C++中的通用结构定义，及相应的序列化、反序列化接口

一个通用的C++结构定义如下：

typedef struct tagCommonStruct {
    long len;
    void* buff;
}CommonStruct_st;

此接口对应的普通序列化、反序列化接口如下：

unsigned char* EncodeCommonStruct(const CommonStruct_st& CommonSt)
{
    //分配内存
    unsigned char* strBuff = (unsigned char*)malloc(CALC_COMMON_ST_LEN(&CommonSt));
    if (NULL == strBuff) 
    {
        return NULL;
    }

    //填充内容
    *(long*)strBuff = CommonSt.len;
    if (CommonSt.len > 0) {
        memcpy(strBuff + sizeof(long), CommonSt.buff, CommonSt.len);
    }

    return strBuff;
}

BOOL DecodeCommonStruct(const unsigned char* strBuff, long len, CommonStruct_st& CommonSt)
{
    long st_len;
    if (NULL == strBuff) 
    {
        return FALSE;
    }

    //获取到当前长度
    st_len = *(const long*)strBuff;
    //校验BUFF内容合法性
    if (st_len + sizeof(long) > len) {
        return FALSE;
    }
    CommonSt.len = st_len;
    CommonSt.buff = (void*)malloc(st_len);
    memcpy(CommonSt.buff, strBuff + sizeof(long), st_len);
    return TRUE;
}

void EncodeCommonStruct_S(const CommonStruct_st& CommonSt, std::string& strOut)
{
    //分配内存
    strOut.resize(CALC_COMMON_ST_LEN(&CommonSt));

    //填充内容
    *(long*)&(strOut[0]) = CommonSt.len;
    if (CommonSt.len > 0) {
        memcpy(&(strOut[0]) + sizeof(long), CommonSt.buff, CommonSt.len);
    }

    return;
}

BOOL DecodeCommonStruct_S(const unsigned char* strBuff, long len, CommonStruct_st& pCommonSt, std::string& strInnBuff)
{
    long st_len;
    if (NULL == strBuff) 
    {
        return FALSE;
    }

    //获取到当前长度
    st_len = *(const long*)strBuff;
    //校验BUFF内容合法性
    if (st_len + sizeof(long) > len) {
        return FALSE;
    }
    pCommonSt.len = st_len;
    strInnBuff.resize(st_len);
    //pCommonSt.buff = (void*)malloc(st_len);
    pCommonSt.buff = &strInnBuff[0];
    memcpy(pCommonSt.buff, strBuff + sizeof(long), st_len);
    return TRUE;
}

支持批量操作的序列化、反序列化接口：

#define MAX_COMMON_STRUCT_PARAM_NUMBER (16)

void EncodeCommonStructV(std::string& strOut, int nStNum, ...)
{
    int index = 0;
    int nBufLen;
    unsigned char* strTemp;
    //最多允许16个
    va_list arg_ptr;
    CommonStruct_st CommStructStArray[MAX_COMMON_STRUCT_PARAM_NUMBER];

    //
    if (nStNum > MAX_COMMON_STRUCT_PARAM_NUMBER) {
        return;
    }

    //依次取出相应的结构、指针位置
    nBufLen = 0;
    va_start(arg_ptr, nStNum);
    for(index = 0; index < nStNum; index ++){
        CommStructStArray[index].len = va_arg(arg_ptr, int);
        CommStructStArray[index].buff = va_arg(arg_ptr, void*);
        nBufLen += CALC_COMMON_ST_LEN(&CommStructStArray[index]);
    }
    va_end(arg_ptr);

    //计算总字符长度
    strOut.resize(nBufLen, '');
    strTemp = (unsigned char*)&strOut[0];

    //依次格式化
    std::string strTmpBuf;
    for(index = 0; index < nStNum; index ++){
#if 0
        EncodeCommonStruct_S(CommStructStArray[index],  strTmpBuf);
        memcpy(strTemp, strTmpBuf.c_str(), CALC_COMMON_ST_LEN(&CommStructStArray[index]);
#else
        *(long*)strTemp = CommStructStArray[index].len;
        if (CommStructStArray[index].len > 0) {
            memcpy(strTemp + sizeof(long), CommStructStArray[index].buff, CommStructStArray[index].len);
        }
#endif

        strTemp += CALC_COMMON_ST_LEN(&CommStructStArray[index]);
    }
}

BOOL DecodeCommonStructV(const unsigned char* strBuff, long len, ...)
{
    va_list arg_ptr;
    long leave_len, st_len;
    CommonStruct_st *pstCommonStruct;
    const unsigned char* strTemp;
    if (NULL == strBuff) 
    {
        return FALSE;
    }

    leave_len = len;
    strTemp = strBuff;
    va_start(arg_ptr, len);
    while(leave_len > 0){
        pstCommonStruct = va_arg(arg_ptr, CommonStruct_st *);

