利用函数指针实现C的回调函数，实现调用者和底层驱动的解耦
- 新建空项目，命名为RF_Drive,这个作为底层的驱动。
- 添加MyDrive.c文件，向文件中添加代码，模拟驱动一些函数，代码如下：
思路：
EncData和DecData实现信息的加密和解密，由于不同厂家的设备，加密和解密的方式不同，所以不能在底层驱动中实现，需要不同的厂家在自己的函数库中实现。厂家和驱动约定好相同的接口，将函数通过指针传进来，实现函数的回调。
#define _CRT_SECURE_NO_WARNINGS
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
//完成发送报文的时候,进行数据加密
//定义函数指针类型 通过函数指针类型 来约定 厂商 去实现 加密解密函数的原型
typedef int(*EncData)(unsigned char *in, int inlen, unsigned char *out, int *outlen);
typedef int(*DecData)(unsigned char *in, int inlen, unsigned char *out, int *outlen);
typedef struct _Sck_Handle
{
char version[16];
char ip[16];
int port;
unsigned char *p;
int len;
char *p2;
}Sck_Handle;
int socketclient_sendAndEnc1(void *handle, unsigned char *buf, int buflen, EncData encDataCallback)
{
int ret = 0;
unsigned char cryptbuf[4096];
int cryptbuflen = 4096;
Sck_Handle *tmpHandle = NULL;
if (handle == NULL || buf == NULL || encDataCallback == NULL)
{
ret = -1;
printf("func socketclient_sendAndEnc1() err :%d check handle == NULL err \n", ret);
return ret;
}
ret = encDataCallback(buf, buflen, cryptbuf, &cryptbuflen); //间接的调用子任务
if (ret != 0)
{
ret = -2;
printf("func socketclient_sendAndEnc1() err :%d check handle == NULL err \n", ret);
return ret;
}
tmpHandle = (Sck_Handle *)handle;
tmpHandle->len = cryptbuflen;
tmpHandle->p = (unsigned char *)malloc(cryptbuflen);
if (tmpHandle->p == NULL)
{
ret = -3;
printf("func socketclient_sendAndEnc1() err :%d mallocerr \n", ret);
return ret;
}
//把加密的明文 缓存到 内存中
memcpy(tmpHandle->p, cryptbuf, cryptbuflen);
return 0;
}
//socket客户端环境初始化
int socketclient_init(void **handle)
{
int ret = 0;
Sck_Handle *tmpHandle = NULL;
if (handle == NULL)
{
ret = -1;
printf("func socketclient_init() err :%d check handle == NULL err \n", ret);
return ret;
}
tmpHandle = (Sck_Handle *)malloc(sizeof(Sck_Handle));
if (tmpHandle == NULL)
{
ret = -2;
printf("func socketclient_init() err :%d malloc err \n", ret);
return ret;
}
memset(tmpHandle, 0, sizeof(Sck_Handle));
strcpy(tmpHandle->version, "1.0.0.1");
strcpy(tmpHandle->ip, "192.168.12.12");
tmpHandle->port = 8081;
//间接赋值
*handle = tmpHandle;
return ret;
}
//socket报文发送
int socketclient_send(void *handle, unsigned char *buf, int buflen)
{
int ret = 0;
Sck_Handle *tmpHandle = NULL;
if (handle == NULL || buf == NULL || buflen <= 0)
{
ret = -2;
printf("func socketclient_send() err :%d (handle == NULL || buf==NULL || buflen <=0 ) \n", ret);
return ret;
}
tmpHandle = (Sck_Handle *)handle;
tmpHandle->len = buflen;
tmpHandle->p = (unsigned char *)malloc(buflen);
if (tmpHandle->p == NULL)
{
ret = -2;
printf("func socketclient_send() err :%d malloc len:%d \n", ret, buflen);
return ret;
}
memcpy(tmpHandle->p, buf, buflen); //数据的缓存到内存
return ret;
}
//socket报文接受
int socketclient_recv(void *handle, unsigned char *buf, int *buflen)
{
int ret = 0;
Sck_Handle *tmpHandle = NULL;
if (handle == NULL || buf == NULL || buflen == NULL)
{
ret = -2;
printf("func socketclient_recv() err :%d (handle == NULL || buf==NULL || buflen==NULL ) \n", ret);
return ret;
}
tmpHandle = (Sck_Handle *)handle;
memcpy(buf, tmpHandle->p, tmpHandle->len);
*buflen = tmpHandle->len; //间接赋值 告诉调用者 收到的数据的长度
return ret;
}
//socket环境释放
int socketclient_destory(void *handle)
{
int ret = 0;
Sck_Handle *tmpHandle = NULL;
if (handle == NULL)
{
return -1;
}
tmpHandle = (Sck_Handle *)handle;
if (tmpHandle->p != NULL)
{
free(tmpHandle->p); //释放结构体 成员域的 指针所指向的内存空间
}
free(tmpHandle); //释放结构体内存
return 0;
}
- 添加MyDrive.h文件。
#ifndef _INC_MYDRIVE_H__
#define _INC_MYDRIVE_H__
#define Import_SSS
#ifdef Import_SSS
#define API _declspec(dllexport)
#else
#define API _declspec(dllimport)
#endif
#ifdef __cplusplus
extern "C" {
#endif
//1 数据类型的封装
//2 handle的概念: 底层库的内存资源,记录着函数运行的上下文信息..
