ue4-接口的使用及对象回收机制

分类于

自己现在在做的demo中，用到了大量的UObject对象，战斗的过程中会频繁的new出这些对象，无疑会消耗很大的cpu，为了减少和现有架构的耦合性，本想用继承的方式写个基类，发现ue中不能同时继承两个UObject。根据answerhub里的提示，就是用接口来做。

接口的弊端是里面的成员不能用UPROPERTY宏标记给蓝图识别，不过可以在子类中写个方法来“曲线救国”

这个回收机制的相关类

img

1、ObjInter这个是给要回收对象继承的接口

ObjInter.h

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
#include "ObjInter.generated.h"

class UObjMgr;

UINTERFACE()
class UObjInterface : public UInterface
{
    GENERATED_UINTERFACE_BODY()
};

class IObjInterface
{
    GENERATED_IINTERFACE_BODY()
public:
    IObjInterface();

    virtual void Reset() = 0;   //抽象接口，要求子类必须重写
    virtual void SetObj(UObject* _obj); 
    virtual void Recycle();

private:
    UObjMgr*    mObjMgr;    //回收中心，类似cocos里Node里的一系列mgr
    UObject*    mOwnObj;    //宿主对象
};

ObjInter.cpp

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
#include "MySlate.h"
#include "ObjInter.h"

#include "./ObjMgr.h"

UObjInterface::UObjInterface(const class FObjectInitializer& ObjectInitializer)
    : Super(ObjectInitializer)
{
    UE_LOG(ObjLogger, Warning, TEXT("--- UObjInterface::UObjInterface 111111"));
}


IObjInterface::IObjInterface() 
 : mOwnObj(nullptr)
{
    UE_LOG(ObjLogger, Warning, TEXT("--- IObjInterface::IObjInterface"));
}

void IObjInterface::SetObj(UObject* _obj)
{
    UE_LOG(ObjLogger, Warning, TEXT("--- IObjInterface::SetObj, construct - %s"), *_obj->GetClass()->GetName());
    mObjMgr = UObjMgr::GetInstance();
    mOwnObj = _obj;
    Reset();
}
void IObjInterface::Recycle()
{
    UE_LOG(ObjLogger, Warning, TEXT("--- IObjInterface::Recycle - %s"), *mOwnObj->GetClass()->GetName());
    Reset();
    mObjMgr->Recycle(mOwnObj);
}

2、ObjMgr是回收中心，里面有个回收池

回收池以类名为key，ue中的反射机制可以获取UObject具体的类名，value为对象数组
ObjMgr.h

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
UCLASS()
class UObjMgr : public UObject, public USingleton<UObjMgr>
{
    GENERATED_BODY()

public:
    UObjMgr();
    virtual ~UObjMgr();
    virtual void BeginDestroy() override;

public:
    template<typename TRetType>
    TRetType*       GetObj(UClass* _cls); //根据模板获取对象

    void            Recycle(UObject* _obj);
    auto&           GetObjMap() { return mObjMap; }

public:
    //蓝图对象类设置
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "UObjMgr")
        TSubclassOf<AMyChar>        mCharCls; 
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "UObjMgr")
        TSubclassOf<AMyBullet>      mBulletCls;

    //--------- pk Begin -----
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "UObjMgr")
        TSubclassOf<UFightData>     mFightDataCls;
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "UObjMgr")
        TSubclassOf<UPkProcess>     mPkProcessCls; 
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "UObjMgr")
        TSubclassOf<UPkMsg>         mPkMsgCls; 
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "UObjMgr")
        TSubclassOf<UParam>         mPkParamCls;
    //--------- pk End -----

    //--------- filter Begin -----
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "UObjMgr")
        TSubclassOf<UCircleFilter>  mCircleFltCls;
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "UObjMgr")
        TSubclassOf<ULockFilter>    mLockFltCls;
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "UObjMgr")
        TSubclassOf<URectFilter>    mRectFltCls;
    //--------- filter End -----


    //--------- skill Begin -----
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "UObjMgr")
        TSubclassOf<UCoolDown>  mCoolDownCls;
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "UObjMgr")
        TSubclassOf<USkillFunction> mSkillFuncCls;
    //--------- skill End -----

