转载自：嵌入式常用的设计模式——适配器模式的C语言实现 (qq.com)

一、介绍

适配器模式（Adapter Pattern）是作为多个不兼容的模块之间的桥梁。它结合了多个模块的功能。因C语言没有类和继承等特性，所以本文只讨论接口适配器，至于类适配器和对象适配器不在本文讨论范围。例如，在需要解码的程序中，一个上位机（用户）需要跟解码器通信，但是解码器需要能解码不同通信协议的数据包。

二、工作原理

将一个模块的接口转换成另一种接口，转换后的接口可以兼容。调用者（用户）不需要知道各模块内部的实现，方便增减模块，可以解耦，方便移植。

三、适配器图解

四、代码示例

//common.h

#define ADAPTER_PARAMS Protocol,param1 param2 param3 prarm4

typedef struct ProtocolStruct *Protocol;
typedef struct ProtocolInterfaceStruct *ProtocolInterface;

/**
 * Protocol interface structure
 */
struct ProtocolInterfaceStruct
{
    /*Parse function*/
    void (*Parse)(ADAPTER_PARAMS );

    /*Send function*/
    void (*Send)(ADAPTER_PARAMS );

    /*Bypass function*/
    void (*Receive)(ADAPTER_PARAMS );
};

/**
 * Protocol structure
 */
struct ProtocolStruct
{
    /*Protocol name*/
    const char *name;

    /*Protocol id*/
    TE_PRODUCT_ID protocol_id;

    /*Protocol interface*/
    ProtocolInterface vtable;
};

//protocol1.c

void protocol1_recv(ADAPTER_PARAMS )
{
    printf("protocol 1 receive.\r\n");
}

void protocol1_send(ADAPTER_PARAMS )
{
    printf("protocol 1 send.\r\n");
}

void protocol1_parse(ADAPTER_PARAMS )
{
    printf("protocol 1 parse.\r\n");
}

static struct ProtocolInterfaceStruct protocol1_interface=
{
    protocol1_parse,
    protocol1_send,
    protocol1_recv
};

static struct ProtocolStruct protocol1 =
{
    "protocol 1",
    protocol1,
    &protocol1_interface
}

//protocol2.c

void protocol2_recv(ADAPTER_PARAMS )
{
    printf("protocol 2 receive.\r\n");
}

void protocol2_send(ADAPTER_PARAMS )
{
    printf("protocol 2 send.\r\n");
}

void protocol2_parse(ADAPTER_PARAMS )
{
    printf("protocol 2 parse.\r\n");
}

static struct ProtocolInterfaceStruct protocol2_interface=
{
    protocol2_parse,
    protocol2_send,
    protocol2_recv
};

static struct ProtocolStruct protocol2 =
{
    "protocol 2",
    protocol2,
    &protocol2_interface
}

//protocol3.c

void protocol3_recv(ADAPTER_PARAMS )
{
    printf("protocol 3 receive.\r\n");
}

void protocol3_send(ADAPTER_PARAMS )
{
    printf("protocol 3 send.\r\n");
}

void protocol3_parse(ADAPTER_PARAMS )
{
    printf("protocol 3 parse.\r\n");
}

static struct ProtocolInterfaceStruct protocol3_interface=
{
    protocol3_parse,
    protocol3_send,
    protocol3_recv
};

static struct ProtocolStruct protocol3 =
{
    "protocol 3",
    protocol3,
    &protocol3_interface
}

//adapter.c

void protocol_parse(ADAPTER_PARAMS )
{
    if(Protocol != NULL)
    {
        Protocol->vtable->parse(ADAPTER_PARAMS );
    }
    else
    {
        //error
    }
}

void protocol_send(ADAPTER_PARAMS )
{
    if(Protocol != NULL)
    {
        Protocol->vtable->send(ADAPTER_PARAMS );
    }
    else
    {
        //error
    }
}

void protocol_recv(ADAPTER_PARAMS )
{
    if(Protocol != NULL)
    {
        Protocol->vtable->recv(ADAPTER_PARAMS );
    }
    else
    {
        //error
    }
}