//3 底层库提供的是一种机制, 而不是满足某一个人的策略
//完成发送报文的时候,进行数据加密
//定义函数指针类型 通过函数指针类型 来约定 厂商 去实现 加密解密函数的原型
typedef int(*EncData)(unsigned char *in, int inlen, unsigned char *out, int *outlen);
typedef int(*DecData)(unsigned char *in, int inlen, unsigned char *out, int *outlen);
API
int socketclient_init(void **handle);
API
int socketclient_send(void *handle, unsigned char *buf, int buflen);
API
int socketclient_sendAndEnc1(void *handle, unsigned char *buf, int buflen, EncData encDataCallback);
API
int socketclient_recv(void *handle, unsigned char *buf, int *buflen);
API
int socketclient_destory(void *handle);
#ifdef __cplusplus
}
#endif
#endif
完成后，右键项目，将配置类型改为dll动态链接库。
- 新建TestDrive工程，测试底层dll。将生成的RF_Drive.dll、RF_Drive.lib和MyDrive.h文件放到工程目录下面。
- 将RF_Drive链接到TestDrive。选择输入，然后选择附加依赖项，将RF_Drive.lib添加进去，然后点击确定。
- 将MyDrive.h包含到项目，然后新建Test.c文件，在Test.c中写入测试代码。代码如下：
思路：
在调用者实现加密算法Hw_EncData，不同的调用者，实现加密算法的方式不同，需要调用者自己实现，然后将函数的指针传递给底层驱动。
#define _CRT_SECURE_NO_WARNINGS
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "MyDrive.h"
int Hw_EncData(unsigned char *in, int inlen, unsigned char *out, int *outlen)
{
printf("func Hw_EncData begin....\n ");
strcpy((char *)out, "123456789");
*outlen = 9;
printf("func Hw_EncData end....\n ");
return 0;
}
void main()
{
unsigned char buf[1024];
int buflen;
unsigned char out[1024];
int outlen;
void *handle = NULL;
int ret = 0;
strcpy((char *)buf, "aaaaaaaaaffffffffdddddddd");
buflen = 9;
//客户端初始化 获取handle上下
ret = socketclient_init(&handle /*out*/);
if (ret != 0)
{
printf("func socketclient_init() err:%d \n ", ret);
goto End;
}
//客户端发报文
//ret = socketclient_send(handle /*in*/, buf /*in*/, buflen /*in*/);
ret = socketclient_sendAndEnc1(handle, buf, buflen, Hw_EncData);
if (ret != 0)
{
printf("func socketclient_send() err:%d \n ", ret);
goto End;
}
//客户端收报文
ret = socketclient_recv(handle /*in*/, out /*in*/, &outlen/*in out*/);
if (ret != 0)
{
printf("func socketclient_recv() err:%d \n ", ret);
goto End;
}
End:
//客户端释放资源
ret = socketclient_destory(handle/*in*/);
printf("hello...\n");
system("pause");
printf("hello...\n");
system("pause");
return;
}
运行结果如下：
代码：https://download.****.net/download/hhhhhhhhhhwwwwwwwwww/12898322