C#和.Net框架

本章简介

• JSON格式
• 解析JSON文件
• 修改JSON文件

JSON格式

• 十分钟搞定JSON和JSON对象

想要使用JSO相关工具，必须在ProjectName.Build.cs，在其中添加

PublicDependencyModuleNames.AddRange
(
    new string[] 
    {
         "Core", 
         "CoreUObject", 
         "Engine", 
         "InputCore",
         "Slate",
         "SlateCore",
         "Json",
         "JsonUtilities"
    }
);

解析JSON文件

• 我们在 \Content\Res\Data.json中天下如下测试例子

/** Data.json **/
[
    {
        "1-1":"1-1",
        "1-2":"1-2"
    },
    {
        "2-1":"2-1"
    },
    {
        "3-1":
        [
            {
                "1":"3-1-1"
            },
            {
                "2":"3-1-2"
            }
        ]
    }
]

• 我们要首先得将他以字符串的形式读入

  FPaths::GameContentDir() 能获取 */Content/ 的位置
  FFileHelper::LoadFileToString() Load a text file to an FString.

bool MyJsonHandle::LoadStringFromFile(FString & RelativePathName, FString & FileName, FString & ResultString)
{
    if (!FileName.IsEmpty())
    {
        FString AbsloutePathName = FPaths::GameContentDir() + RelativePathName + FileName;
        if (FPaths::FileExists(AbsloutePathName))
        {
            if (FFileHelper::LoadFileToString(ResultString, *AbsloutePathName))
            {
                return true;
            }
        }
    }
    return false;
}
`

• 接下来我们来解析我们所获取到的FString

/** MyJsonHandle.cpp **/
bool MyJsonHandle::RecordDataJsonRead()
{
    FString result;
    //这是我们上面自定义的函数
    LoadStringFromFile(RelativePathName, DataFileName, result);

    TArray<TSharedPtr<FJsonValue>> JsonParse;
    TSharedRef<TJsonReader<TCHAR>> JsonReader = TJsonReaderFactory<TCHAR>::Create(result);

    if (FJsonSerializer::Deserialize(JsonReader, JsonParse))
    { //这样解析后的节点全部存在JsonParse中
        UE_LOG(LogTemp, Warning, TEXT("%s"), *JsonParse[0]->AsObject()->GetStringField(FString("1-1")));
        UE_LOG(LogTemp, Warning, TEXT("%s"), *JsonParse[0]->AsObject()->GetStringField(FString("1-2")));
        UE_LOG(LogTemp, Warning, TEXT("%s"), *JsonParse[1]->AsObject()->GetStringField(FString("2-1")));
        //如果对象是嵌套的，则需要再声明一次TArray<TSharedPtr<FJsonValue>>来获取
        TArray<TSharedPtr<FJsonValue>> JsonParse3 = JsonParse[2]->AsObject()->GetArrayField(FString("3-1"));
        if (JsonParse3.IsValidIndex(0))
        {
            for (int cnt = 1; cnt <= JsonParse3.Num(); ++cnt)
            {
                UE_LOG(LogTemp, Warning, TEXT("%s"), *JsonParse3[cnt-1]->AsObject()->GetStringField(FString::FromInt(cnt)));
            }
        }
        else
        {
            UE_LOG(LogTemp, Warning, TEXT("error JsonParse3"));
        }

        return true;
    }

    return false;
}

修改JSON文件

设置单个属性

• 通过下面的代码生成一个

  /**
  * A Json Object is a structure holding an unordered set of name/value pairs.
  * In a Json file, it is represented by everything between curly braces {}.
  */
  TSharedPtr<FJsonObject> Object1 = MakeShareable(new FJsonObject);
  Object1->SetStringField("1-1", "1--1");
  Object1->SetStringField("1-2", "1--2");
  TSharedPtr<FJsonValueObject> CultureValue = MakeShareable(new FJsonValueObject(CultureObject));