    //--------- buff Begin -----
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "UObjMgr")
        TSubclassOf<UAppendBuff>    mAppBuffCls;
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "UObjMgr")
        TSubclassOf<UCommonBuff>    mComBuffCls;
    //--------- buff End -----

    //--------- function Begin -----
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "UObjMgr")
        TSubclassOf<UAddBuff>       mAddBuffCls;
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "UObjMgr")
        TSubclassOf<UAttack>        mAttackCls;
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "UObjMgr")
        TSubclassOf<UAttackPhy>     mAttackPhyCls;
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "UObjMgr")
        TSubclassOf<USuckup>        mSuckupCls;
    //--------- function End -----

private:
    TMap<FString, TArray<UObject*>>     mObjMap; //对象回收池
};

#define GetObjMgr()         UObjMgr::GetInstance()

（ps:一系列的TSubclassOf是为了实现蓝图对象，如果某些类派生了某些蓝图类，在初始化时指定该蓝图类，即可new出蓝图实例对象）

ObjMgr.cpp

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
UObjMgr::UObjMgr() : Super()
{
    //default cpp class
    mFightDataCls       = UFightData::StaticClass();
    mPkProcessCls       = UPkProcess::StaticClass();
    mPkMsgCls           = UPkMsg::StaticClass();
    mPkParamCls         = UParam::StaticClass();

    mCircleFltCls       = UCircleFilter::StaticClass();
    mLockFltCls         = ULockFilter::StaticClass();
    mRectFltCls         = URectFilter::StaticClass();

    mCoolDownCls        = UCoolDown::StaticClass();
    mSkillFuncCls       = USkillFunction::StaticClass();

    mAppBuffCls         = UAppendBuff::StaticClass();
    mComBuffCls         = UCommonBuff::StaticClass();

    mAddBuffCls         = UAddBuff::StaticClass();
    mAttackCls          = UAttack::StaticClass();
    mAttackPhyCls       = UAttackPhy::StaticClass();
    mSuckupCls          = USuckup::StaticClass();
}

UObjMgr::~UObjMgr()
{
    UE_LOG(ObjLogger, Warning, TEXT("--- UObjMgr::~UObjMgr"));
}

void UObjMgr::BeginDestroy()
{
    for (auto Iter = mObjMap.CreateConstIterator(); Iter; ++Iter)
    {
        for (UObject* obj : Iter->Value)
        {
            obj->RemoveFromRoot();
            obj->ConditionalBeginDestroy();
        }
    }
    mObjMap.Empty();

    UE_LOG(ObjLogger, Warning, TEXT("--- UObjMgr::BeginDestroy"));
    Super::BeginDestroy();
}

//获取回收池中的对象，不够了则new出来
template<typename TRetType>
TRetType* UObjMgr::GetObj(UClass* _cls)
{
    TArray<UObject*>* findObjVec = mObjMap.Find(_cls->GetName());
    if (findObjVec != nullptr)
    {
        if (findObjVec->Num() > 0)
        {
            UObject* obj = findObjVec->Pop();
            return Cast<TRetType>(obj);
        }
    }

    TRetType* ret = NewObject<TRetType>(TRetType::StaticClass());
    UObject* obj = (UObject*)ret;
    obj->AddToRoot();
    return ret;
}

//对象回收逻辑
void UObjMgr::Recycle(UObject* _obj)
{
    FString clsName = _obj->GetClass()->GetName();
    TArray<UObject*>* objVec = mObjMap.Find(clsName);
    if (objVec != nullptr)
    {
        objVec->Push(_obj);
    }
    else
    {
        TArray<UObject*> tmp;
        tmp.Add(_obj);
        mObjMap.Add(clsName, tmp);
    }
}

（ps：在这基础上可以继续扩展，使用一些算法定时清除对象，LRU神马的）

3、继承接口，使用回收

FightData.h

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
#include "FightData.generated.h"

UCLASS()
class UFightData : public UObject, public IObjInterface
{
    GENERATED_BODY()

public:
    UFightData();
    virtual ~UFightData();
    virtual void BeginDestroy() override;
    virtual void Reset() override;
    virtual void Recycle() override;

