自己很low啊都是给自己看的 

一、简单工厂方法

简单工厂方法定义一个用于创建对象的类，该类接受一个参数，通过参数决定创建不同的对象。

    GOF并没有把简单工厂方法定义为23种设计模式之一，可以认为简单工厂方法是工厂方法的简化形式。

    为了体现简单工厂方法和工厂方法的区别和联系，此处把简单工厂方法先单独讲一下。

模拟场景

    假设你要生产电脑，电脑由硬盘、内存条、CPU、主板的部件组成。你为了保证供应链可靠，每种部件都选择了至少两家供应商。比如：

硬盘供应商 seagate、Toshiba

内存条供应商 SAMSUNG、Crucial

CPU供应商 intel、AMD

主板供应商 intel、AMD

    此处列出多个部件是为了后面讲解工厂方法、抽象工厂方法时使用同一个模拟场景。本章讲简单工厂方法暂时不需要涉及这么多部件，所以仅以硬盘这一个部件为例进行讲解。

实现的思路

    硬盘就是要创建的对象（即：产品）。为了让不同供应商提供的硬盘可以通用，要定义一个硬盘产品类，并让不同供应商的硬盘都继承硬盘产品类的接口。

    还需要定义一个创建硬盘对象的类（即：工厂）。工厂类根据参数决定创建哪家供应商的硬盘对象。

实现硬盘对象创建

    参与者:

（1）Product: HardDisk 定义硬盘对象的接口

（2）Concrete Product: SeagateHardDisk, ToshibaHardDisk 实现不同供应商的硬盘

（3）SimpleFactory: HardDiskFactory 根据参数，创建不同供应商的硬盘对象

    UML：

HardDisk代码示例：

    hard_disk.h：

#ifndef HARD_DISK_H#define HARD_DISK_H
struct HardDisk {
   
       void (*Operation)(struct HardDisk *this);};
#endif

SeagateHardDisk代码示例：

    seagate_hard_disk.h：​​​​​​​

#ifndef SEAGATE_HARD_DISK_H#define SEAGATE_HARD_DISK_H
#include "hard_disk.h"
struct SeagateHardDisk {
   
       struct HardDisk hardDisk;};
// 构造函数void SeagateHardDisk(struct SeagateHardDisk *this);
// 析构函数void _SeagateHardDisk(struct SeagateHardDisk *this);
#endif

    seagate_hard_disk.c：​​​​​​​

#include "seagate_hard_disk.h"#include "stdio.h"
void SeagateOperation(struct SeagateHardDisk *this){
   
       printf("这是 Seagate 硬盘\n");}
void SeagateHardDisk(struct SeagateHardDisk *this){
   
       this->hardDisk.Operation = (void(*)(struct HardDisk *))SeagateOperation;}
void _SeagateHardDisk(struct SeagateHardDisk *this){
   
       this->hardDisk.Operation = NULL;}

ToshibaHardDisk代码示例：

    toshiba_hard_disk.h：​​​​​​​

#ifndef TOSHIBA_HARD_DISK_H#define TOSHIBA_HARD_DISK_H
#include "hard_disk.h"
struct ToshibaHardDisk {
   
       struct HardDisk hardDisk;};
// 构造函数void ToshibaHardDisk(struct ToshibaHardDisk *this);
// 析构函数void _ToshibaHardDisk(struct ToshibaHardDisk *this);
#endif

    toshiba_hard_disk.c：​​​​​​​

#include "toshiba_hard_disk.h"#include "stdio.h"
void ToshibaOperation(struct ToshibaHardDisk *this){
   
       printf("这是 Toshiba 硬盘\n");}
void ToshibaHardDisk(struct ToshibaHardDisk *this){
   
       this->hardDisk.Operation = (void(*)(struct HardDisk *))ToshibaOperation;}
void _ToshibaHardDisk(struct ToshibaHardDisk *this){
   
       this->hardDisk.Operation = NULL;}

HardDiskFactory代码示例：

    hard_disk_factory.h：​​​​​​​

#ifndef HARD_DISK_FACTORY_H#define HARD_DISK_FACTORY_H
#include "hard_disk.h"
enum HARD_DISK_SUPPLIER_E {
   
