▼代码开始（Cpp文件）
// Fill out your copyright notice in the Description page of Project Settings.

#include "AS01.h"

/*void UAS01::PostGameplayEffectExecute(const FGameplayEffectModCallbackData & Data)
{
    return;
}*/

▲代码结束

▼代码开始（h文件）
// Fill out your copyright notice in the Description page of Project Settings.

#pragma once

#include "CoreMinimal.h"
#include "AttributeSet.h"
#include "AS01.generated.h"

/**
 * 
 */
UCLASS()
class GATUT_API UAS01 : public UAttributeSet
{
    GENERATED_BODY()
    
    
public:
    UPROPERTY(Category = "Wizard Attributes | Health", EditAnywhere, BlueprintReadWrite)
        float Health;
    //virtual void PostGameplayEffectExecute(const struct FGameplayEffectModCallbackData &Data) override;

};
▲代码结束

▼代码开始
// Fill out your copyright notice in the Description page of Project Settings.

#pragma once

#include "CoreMinimal.h"
#include "AttributeSet.h"
#include "AS01.generated.h"

/**
 * 
 */
UCLASS()
class GATUT_API UAS01 : public UAttributeSet
{
    GENERATED_BODY()
    
    
public:
    UPROPERTY(Category = "Wizard Attributes | Health", EditAnywhere, BlueprintReadWrite)
        float Health;
    virtual void PostGameplayEffectExecute(const struct FGameplayEffectModCallbackData &Data) override;//先无视这个

    FGameplayAttribute HealthAttribute();
//获得Health属性类型（或者说获得Health键，用来标识Health）；

    virtual void PreAttributeChange(const FGameplayAttribute& Attribute, float& NewValue);
};

▲代码结束
在AS01.cpp文件中实现它。
▼代码开始
// Fill out your copyright notice in the Description page of Project Settings.

#include "AS01.h"
#include "GameplayEffectExtension.h"
#include "GameplayEffect.h"
#include "GameplayEffectTypes.h"
#include "AbilitySystemComponent.h"

//先不要管这个
void UAS01::PostGameplayEffectExecute(const FGameplayEffectModCallbackData & Data)
{
    UE_LOG(LogTemp, Warning, TEXT("%s"), *FString("This AS is ready to be changed"));

    UAbilitySystemComponent* Source = Data.EffectSpec.GetContext().GetOriginalInstigatorAbilitySystemComponent();
    if (HealthAttribute() == Data.EvaluatedData.Attribute)
    {
        AActor* DamagedActor = nullptr;
        AController* DamagedController = nullptr;
        if (Data.Target.AbilityActorInfo.IsValid() && Data.Target.AbilityActorInfo->AvatarActor.IsValid())
        {
            DamagedActor = Data.Target.AbilityActorInfo->AvatarActor.Get();
            DamagedController = Data.Target.AbilityActorInfo->PlayerController.Get();

            UE_LOG(LogTemp, Warning, TEXT("The DamagedActor Name is:%s"), *( DamagedActor->GetName() ));

        }
    }
    return;
}

//返回Health属性键
FGameplayAttribute UAS01::HealthAttribute()
{
    static UProperty* Property = FindFieldChecked<UProperty>(UAS01::StaticClass(),
        GET_MEMBER_NAME_CHECKED(UAS01, Health));
    return FGameplayAttribute(Property);
}

//修改前
void UAS01::PreAttributeChange(const FGameplayAttribute & Attribute, float & NewValue)
{
    UE_LOG(LogTemp, Warning, TEXT("%s"), *FString("PreAttributeChagne AS01"));
    
    //如果这个待修改的属性是Health属性，那么就这样Clamp
    if (Attribute == HealthAttribute())
    {
        NewValue = FMath::Clamp(NewValue, 0.f, 100.f);
        //Clamp表示截取在某个范围内，如果这个不熟悉，请看官方文档中FMath中关于它的介绍

        UE_LOG(LogTemp, Warning, TEXT("%s"), *FString("43 AS01"));
    }
    
}

▲代码结束

//这些函数在AS01.h中（即AttributeSet文件中）
//表示数值修改前执行，前文说过了
virtual void PreAttributeChange(const FGameplayAttribute& Attribute, float& NewValue);
//执行前执行
virtual bool PreGameplayEffectExecute(struct FGameplayEffectModCallbackData &Data);
//执行后执行
virtual void PostGameplayEffectExecute(const struct FGameplayEffectModCallbackData &Data) override;

▼代码开始（为了让大家清晰地参考，贴出AS01.h文件）
// Fill out your copyright notice in the Description page of Project Settings.

