方庫，都可以，開心就好 ^_
  • 本文只是用了 UBlueprintAsyncActionBase，也可以用多線程
  • 本文沒有實現上傳文件、且省略了post請求的使用
  • 算是稍微重新整理吧
• 引擎版本：4.26.2
• 原文地址

---

准備工作

• .Build.cs 添加 HTTP、Json 模塊

  PrivateDependencyModuleNames.AddRange(new string[] { "HTTP", "Json" });
  

• 創建繼承 UBlueprintAsyncActionBase 的類

• Json 解析，參考 【UE4 C++】 解析與構建 Json 數據

• 異步藍圖節點，參考 【UE4 C++】異步藍圖節點

請求 json 數據

• 請求的 json 格式,url 為 https://docs.tenapi.cn/zhihuresou.html#請求示例

  {
    "data": 200,
    "list": [
      {
        "name": "notability",
        "query": "Notability 年費訂閱制",
        "url": "https://www.zhihu.com/search?q=notability&utm_content=search_hot&type=content"
      },
      {
        "name": "馬斯克",
        "query": "馬斯克中文發《七步詩》",
        "url": "https://www.zhihu.com/search?q=%E9%A9%AC%E6%96%AF%E5%85%8B&utm_content=search_hot&type=content"
      },
      ...
  }
  

• 主要代碼

  • 頭文件

    //@ https://www.cnblogs.com/shiroe/p/15500780.html
    #pragma once
    #include "CoreMinimal.h"
    #include "Kismet/BlueprintAsyncActionBase.h"
    #include "Interfaces/IHttpRequest.h"
    #include "AsyncHttpObject.generated.h"
    
    USTRUCT(BlueprintType)
    struct FNewsItem {
    	 GENERATED_USTRUCT_BODY()
    
    	FNewsItem() {}
    	FNewsItem(FString _key, FString _title, FString _url)
    		: key(_key), title(_title), url(_url) {}
    	UPROPERTY(BlueprintReadOnly)
    		FString key;
    	UPROPERTY(BlueprintReadOnly)
    		FString title;
    	UPROPERTY(BlueprintReadOnly)
    		FString url;
    };
    
    // 定義委托,作為返回
    DECLARE_DYNAMIC_MULTICAST_DELEGATE_OneParam(FRequestCompleteDelegate, const TArray<FNewsItem>&, Data); //注意此處的參數類型
    
    UCLASS()
    class RUBIKSCUBE_API UAsyncHttpObject : public UBlueprintAsyncActionBase
    {
    	GENERATED_BODY()
    		
    public:
    	UAsyncHttpObject();
    	// 自定義的異步藍圖節點
    	UFUNCTION(BlueprintCallable, Category = "AsyncHttp", meta=( BlueprintInternalUseOnly="true" ))
    		static UAsyncHttpObject* AsyncHttpURLRequest(const FString& url);
    	
    	void HttpRequestStar(const FString& url);
    	void HttpRequest_RecHandle(FHttpRequestPtr request, FHttpResponsePtr response, bool bWasSuccessful);
    
    	//輸出節點
    	UPROPERTY(BlueprintAssignable)
    		FRequestCompleteDelegate OnSucceeded;
    
    	//輸出節點
    	UPROPERTY(BlueprintAssignable)
    		FRequestCompleteDelegate OnFailed;
    
    };
    

  • cpp

    //@ https://www.cnblogs.com/shiroe/p/15500780.html
    #include "AsyncHttpObject.h"
    #include "HttpModule.h"
    #include "Interfaces/IHttpResponse.h"
    
    UAsyncHttpObject::UAsyncHttpObject()
    {
    	if (HasAnyFlags(RF_ClassDefaultObject) == false)
    	{
    		AddToRoot(); //防止自動GC
    	}
    }
    
    UAsyncHttpObject* UAsyncHttpObject::AsyncHttpURLRequest( const FString& url) {
    	UAsyncHttpObject* AsyncHttpObject = NewObject<UAsyncHttpObject>();
    	AsyncHttpObject->HttpRequestStar(url);	
    	return AsyncHttpObject;
    }
    
    //開始請求
    void UAsyncHttpObject::HttpRequestStar(const FString& url)
    {
    	TSharedRef<IHttpRequest, ESPMode::ThreadSafe> request = FHttpModule::Get().CreateRequest();
    	request->SetVerb("GET");
    	request->SetURL(url);
    	//request->SetHeader(TEXT("Content-Type"), TEXT("application/json;charset=utf-8"));
    	//request->SetTimeout(200);
    	//request->SetContentAsString(requestJsonStr); POST時候用
    	//request->OnRequestProgress().BindUObject() 綁定進度
    	request->OnProcessRequestComplete().BindUObject(this, &UAsyncHttpObject::HttpRequest_RecHandle); //請求回調
    	request->ProcessRequest();
    }
    //請求回調
    void UAsyncHttpObject::HttpRequest_RecHandle(FHttpRequestPtr request, FHttpResponsePtr response, bool bWasSuccessful) {
    	
    
    	if (bWasSuccessful && response.IsValid() && EHttpResponseCodes::IsOk(response->GetResponseCode())) {
    		TSharedPtr<FJsonObject> jsonObj;
    		TSharedRef<TJsonReader<>> JsonReader = TJsonReaderFactory<>::Create(response->GetContentAsString());
    
    		if (FJsonSerializer::Deserialize(JsonReader,jsonObj)) {
    			const TArray< TSharedPtr<FJsonValue> >* dataList;
    			if (jsonObj->TryGetArrayField(TEXT("list"), dataList)) // 獲取數組
    			{
    				TArray<FNewsItem> newsList;
    				for (TSharedPtr<FJsonValue> item : *dataList)
    				{
    					TSharedPtr<FJsonObject>itemObjet = item->AsObject();
    
    					newsList.Add(FNewsItem(
    						itemObjet->GetStringField(TEXT("name")),
    						itemObjet->GetStringField(TEXT("query")),
    						itemObjet->GetStringField(TEXT("url"))
    						));
    				}
    				OnSucceeded.Broadcast(newsList); // 成功的執行
    				RemoveFromRoot();
    				return;
    			}
    		}
    	}
    	OnFailed.Broadcast({}); // 失敗的執行
    	RemoveFromRoot();
    }
    

