【UE4 C++】HTTP 异步请求 json 数据和下载文件

前言
- 一般做个数据请求、或者下载文件可以用到。当然也可以使用webSocket,或第三方库，都可以，开心就好 ^_
- 本文只是用了 UBlueprintAsyncActionBase，也可以用多线程
- 本文没有实现上传文件、且省略了post请求的使用
- 算是稍微重新整理吧
引擎版本：4.26.2
原文地址

准备工作

.Build.cs 添加 HTTP、Json 模块

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

创建继承 UBlueprintAsyncActionBase 的类
Json 解析，参考【UE4 C++】解析与构建 Json 数据
异步蓝图节点，参考【UE4 C++】异步蓝图节点

请求 json 数据

请求的 json 格式,url 为 https://docs.tenapi.cn/zhihuresou.html#请求示例

{
  "data": 200,
  "list": [
    {
      "name": "notability",
      "query": "Notability 年费订阅制",
      "url": "https://www.zhihu.com/search?q=notability&utm_content=search_hot&type=content"
    },
    {
      "name": "马斯克",
      "query": "马斯克中文发《七步诗》",
      "url": "https://www.zhihu.com/search?q=%E9%A9%AC%E6%96%AF%E5%85%8B&utm_content=search_hot&type=content"
    },
    ...
}

主要代码

头文件

//@ 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;
};

// 定义委托,作为返回
DECLARE_DYNAMIC_MULTICAST_DELEGATE_OneParam(FRequestCompleteDelegate, const TArray<FNewsItem>&, Data); //注意此处的参数类型

UCLASS()
class RUBIKSCUBE_API UAsyncHttpObject : public UBlueprintAsyncActionBase
{
	GENERATED_BODY()
		
public:
	UAsyncHttpObject();
	// 自定义的异步蓝图节点
	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);

	//输出节点
	UPROPERTY(BlueprintAssignable)
		FRequestCompleteDelegate OnSucceeded;

	//输出节点
	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(); //防止自动GC
	}
}

UAsyncHttpObject* UAsyncHttpObject::AsyncHttpURLRequest( const FString& url) {
	UAsyncHttpObject* AsyncHttpObject = NewObject<UAsyncHttpObject>();
	AsyncHttpObject->HttpRequestStar(url);	
	return AsyncHttpObject;
}

//开始请求
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时候用
	//request->OnRequestProgress().BindUObject() 绑定进度
	request->OnProcessRequestComplete().BindUObject(this, &UAsyncHttpObject::HttpRequest_RecHandle); //请求回调
	request->ProcessRequest();
}
//请求回调
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)) // 获取数组
			{
				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); // 成功的执行
				RemoveFromRoot();
				return;
			}
		}
	}
	OnFailed.Broadcast({}); // 失败的执行
	RemoveFromRoot();
}

蓝图部分和效果#

异步下载文件

主要代码 (本文地址)

头文件

//@ 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);

// 异步下载文件
	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);

	//输出节点
	UPROPERTY(BlueprintAssignable)
		FDownloadProgressDelegate OnProgressUpdate; //最好把有参数的放在前面，不然参数在蓝图节点有时候被吃掉了

	//输出节点
	UPROPERTY(BlueprintAssignable)
		FDownloadDelegate OnSucc;

	//输出节点
	UPROPERTY(BlueprintAssignable)
		FDownloadDelegate OnFailed;

cpp

//@ https://www.cnblogs.com/shiroe/p/15500780.html
// 异步下载
UAsyncHttpObject* UAsyncHttpObject::AsyncHttpDownload(const FString& url)
{
	UAsyncHttpObject* AsyncHttpObject = NewObject<UAsyncHttpObject>();
	AsyncHttpObject->DownloadRequestStart(url);
	return AsyncHttpObject;
}

//开始请求下载
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); //请求回调
	request->OnRequestProgress().BindUObject(this, &UAsyncHttpObject::DownloadProgress);// 下载进度
	request->ProcessRequest();

	RemoveFromRoot(); // 手动GC
}

////请求回调
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;
}

// 下载进度
void UAsyncHttpObject::DownloadProgress(FHttpRequestPtr request, int32 bytesSent, int32 bytesReceived)
{
	if (request->GetResponse()->GetContentLength() > 0)
	{
		TArray<uint8> EmptyData;
		OnProgressUpdate.Broadcast(bytesReceived, request->GetResponse()->GetContentLength(),EmptyData);
	}
}

蓝图及效果

posted @ 2021-11-02 20:01 砥才人阅读(3547) 评论(0) 编辑收藏举报

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【UE4 C++】HTTP 异步请求 json 数据和下载文件

准备工作

请求 json 数据

异步下载文件

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