#pragma once

#include "CoreMinimal.h"
#include "AttributeSet.h"
#include "AS01.generated.h"

/**
 * 
 */
UCLASS()
class GATUT_API UAS01 : public UAttributeSet
{
    GENERATED_BODY()
    
    
public:
    UPROPERTY(Category = "Wizard Attributes | Health", EditAnywhere, BlueprintReadWrite)
        float Health;
    virtual void PostGameplayEffectExecute(const struct FGameplayEffectModCallbackData &Data) override;

    FGameplayAttribute HealthAttribute();

    virtual void PreAttributeChange(const FGameplayAttribute& Attribute, float& NewValue);

    virtual bool PreGameplayEffectExecute(struct FGameplayEffectModCallbackData &Data);
};

▲代码结束

▼代码开始（AS01.cpp文件）
// Fill out your copyright notice in the Description page of Project Settings.

#include "AS01.h"
#include "GameplayEffectExtension.h"
#include "GameplayEffect.h"
#include "GameplayEffectTypes.h"
#include "AbilitySystemComponent.h"
//我为什么知道要添加这些头文件？这个有点难解释

//GE执行前事件，此事件仅仅在“执行前”调用
/**原文解释：
*    Called just before modifying the value of an attribute. AttributeSet can make additional modifications here. Return true to continue, or false to throw out the modification.
*    Note this is only called during an ‘execute‘. E.g., a modification to the ‘base value‘ of an attribute. It is not called during an application of a GameplayEffect, such as a 5 ssecond +10 movement speed buff.
*/
bool UAS01::PreGameplayEffectExecute(FGameplayEffectModCallbackData & Data)
{
    UE_LOG(LogTemp, Warning, TEXT("%s"), *FString("57 AS01 PreGPEE"));



    return true;
}

//GE执行后事件
/**
*    Called just before a GameplayEffect is executed to modify the base value of an attribute. No more changes can be made.
*    Note this is only called during an ‘execute‘. E.g., a modification to the ‘base value‘ of an attribute. It is not called during an application of a GameplayEffect, such as a 5 ssecond +10 movement speed buff.
*/
void UAS01::PostGameplayEffectExecute(const FGameplayEffectModCallbackData & Data)
{
    UE_LOG(LogTemp, Warning, TEXT("%s"), *FString("This AS is ready to be changed"));

    //获得施放此次修改的源头
    UAbilitySystemComponent* Source = Data.EffectSpec.GetContext().GetOriginalInstigatorAbilitySystemComponent();
    
    //此次修改的属性是Health吗？
    if (HealthAttribute() == Data.EvaluatedData.Attribute)
    {
        AActor* TargetActor = nullptr;
        AController* TargetController = nullptr;
        if (Data.Target.AbilityActorInfo.IsValid() && Data.Target.AbilityActorInfo->AvatarActor.IsValid())
        {
            TargetActor = Data.Target.AbilityActorInfo->AvatarActor.Get();
            TargetController = Data.Target.AbilityActorInfo->PlayerController.Get();

            //这里给出了修改目标TargetActor的抓取方法
            UE_LOG(LogTemp, Warning, TEXT("The TargetActor Name is:%s"), *(TargetActor->GetName() ));
        }

        AActor* SourceActor = nullptr;
        AController* SourceController = nullptr;
        AController* SourcePlayerController = nullptr;
        if (Source && Source->AbilityActorInfo.IsValid()
            && Source->AbilityActorInfo->AvatarActor.IsValid())
        {
            SourceActor = Source->AbilityActorInfo->AvatarActor.Get();
            SourceController = Source->AbilityActorInfo->PlayerController.Get();

            //这里给出了发起修改的源头SourceActor的抓取方法
            UE_LOG(LogTemp, Warning, TEXT("The SourceActor Name is:%s"), *(SourceActor->GetName()));
        }

        //Clamp，其实Clamp不是“执行后事件”最重要的逻辑
        Health = FMath::Clamp(Health, 0.f, 100.f);

        //“执行后事件”最重要的逻辑是：如果数值太低，那么表现触发特定事情，如Health触零，那么死亡。
        if (Health <= 0.f)
        {
            UE_LOG(LogTemp, Warning, TEXT("%s"), *FString("Death Logic Here 执行死亡逻辑"));
            TargetActor->Destroy();
        }
    }
    return;
}

//返回Health属性键
FGameplayAttribute UAS01::HealthAttribute()
{
    static UProperty* Property = FindFieldChecked<UProperty>(UAS01::StaticClass(),
        GET_MEMBER_NAME_CHECKED(UAS01, Health));
    return FGameplayAttribute(Property);
}