        //允许BUFF中的内容更长，但只取前面一部分
        if (NULL == pstCommonStruct){
            break;
        }

        //获取到当前长度
        st_len = *(const long*)strTemp;
        //校验BUFF内容合法性
        if (st_len + sizeof(long) > leave_len) {
            return FALSE;
        }

        //填充一块结构体的内容
        pstCommonStruct->len = st_len;
        memcpy(pstCommonStruct->buff, strTemp + sizeof(long), st_len);

        //偏移位置
        strTemp += st_len + sizeof(long);
        leave_len -= st_len + sizeof(long);
    }
    va_end(arg_ptr);

    return TRUE;
}

V2版本的 EncodeCommonStruct，不再限制传入参数的最多个数

void EncodeCommonStructV2(std::string& strOut, int nStNum, ...)
{
    int index = 0;
    int nBufLen;
    va_list arg_ptr;
    unsigned char* strTemp;
    CommonStruct_st stCommStruct;

    //依次取出相应的结构、指针位置
    nBufLen = 0;
    va_start(arg_ptr, nStNum);
    for(index = 0; index < nStNum; index ++){
        stCommStruct.len = va_arg(arg_ptr, int);
        stCommStruct.buff = va_arg(arg_ptr, void*);
        nBufLen += CALC_COMMON_ST_LEN(&stCommStruct);
    }
    va_end(arg_ptr);

    //计算总字符长度
    strOut.resize(nBufLen, '');
    strTemp = (unsigned char*)&strOut[0];

    //依次格式化
    std::string strTmpBuf;
    va_start(arg_ptr, nStNum);
    for(index = 0; index < nStNum; index ++){
        stCommStruct.len = va_arg(arg_ptr, int);
        stCommStruct.buff = va_arg(arg_ptr, void*);
        *(long*)strTemp = stCommStruct.len;
        if (stCommStruct.len > 0) {
            memcpy(strTemp + sizeof(long), stCommStruct.buff, stCommStruct.len);
        }

        strTemp += CALC_COMMON_ST_LEN(&stCommStruct);
    }
    va_end(arg_ptr);
}

 V2版本的 DecodeCommonStruct，不再限制传入参数的最多个数

BOOL DecodeCommonStructV2(const unsigned char* strBuff, std::string& strInnBuff, long len, ...)
{
    va_list arg_ptr;
    long leave_len, st_len, all_st_len;
    CommonStruct_st *pstCommonStruct;
    const unsigned char* strTemp;
    unsigned char* strDest;
    if (NULL == strBuff) 
    {
        return FALSE;
    }

    //计算strBuff中总共需要多少内存来存放
    all_st_len = 0;
    leave_len = len;
    strTemp = strBuff;
    while (leave_len > 0){
        //获取到当前长度
        st_len = *(const long*)strTemp;
        //校验BUFF内容合法性
        if (st_len + sizeof(long) > leave_len) {
            return FALSE;
        }
        //每个都用隔开吧
        all_st_len += st_len + 1;

        strTemp += st_len + sizeof(long);
        leave_len -= st_len + sizeof(long);
    }

    //分配内存
    strInnBuff.resize(all_st_len, '');
    strDest = (unsigned char*)&strInnBuff[0];

    strTemp = strBuff;
    leave_len = len;
    va_start(arg_ptr, len);
    while(leave_len > 0){
        pstCommonStruct = va_arg(arg_ptr, CommonStruct_st *);

        //允许BUFF中的内容更长，但只取前面一部分
        if (NULL == pstCommonStruct){
            break;
        }

        //获取到当前长度
        st_len = *(const long*)strTemp;

        //填充一块结构体的内容
        pstCommonStruct->len = st_len;
        pstCommonStruct->buff = strDest;
        //拷贝至缓冲区中
        memcpy(strDest, strTemp + sizeof(long), st_len);

        //偏移位置
        strTemp += st_len + sizeof(long);
        leave_len -= st_len + sizeof(long);
        strDest += st_len + 1;
    }
    va_end(arg_ptr);

    return TRUE;
}