UE4 HTTP使用

目录

• 传输数据
• 传输使用的结构体
• 模块依赖
• 头文件
• 命令发送流程

本文记录了UE4 HTTP的使用并且以Post为案例。

GET请求 可以访问URI资源

Post传输实体

传输数据#

使用json

结构体转json

	/**
	 * Converts from a UStruct to a json string containing an object, using exportText
	 *
	 * @param StructDefinition UStruct definition that is looked over for properties
	 * @param Struct The UStruct instance to copy out of
	 * @param JsonObject Json Object to be filled in with data from the ustruct
	 * @param CheckFlags Only convert properties that match at least one of these flags. If 0 check all properties.
	 * @param SkipFlags Skip properties that match any of these flags
	 * @param Indent How many tabs to add to the json serializer
	 * @param ExportCb Optional callback for types we don't understand. This is called right before falling back to the generic ToString()
	 * @param bPrettyPrint Option to use pretty print (e.g., adds line endings) or condensed print
	 *
	 * @return False if any properties failed to write
	 */
	static bool UStructToJsonObjectString(const UStruct* StructDefinition, const void* Struct, FString& OutJsonString, int64 CheckFlags, int64 SkipFlags, int32 Indent = 0, const CustomExportCallback* ExportCb = nullptr, bool bPrettyPrint = true);

Json转结构体

	/**
	 * Converts from a UStruct to a json string containing an object, using exportText
	 *
	 * @param StructDefinition UStruct definition that is looked over for properties
	 * @param Struct The UStruct instance to copy out of
	 * @param JsonObject Json Object to be filled in with data from the ustruct
	 * @param CheckFlags Only convert properties that match at least one of these flags. If 0 check all properties.
	 * @param SkipFlags Skip properties that match any of these flags
	 * @param Indent How many tabs to add to the json serializer
	 * @param ExportCb Optional callback for types we don't understand. This is called right before falling back to the generic ToString()
	 * @param bPrettyPrint Option to use pretty print (e.g., adds line endings) or condensed print
	 *
	 * @return False if any properties failed to write
	 */
	static bool UStructToJsonObjectString(const UStruct* StructDefinition, const void* Struct, FString& OutJsonString, int64 CheckFlags, int64 SkipFlags, int32 Indent = 0, const CustomExportCallback* ExportCb = nullptr, bool bPrettyPrint = true);

传输使用的结构体#

USTRUCT()
struct FRequest_Login {
	GENERATED_BODY()
	UPROPERTY() FString email;
	UPROPERTY() FString password;

	FRequest_Login() {}
};

USTRUCT()
struct FResponse_Login {
	GENERATED_BODY()
	UPROPERTY() int id;
	UPROPERTY() FString name;
	UPROPERTY() FString hash;

	FResponse_Login() {}
};

模块依赖#

Before you start make sure you have included the required dependencies.

# Path: Source/YourProject/YourProject.Build.cs
PrivateDependencyModuleNames.AddRange(new string[] { "Http", "Json", "JsonUtilities" });

• Http is our trusty ue4 http implementation.
• Json is the json conversion library
• JsonUtilities has the FJsonObjectConverter we will be using to convert Json data to Struct data

头文件#

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

命令发送流程#

1、建立一个 TSharedRef Request对象，把需要发送的json数据转成FString

构建一个这样的对象需要使用 HTTPModule

Http = &FHttpModule::Get(); 

template <typename StructType>
void AHttpService::GetJsonStringFromStruct(StructType FilledStruct, FString& StringOutput) {
	FJsonObjectConverter::UStructToJsonObjectString(StructType::StaticStruct(), &FilledStruct, StringOutput, 0, 0);
}

2、然后设置URL，发送目标地点

TSharedRef<IHttpRequest> Request = Http->CreateRequest();
Request->SetURL(“”);

3、给IHttpRequest SetHeader(有时候也可以省略)

	Request->SetHeader(TEXT("User-Agent"), TEXT("X-UnrealEngine-Agent"));
	Request->SetHeader(TEXT("Content-Type"), TEXT("application/json"));
	Request->SetHeader(TEXT("Accepts"), TEXT("application/json"));
	Request->SetHeader(AuthorizationHeader, AuthorizationHash);

4、设置POST命令，传递json数据，以字符串发送，如果是GET命令不需要传递content

	Request->SetVerb("POST");
	Request->SetContentAsString(ContentJsonString);

5、设置HTTP执行完之后的回调

	Request->OnProcessRequestComplete().BindUObject(this, &AHttpService::LoginResponse);

绑定的回调的委托类型是一个单播三个参数的委托

DECLARE_DELEGATE_ThreeParams(FHttpRequestCompleteDelegate, FHttpRequestPtr /*Request*/, FHttpResponsePtr /*Response*/, bool /*bConnectedSuccessfully*/);

6、执行这个HTTP，可以看是否执行成功

	Request->ProcessRequest();

7、执行完了进入回调

判断是否执行成功

bool AHttpService::ResponseIsValid(FHttpResponsePtr Response, bool bWasSuccessful) {
	if (!bWasSuccessful || !Response.IsValid()) return false;
	if (EHttpResponseCodes::IsOk(Response->GetResponseCode())) return true;
	else {
		UE_LOG(LogTemp, Warning, TEXT("Http Response returned error code: %d"), Response->GetResponseCode());
		return false;
	}
}
template <typename StructType>
void AHttpService::GetStructFromJsonString(FHttpResponsePtr Response, StructType& StructOutput) {
	StructType StructData;
	FString JsonString = Response->GetContentAsString();
	FJsonObjectConverter::JsonObjectStringToUStruct<StructType>(JsonString, &StructOutput, 0, 0);
}
void AHttpService::LoginResponse(FHttpRequestPtr Request, FHttpResponsePtr Response, bool bWasSuccessful) {
	if (!ResponseIsValid(Response, bWasSuccessful)) return;

	FResponse_Login LoginResponse;
	GetStructFromJsonString<FResponse_Login>(Response, LoginResponse);

	UE_LOG(LogTemp, Warning, TEXT("Id is: %d"), LoginResponse.id);
	UE_LOG(LogTemp, Warning, TEXT("Name is: %s"), *LoginResponse.name);
}

tips:可以通过自己记录一个TMap来维护一个多播的列表让HTTP变成多播的