//修改前
void UAS01::PreAttributeChange(const FGameplayAttribute & Attribute, float & NewValue)
{
    UE_LOG(LogTemp, Warning, TEXT("%s"), *FString("PreAttributeChagne AS01"));
    
    //如果这个待修改的属性是Health属性，那么就这样Clamp
    if (Attribute == HealthAttribute())
    {
        NewValue = FMath::Clamp(NewValue, 0.f, 100.f);
        //Clamp表示截取在某个范围内，如果这个不熟悉，请看官方文档中FMath中关于它的介绍

        UE_LOG(LogTemp, Warning, TEXT("%s"), *FString("43 AS01"));
    }
    
}
▲代码结束

▼代码开始
// Copyright 1998-2017 Epic Games, Inc. All Rights Reserved.

#pragma once

#include "CoreMinimal.h"
#include "GameFramework/Character.h"
#include "AttributeSet.h"

#include "AbilitySystemInterface.h"
//改动1：添加头文件

#include "GATutCharacter.generated.h"




//这个枚举类型使得FGameplayAbiliyInputBinds能够映射到技能槽中
UENUM(BlueprintType)
enum class AbilityInput : uint8
    //C++11的新特性，冒号后面写的是无符号8位整数，表示这个枚举只用无符号8位整数来表示
{
    UseAbility1 UMETA(DisplayName="Use Spell 1"), //蓝图中的展示名
    UseAbility2 UMETA(DisplayName="Use Spell 2"),
    UseAbility3 UMETA(DisplayName = "Use Spell 3"),
    UseAbility4 UMETA(DisplayName = "Use Spell 4"),
    WeaponAbility UMETA(DisplayName="Use Weapon")

    //注意：被动技能也可以声明在这里，但是无须和输入做绑定。

};//*/











UCLASS(config=Game)
class AGATutCharacter : 
    public ACharacter
    ,public IAbilitySystemInterface
    //改动2：继承此接口
{
    GENERATED_BODY()

    /** Camera boom positioning the camera behind the character */
    UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = Camera, meta = (AllowPrivateAccess = "true"))
    class USpringArmComponent* CameraBoom;

    /** Follow camera */
    UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = Camera, meta = (AllowPrivateAccess = "true"))
    class UCameraComponent* FollowCamera;

    //改动3：添加一个Abi组件
    //BlueprintReadOnly的内容其实是不允许写在private区中的，如果写在private区且要蓝图可读，那么需要写上meta=(AllowPrivateAccess="true")
    UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = Abilities, meta = (AllowPrivateAccess = "true"))
        class UAbilitySystemComponent* AbilitySystem;


public:
    AGATutCharacter();

    /** Base turn rate, in deg/sec. Other scaling may affect final turn rate. */
    UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category=Camera)
    float BaseTurnRate;

    /** Base look up/down rate, in deg/sec. Other scaling may affect final rate. */
    UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category=Camera)
    float BaseLookUpRate;

protected:

    /** Resets HMD orientation in VR. */
    void OnResetVR();

    /** Called for forwards/backward input */
    void MoveForward(float Value);

    /** Called for side to side input */
    void MoveRight(float Value);

    /** 
     * Called via input to turn at a given rate. 
     * @param Rate    This is a normalized rate, i.e. 1.0 means 100% of desired turn rate
     */
    void TurnAtRate(float Rate);

    /**
     * Called via input to turn look up/down at a given rate. 
     * @param Rate    This is a normalized rate, i.e. 1.0 means 100% of desired turn rate
     */
    void LookUpAtRate(float Rate);

    /** Handler for when a touch input begins. */
    void TouchStarted(ETouchIndex::Type FingerIndex, FVector Location);

    /** Handler for when a touch input stops. */
    void TouchStopped(ETouchIndex::Type FingerIndex, FVector Location);

protected:
    // APawn interface
    virtual void SetupPlayerInputComponent(class UInputComponent* PlayerInputComponent) override;
    // End of APawn interface

public:
    /** Returns CameraBoom subobject **/
    FORCEINLINE class USpringArmComponent* GetCameraBoom() const { return CameraBoom; }
    /** Returns FollowCamera subobject **/
    FORCEINLINE class UCameraComponent* GetFollowCamera() const { return FollowCamera; }

    //改动4：添加一个返回此组件的方法
    UFUNCTION(BlueprintCallable, Category = AS)
    UAbilitySystemComponent* GetAbilitySystemComponent()const;

    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = Abilities)
        TArray< TSubclassOf<class UGameplayAbility> > MyAbilities;

    //符文
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = Abilities)
        TSubclassOf<class UGameplayAbility> Rune;
    UFUNCTION(BlueprintCallable, Category = Abilities)
        void BindTargetToAbility(AGATutCharacter* Target, TSubclassOf<UGameplayAbility> &Ability);
    virtual void BeginPlay()override;

    static FName AbilitySystemName;

    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "AttributeSets")
        TArray<TSubclassOf<class UAttributeSet>>AttributeSets;

    //Mark+
    UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = Abilities)
        UDataTable * AttrDataTable;

};


▲代码结束

▼代码开始
// Copyright 1998-2017 Epic Games, Inc. All Rights Reserved.