       HARD_DISK_SUPPLIER_SEAGATE,    HARD_DISK_SUPPLIER_TOSHIBA};
struct HardDiskFactory {
   
       struct HardDisk* (*Create)(struct HardDiskFactory *this,                                enum HARD_DISK_SUPPLIER_E supplier);    void (*Destroy)(struct HardDiskFactory *this,                     struct HardDisk* hardDisk);};
// 构造函数void HardDiskFactory(struct HardDiskFactory *this);
// 析构函数void _HardDiskFactory(struct HardDiskFactory *this);
#endif

    hard_disk_factory.c：​​​​​​​

#include "hard_disk_factory.h"#include "seagate_hard_disk.h"#include "toshiba_hard_disk.h"#include "stdio.h"#include "stdlib.h"
struct HardDisk *Create(struct HardDiskFactory *this,                         enum HARD_DISK_SUPPLIER_E supplier) {
   
       switch (supplier) {
   
           case HARD_DISK_SUPPLIER_SEAGATE:        {
   
               struct SeagateHardDisk *seagateHardDisk = NULL;            if ((seagateHardDisk = malloc(sizeof(struct SeagateHardDisk))) == NULL) {
   
                   printf("fail in malloc\n");                return NULL;            }            SeagateHardDisk(seagateHardDisk);            return (struct HardDisk *)seagateHardDisk;        }        case HARD_DISK_SUPPLIER_TOSHIBA:        {
   
               struct ToshibaHardDisk *toshibaHardDisk = NULL;            if ((toshibaHardDisk = malloc(sizeof(struct ToshibaHardDisk))) == NULL) {
   
                   printf("fail in malloc\n");                return NULL;            }            ToshibaHardDisk(toshibaHardDisk);            return (struct HardDisk *)toshibaHardDisk;        }        default:            printf("未知的供应商\n");            return NULL;    }}
void Destroy(struct HardDiskFactory *this, struct HardDisk* hardDisk){
   
       if (hardDisk != NULL) {
   
           free(hardDisk);    }}
// 构造函数void HardDiskFactory(struct HardDiskFactory *this){
   
       this->Create = Create;    this->Destroy = Destroy;}
// 析构函数void _HardDiskFactory(struct HardDiskFactory *this){
   
       this->Create = NULL;    this->Destroy = NULL;}

客户端代码示例：​​​​​​​

#include "hard_disk.h"#include "hard_disk_factory.h"#include "stddef.h"
void main(){
   
       struct HardDisk *hardDisk = NULL;
    struct HardDiskFactory hardDiskFactory;    HardDiskFactory(&hardDiskFactory);        // 创建 seagate 硬盘对象    hardDisk = hardDiskFactory.Create(&hardDiskFactory, HARD_DISK_SUPPLIER_SEAGATE);    // 使用 seagate 硬盘对象    hardDisk->Operation(hardDisk);      // 销毁 seagate 硬盘对象    hardDiskFactory.Destroy(&hardDiskFactory, hardDisk);               // 创建 toshiba 硬盘对象    hardDisk = hardDiskFactory.Create(&hardDiskFactory, HARD_DISK_SUPPLIER_TOSHIBA);    // 使用 seagate 硬盘对象    hardDisk->Operation(hardDisk);    // 销毁 toshiba 硬盘对象    hardDiskFactory.Destroy(&hardDiskFactory, hardDisk);            _HardDiskFactory(&hardDiskFactory);}

客户端显示示例：​​​​​​​

./hard_disk这是 Seagate 硬盘这是 Toshiba 硬盘

whaosoft aiot http://143ai.com