• 藍圖部分和效果#

  

異步下載文件

• 主要代碼 (本文地址)

  • 頭文件

    //@ https://www.cnblogs.com/shiroe/p/15500780.html
    DECLARE_DYNAMIC_MULTICAST_DELEGATE_ThreeParams(FDownloadProgressDelegate,
    const int32&, ReceivedDataInBytes,
    const int32&, TotalDataInBytes,
    const TArray<uint8>&, BinaryData
    );
    DECLARE_DYNAMIC_MULTICAST_DELEGATE(FDownloadDelegate);
    
    // 異步下載文件
    	UFUNCTION(BlueprintCallable, Category = "AsyncHttp", meta = (BlueprintInternalUseOnly = "true"))
    		static UAsyncHttpObject* AsyncHttpDownload(const FString& url);
    
    	void DownloadRequestStart(const FString& url);
    	void DownloadRequestHandle(FHttpRequestPtr request, FHttpResponsePtr response, bool bWasSuccessful);
    	void DownloadProgress(FHttpRequestPtr request, int32 bytesSent, int32 bytesReceived);
    
    	//輸出節點
    	UPROPERTY(BlueprintAssignable)
    		FDownloadProgressDelegate OnProgressUpdate; //最好把有參數的放在前面，不然參數在藍圖節點有時候被吃掉了
    
    	//輸出節點
    	UPROPERTY(BlueprintAssignable)
    		FDownloadDelegate OnSucc;
    
    	//輸出節點
    	UPROPERTY(BlueprintAssignable)
    		FDownloadDelegate OnFailed;
    

  • cpp

    //@ https://www.cnblogs.com/shiroe/p/15500780.html
    // 異步下載
    UAsyncHttpObject* UAsyncHttpObject::AsyncHttpDownload(const FString& url)
    {
    	UAsyncHttpObject* AsyncHttpObject = NewObject<UAsyncHttpObject>();
    	AsyncHttpObject->DownloadRequestStart(url);
    	return AsyncHttpObject;
    }
    
    //開始請求下載
    void UAsyncHttpObject::DownloadRequestStart(const FString& url)
    {
    	TSharedRef<IHttpRequest, ESPMode::ThreadSafe> request = FHttpModule::Get().CreateRequest();
    	request->SetVerb("GET");
    	request->SetURL(url);
    	request->OnProcessRequestComplete().BindUObject(this, &UAsyncHttpObject::DownloadRequestHandle); //請求回調
    	request->OnRequestProgress().BindUObject(this, &UAsyncHttpObject::DownloadProgress);// 下載進度
    	request->ProcessRequest();
    
    	RemoveFromRoot(); // 手動GC
    }
    
    ////請求回調
    void UAsyncHttpObject::DownloadRequestHandle(FHttpRequestPtr request, FHttpResponsePtr response, bool bWasSuccessful)
    {
    	RemoveFromRoot();
    	
    
    	if (bWasSuccessful && response.IsValid() && EHttpResponseCodes::IsOk(response->GetResponseCode()))
    	{
    		if (response->GetContentLength() > 0) {
    			TArray<uint8> EmptyData;
    			OnProgressUpdate.Broadcast(response->GetContentLength(), response->GetContentLength(), EmptyData);
    		}	
    		
    		FString FileSavePath = FPaths::ProjectDir()+"/download/gameplay.png";  
    		FString Path, Filename, Extension;
    		FPaths::Split(FileSavePath, Path, Filename, Extension);
    		IPlatformFile& PlatformFile = FPlatformFileManager::Get().GetPlatformFile();	
    		
    		if (!PlatformFile.DirectoryExists(*Path))
    		{
    			if (!PlatformFile.CreateDirectoryTree(*Path))
    			{
    				UE_LOG(LogTemp, Error, TEXT("Create Directory Failed!"));
    				OnFailed.Broadcast();
    				return;
    			}
    		}
    
    		IFileHandle* FileHandle = PlatformFile.OpenWrite(*FileSavePath);
    		if (FileHandle)
    		{
    			FileHandle->Write(response->GetContent().GetData(), response->GetContentLength());
    			delete FileHandle;
    			OnSucc.Broadcast();
    			return;
    		}
    		else {
    			UE_LOG(LogTemp, Error, TEXT("Save File Failed!"));
    			OnFailed.Broadcast();
    			return;
    		}
    			
    	}		
    	UE_LOG(LogTemp, Error, TEXT("download File Failed!"));
    	OnFailed.Broadcast();
    	return;
    }
    
    // 下載進度
    void UAsyncHttpObject::DownloadProgress(FHttpRequestPtr request, int32 bytesSent, int32 bytesReceived)
    {
    	if (request->GetResponse()->GetContentLength() > 0)
    	{
    		TArray<uint8> EmptyData;
    		OnProgressUpdate.Broadcast(bytesReceived, request->GetResponse()->GetContentLength(),EmptyData);
    	}
    }
    

• 藍圖及效果