#include "GATutCharacter.h"
#include "AbilitySystemComponent.h"
#include "AbilitySystemGlobals.h"
#include "GameplayAbilitiesModule.h"

#include "Kismet/HeadMountedDisplayFunctionLibrary.h"
#include "Camera/CameraComponent.h"
#include "Components/CapsuleComponent.h"
#include "Components/InputComponent.h"
#include "GameFramework/CharacterMovementComponent.h"
#include "GameFramework/Controller.h"
#include "GameFramework/SpringArmComponent.h"


FName AGATutCharacter::AbilitySystemName(TEXT("AbilitySystem"));

//////////////////////////////////////////////////////////////////////////
// AGATutCharacter

AGATutCharacter::AGATutCharacter()
{
    // Set size for collision capsule
    GetCapsuleComponent()->InitCapsuleSize(42.f, 96.0f);

    // set our turn rates for input
    BaseTurnRate = 45.f;
    BaseLookUpRate = 45.f;

    // Don‘t rotate when the controller rotates. Let that just affect the camera.
    bUseControllerRotationPitch = false;
    bUseControllerRotationYaw = false;
    bUseControllerRotationRoll = false;

    // Configure character movement
    GetCharacterMovement()->bOrientRotationToMovement = true; // Character moves in the direction of input...    
    GetCharacterMovement()->RotationRate = FRotator(0.0f, 540.0f, 0.0f); // ...at this rotation rate
    GetCharacterMovement()->JumpZVelocity = 600.f;
    GetCharacterMovement()->AirControl = 0.2f;

    // Create a camera boom (pulls in towards the player if there is a collision)
    CameraBoom = CreateDefaultSubobject<USpringArmComponent>(TEXT("CameraBoom"));
    CameraBoom->SetupAttachment(RootComponent);
    CameraBoom->TargetArmLength = 300.0f; // The camera follows at this distance behind the character    
    CameraBoom->bUsePawnControlRotation = true; // Rotate the arm based on the controller

    // Create a follow camera
    FollowCamera = CreateDefaultSubobject<UCameraComponent>(TEXT("FollowCamera"));
    FollowCamera->SetupAttachment(CameraBoom, USpringArmComponent::SocketName); // Attach the camera to the end of the boom and let the boom adjust to match the controller orientation
    FollowCamera->bUsePawnControlRotation = false; // Camera does not rotate relative to arm


    AbilitySystem = CreateDefaultSubobject<UAbilitySystemComponent>(TEXT("AbilitySystem"));


    // Note: The skeletal mesh and anim blueprint references on the Mesh component (inherited from Character) 
    // are set in the derived blueprint asset named MyCharacter (to avoid direct content references in C++)
}

//////////////////////////////////////////////////////////////////////////
// Input

void AGATutCharacter::SetupPlayerInputComponent(class UInputComponent* PlayerInputComponent)
{
    // Set up gameplay key bindings
    check(PlayerInputComponent);
    PlayerInputComponent->BindAction("Jump", IE_Pressed, this, &ACharacter::Jump);
    PlayerInputComponent->BindAction("Jump", IE_Released, this, &ACharacter::StopJumping);

    PlayerInputComponent->BindAxis("MoveForward", this, &AGATutCharacter::MoveForward);
    PlayerInputComponent->BindAxis("MoveRight", this, &AGATutCharacter::MoveRight);

    // We have 2 versions of the rotation bindings to handle different kinds of devices differently
    // "turn" handles devices that provide an absolute delta, such as a mouse.
    // "turnrate" is for devices that we choose to treat as a rate of change, such as an analog joystick
    PlayerInputComponent->BindAxis("Turn", this, &APawn::AddControllerYawInput);
    PlayerInputComponent->BindAxis("TurnRate", this, &AGATutCharacter::TurnAtRate);
    PlayerInputComponent->BindAxis("LookUp", this, &APawn::AddControllerPitchInput);
    PlayerInputComponent->BindAxis("LookUpRate", this, &AGATutCharacter::LookUpAtRate);