    UFightData* Clone();
    void Copy(UFightData* _fightData);


    float GetAttackPhy() const { return mAttackPhy; }
    float GetLv() const { return mLv; }

public:
    //原始属性
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "UCharData")
        float       mAttackPhy;     //物理攻击

public:
    //成长相关
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "UCharData")
        int         mLv;            //等级

public:
};

FightData.cpp

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
#include "../../Object/ObjMgr.h"

UFightData::UFightData() : Super(), IObjInterface()
{
    IObjInterface::SetObj(this); //设置宿主为自身
}

UFightData::~UFightData()
{
    UE_LOG(SkillLogger, Warning, TEXT("--- UFightData::~UFightData"));
}

void UFightData::BeginDestroy()
{
    UE_LOG(SkillLogger, Warning, TEXT("--- UFightData::BeginDestroy"));
    Super::BeginDestroy();
}

void UFightData::Reset()
{
    mAttackPhy = 0.f;
    mLv = 1;
}

void UFightData::Recycle()
{
    IObjInterface::Recycle();
}

UFightData* UFightData::Clone()
{   //从回收池中拿对象
    UFightData* data = GetObjMgr()->GetObj<UFightData>(GetObjMgr()->mFightDataCls);
    data->Copy(this);
    return data;
}

void UFightData::Copy(UFightData* _fightData)
{
    this->mAttackPhy = _fightData->mAttackPhy;
    this->mLv = _fightData->mLv;
}

用接口实现Broadcast，适用于多个类继承统一接口，处理不同实例对象

1
2
3
4
5
6
7
class IBehavInterface
{
    GENERATED_IINTERFACE_BODY()
public:
    UFUNCTION(BlueprintNativeEvent)
        void OnInputTap(const FVector& _pos);
};

必须用 UFUNCTION宏 声明为 BlueprintNativeEvent，所有继承这个接口的类都必须实现OnInputTap()方法

.h

1
2
3
4
5
6
7
class AMyChar : public ACharacter, public IBehavInterface
{
    GENERATED_BODY()
public:
    //重写接口方法，注意_Implementation
    virtual void OnInputTap_Implementation(const FVector& _pos) override;
};

.cpp

1
2
3
4
void AMyChar::OnInputTap_Implementation(const FVector& _pos)
{
    UE_LOG(SkillLogger, Warning, TEXT("--- AMyChar::OnInputTap_Implementation, targetId:%d, pos:%f,%f,%f"), GetUuid(), _pos.X, _pos.Y, _pos.Z);
}

调用接口

1
2
3
4
5
6
7
AMyChar* tarChar = Cast<AMyChar>(HitActor);
//调用前一定要检查一下该类是否实现了这个接口
if ( tarChar && tarChar->GetClass()->ImplementsInterface(UBehavInterface::StaticClass()) )
{
    //第一个参数目的对象，第二个参数才是接口方法的参数
    IBehavInterface::Execute_OnInputTap(tarChar, WorldPosition);
}

(ps: 一定要先检查是否实现了接口)

结果：

img

小坑

1、不能直接调 BlueprintNativeEvent 声明的方法

1
2
UFUNCTION(BlueprintNativeEvent)
void OnInputTap(const FVector& _pos);

如：

xxx->OnInputTap(xx);

这种方法必须用这种方式调用

IBehavInterface::Execute_OnInputTap(tarChar, WorldPosition);

接口中的方法暴露给蓝图使用

必须声明为为 CannotImplementInterfaceInBlueprint，且不能用 BlueprintNativeEvent 声明的方法，

被声明为 BlueprintCallable 的方法必须是 virtual 方法

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
UINTERFACE(meta = (CannotImplementInterfaceInBlueprint))
class UBTNodeInterface : public UInterface
{
    GENERATED_UINTERFACE_BODY()
};

class IBTNodeInterface 
{
    GENERATED_IINTERFACE_BODY()
public:
    IBTNodeInterface();

    UFUNCTION(BlueprintCallable, Category = "IBTNodeInterface")
        virtual int32 GetCharUUid();
};

a