[UE4]C++实现动态加载的问题：LoadClass<t>()和LoadObject<t>()
发表于2018-02-26
动态加载UObject和动态加载UClass分别用LoadObject<T>()，和LoadClass<T>() ，两者均在在UObjectGlobals.h中。
区别：
LoadObject<T>()用来加载非蓝图资源，比如动画、贴图、音效等资源；
LoadClass<T>()用来加载蓝图并获取蓝图Class，比如角色蓝图。如果要用蓝图创建对象，必须先通过LoadClass获取class，然后再通过SpawnActor生成对象。
LoadClass参数注意事项：
另外注意：LoadClass<T>的模版名称，不能直接写UBlueprint，例如：LoadClass<UBlueprint>是错误的，创建蓝图时选择的是什么父类，则写对应的父类名，假如是Actor，那么要写成：LoadClass<AActor>，否则无法加载成功。
路径名也必须带_C后缀（LoadObject不需要带_C后缀），例如，蓝图路径是：Blueprint'/Game/Blueprints/MyBP.MyBP'，
加后缀以后，则是：Blueprint'/Game/Blueprints/MyBP.MyBP_C'，
例子：
UClass* Test = LoadClass<AActor>(NULL, TEXT("Blueprint'/Game/Blueprints/MapPathBrush_BP.MapPathBrush_BP_C'"));
官方还没出文档，只能先看代码注释：
// Load an object.
template< class T >
inline T* LoadObject( UObject* Outer, const TCHAR* Name, const TCHAR* Filename=nullptr, uint32 LoadFlags=LOAD_None, UPackageMap* Sandbox=nullptr )
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return (T*)StaticLoadObject( T::StaticClass(), Outer, Name, Filename, LoadFlags, Sandbox );
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// Load a class object.
template< class T >
inline UClass* LoadClass( UObject* Outer, const TCHAR* Name, const TCHAR* Filename=nullptr, uint32 LoadFlags=LOAD_None, UPackageMap* Sandbox=nullptr )
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return StaticLoadClass( T::StaticClass(), Outer, Name, Filename, LoadFlags, Sandbox );
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/** * Find or load an object by string name with optional outer and filename specifications. * These are optional because the InName can contain all of the necessary information. * * @param ObjectClass The class (or a superclass) of the object to be loaded. * @param InOuter An optional object to narrow where to find/load the object from * @param InName String name of the object. If it's not fully qualified, InOuter and/or Filename will be needed * @param Filename An optional file to load from (or find in the file's package object) * @param LoadFlags Flags controlling how to handle loading from disk * @param Sandbox A list of packages to restrict the search for the object * @param bAllowObjectReconciliation Whether to allow the object to be found via FindObject in the case of seek free loading * * @return The object that was loaded or found. NULL for a failure. */ COREUOBJECT_API UObject* StaticLoadObject( UClass* Class, UObject* InOuter, const TCHAR* Name, const TCHAR* Filename = NULL, uint32 LoadFlags = LOAD_None, UPackageMap* Sandbox = NULL, bool bAllowObjectReconciliation = true ); COREUOBJECT_API UClass* StaticLoadClass(UClass* BaseClass, UObject* InOuter, const TCHAR* Name, const TCHAR* Filename = NULL, uint32 LoadFlags = LOAD_None, UPackageMap* Sandbox = NULL);
LoadObject参数注意事项：
LoadObject加载例子，不需要添加后缀：
UTexture2D* Tex = LoadObject<UTexture2D>(NULL, TEXT("Texture2D'/Game/Textures/UI/tex_test001.tex_test001'"));
可以用LoadObject加载的文件包括：
Texture、Material、SoundWave、SoundCue、ParticlesSystem、AnimMontage、BlendSpace(1D，2D，3D)、AnimSequence、AnimBlueprint、SkeletalMesh等等。这些文件的父类都是UObject，所以也可以先加载为UObject*然后再强转为具体的类型，例如：
UObject* Obj = LoadObject<UObject>(NULL, TEXT("SkeletalMesh'/Game/MyMesh.MyMesh'"));
USkeletalMesh* MyMesh = Cast<USkeletalMesh*>(Obj);
另外有两个全局函数叫：StaticLoadObject()和StaticLoadClass()，应该是LoadObject<T>()和LoadClass<T>()的早期版本，前者需要手动强转，后者使用模版封装过，使用更方便，推荐使用后者
来自：http://aigo.iteye.com/blog/2281558