    // handle touch devices
    PlayerInputComponent->BindTouch(IE_Pressed, this, &AGATutCharacter::TouchStarted);
    PlayerInputComponent->BindTouch(IE_Released, this, &AGATutCharacter::TouchStopped);

    // VR headset functionality
    PlayerInputComponent->BindAction("ResetVR", IE_Pressed, this, &AGATutCharacter::OnResetVR);

    //测试证明：在本篇的教程里，不加这一句也可以
    //AbilitySystem->BindAbilityActivationToInputComponent(PlayerInputComponent, FGameplayAbiliyInputBinds("ConfirmInput", "CancelInput", "AbilityInput"));
}

UAbilitySystemComponent * AGATutCharacter::GetAbilitySystemComponent() const
{
    return AbilitySystem;
}



void AGATutCharacter::BindTargetToAbility(AGATutCharacter * Target, TSubclassOf<UGameplayAbility>& Ability)
{
    if (Ability == nullptr || Target == nullptr)return;

    AbilitySystem->InitAbilityActorInfo(this, Target);
    AbilitySystem->GiveAbility(FGameplayAbilitySpec(Rune.GetDefaultObject(), 1, 0));
    UE_LOG(LogTemp, Warning, TEXT("%s"), *FString("BindTargetToAbility"));
}

void AGATutCharacter::BeginPlay()
{
    Super::BeginPlay();
    
    if (AbilitySystem == nullptr)return;

    UE_LOG(LogTemp, Warning, TEXT("%s"), *FString("Char Beginplay 97"));
    if (HasAuthority() && MyAbilities.Num()) {
        UE_LOG(LogTemp, Warning, TEXT("%s"), *FString("Char Bplay 99"));
        for (auto i = 0; i<MyAbilities.Num(); i++)
        {
            if (MyAbilities[i] == nullptr)continue;
            AbilitySystem->GiveAbility(FGameplayAbilitySpec(MyAbilities[i].GetDefaultObject(), 1, 0));
            UE_LOG(LogTemp, Warning, TEXT("%s"), *FString("103bp we register an ability!"));
        }
        UE_LOG(LogTemp, Warning, TEXT("%s"), *FString("All Ablities registered"));
    }
    AbilitySystem->InitAbilityActorInfo(this, this);
    //这两个参数以为着Owner和Avatar
    UE_LOG(LogTemp, Warning, TEXT("%s"), *FString("Char Bplay 105"));//*/

    for (TSubclassOf<UAttributeSet>& Set : AttributeSets)
    {
        AbilitySystem->InitStats(Set, AttrDataTable);//Mark+

    }

    //UAbilitySystemGlobals* ASG = IGameplayAbilitiesModule::Get().GetAbilitySystemGlobals();
    //FAttributeSetInitter* ASI = ASG->GetAttributeSetInitter();
}




void AGATutCharacter::OnResetVR()
{
    UHeadMountedDisplayFunctionLibrary::ResetOrientationAndPosition();
}

void AGATutCharacter::TouchStarted(ETouchIndex::Type FingerIndex, FVector Location)
{
        Jump();
}

void AGATutCharacter::TouchStopped(ETouchIndex::Type FingerIndex, FVector Location)
{
        StopJumping();
}

void AGATutCharacter::TurnAtRate(float Rate)
{
    // calculate delta for this frame from the rate information
    AddControllerYawInput(Rate * BaseTurnRate * GetWorld()->GetDeltaSeconds());
}

void AGATutCharacter::LookUpAtRate(float Rate)
{
    // calculate delta for this frame from the rate information
    AddControllerPitchInput(Rate * BaseLookUpRate * GetWorld()->GetDeltaSeconds());
}

void AGATutCharacter::MoveForward(float Value)
{
    if ((Controller != NULL) && (Value != 0.0f))
    {
        // find out which way is forward
        const FRotator Rotation = Controller->GetControlRotation();
        const FRotator YawRotation(0, Rotation.Yaw, 0);

        // get forward vector
        const FVector Direction = FRotationMatrix(YawRotation).GetUnitAxis(EAxis::X);
        AddMovementInput(Direction, Value);
    }
}

void AGATutCharacter::MoveRight(float Value)
{
    if ( (Controller != NULL) && (Value != 0.0f) )
    {
        // find out which way is right
        const FRotator Rotation = Controller->GetControlRotation();
        const FRotator YawRotation(0, Rotation.Yaw, 0);
    
        // get right vector 
        const FVector Direction = FRotationMatrix(YawRotation).GetUnitAxis(EAxis::Y);
        // add movement in that direction
        AddMovementInput(Direction, Value);
    }
}

▲代码结束