C++实现二进制序列化/反序列化

背景

涉及对象传输或存储时，均需要序列化的参与，将对象转为连续的二进制数据后才能进行传输或存储，需要还原对象时，通过反序列化逆向处理二进制数据遍能得到原对象

这里的对象是一种广泛的概念，往大了说就是一段有意义的内存

实现

实现过程中主要使用模板应对各种类型，特化+宏应对基础数据类型，逐层处理应对STL容器嵌套情况
C++语言本身不带反射，自定义结构需继承接口类Serializable，并实现相应接口
实现时使用了std::move()进行构造与赋值，自定义结构最好实现自己的移动构造函数与移动赋值函数
获取序列化buffer时，先计算序列化目标在序列化后的总字节数，一次性申请足够内存
获取序列化buffer时，返回的buffer之前藏了序列化目标的总字节数，藏东西这招跟redis学的
藏的目标总字节数目的用于，反序列化前简单判断待反序列化buffer是否有效
未支持指针类型，传递错误类型的指针(强转目标类型与实际类型不符合)会导致内存错误，序列化过程中没法判断类型是否正确
未支持C风格字符串，C风格字符串以0结尾，非二进制安全
需要序列化一段连续内存时，构造std::string后传入
反序列化时，调用者需自行保证，待反序列化buffer的原始类型与目标类型一致，代码不能识别出类型差异与结构改变
使用方式 申请序列化buffer->序列化->三方库压缩->三方库加密->传输/落盘->接收/读取->三方库解密->三方库解压->简单检查->反序列化->释放buffer
序列化后的数据格式如下
- 先写入对象序列化后总长度，后面才接着写入对象序列化数据
  - 对象是基础类型则直接写入数据
  - 对象是STL容器先写入元素个数，再写入每个元素序列化数据
    - 如果元素是std::pairl类型，则先写入序列化Key，再写入序列化Value
  - 对象是自定义结构，则需用户定义数据格式

总体结构：

对象序列化后总长度	对象序列化数据

对象是基础数据：

对象序列化后总长度	对象序列化数据(charintshortlong.........)

对象是STL容器：

对象序列化后总长度	元素个数	元素1序列化数据	元素2序列化数据	元素3序列化数据	.....	元素n序列化数据

对象是STL容器之Map：

对象序列化后总长度	元素个数	Pair 1之Key序列化数据	Pair 1之Value序列化数据	.....	Pair n之Key序列化数据	Pair n之Value序列化数据

代码

#ifndef _Serialization_H_
#define _Serialization_H_

#include <map>
#include <set>
#include <list>
#include <string>
#include <vector>

//基础数据长度计算
#define BASIC_DATA_LENGTH(BasicType)                                            
    template<>                                                                  
    static unsigned Length(const BasicType& elem){                              
        return sizeof(elem);                                                    
    }                                        

    //申请用于序列化的buffer         总格式    |数据总长度|数据|
#define MAKE_BUFFER(uLen){                                                      
        char *pBuffer = new char[uLen + sizeof(LEN)];                           
        if(nullptr == pBuffer){                                                 
            return nullptr;                                                     
        }                                                                       
        *reinterpret_cast<LEN *const>(pBuffer) = uLen;                          
        return pBuffer + sizeof(LEN);                                           
    }

    //基础数据序列化buffer获取
#define BASIC_DATA_GET_BUFFER(BasicType)                                        
    template<>                                                                  
    static char *const GetBuffer(const BasicType& elem){                        
        LEN uLen = sizeof(elem);                                                
        MAKE_BUFFER(uLen);                                                      
    }

    //基础数据序列化主体
#define BASIC_DATA_SERIALIZE(BasicType)                                         
    template<>                                                                  
    static unsigned Serialize(const BasicType& elem, char *const pBuffer){      
        ::memcpy(pBuffer, &elem, sizeof(BasicType));                            
        return sizeof(BasicType);                                               
    }

    //基础数据反序列化主体
#define BASIC_DATA_UNSERIALIZE(BasicType)                                       
    template<>                                                                  
    static unsigned UnSerialize(const char *const pBuffer, BasicType& elem){    
        ::memcpy(&elem, pBuffer, sizeof(BasicType));                            
        return sizeof(BasicType);                                               
    }

namespace Serialization{

    //存放长度信息类型
    using LEN = unsigned;

    //自定义结构序列化基类
    class Serializable{
    public:
        virtual unsigned Length() const = 0;
        virtual unsigned Serialize(char *const pBuffer) const = 0;
        virtual unsigned UnSerialize(const char *const pBuffer) = 0;
        virtual ~Serializable(){};
    };

    /*
        前项声明部分，STL容器嵌套编译问题
    */
    template<typename Elem>
    unsigned Length(const std::list<Elem>& list);
    template<typename Key, typename Value>
    unsigned Length(const std::map<Key, Value>& map);
    template<typename Elem>
    unsigned Length(const std::vector<Elem>& vec);
    template<typename Elem>
    unsigned Length(const std::set<Elem>& set);

    template<typename Elem>
    char *const GetBuffer(const std::list<Elem>& list);
    template<typename Key, typename Value>
    char *const GetBuffer(const std::map<Key, Value>& map);
    template<typename Elem>
    char *const GetBuffer(const std::vector<Elem>& vec);
    template<typename Elem>
    char *const GetBuffer(const std::set<Elem>& set);

    template<typename Elem>
    unsigned Serialize(const std::list<Elem>& list, char *const pBuffer);
    template<typename Key, typename Value>
    unsigned Serialize(const std::map<Key, Value>& map, char *const pBuffer);
    template<typename Elem>
    unsigned Serialize(const std::vector<Elem>& vec, char *const pBuffer);
    template<typename Elem>
    unsigned Serialize(const std::set<Elem>& set, char *const pBuffer);

    template<typename Elem>
    unsigned UnSerialize(const char* pBuffer, std::list<Elem>& list);
    template<typename Key, typename Value>
    unsigned UnSerialize(const char* pBuffer, std::map<Key, Value>& map);
    template<typename Elem>
    unsigned UnSerialize(const char* pBuffer, std::vector<Elem>& vec);
    template<typename Elem>
    unsigned UnSerialize(const char* pBuffer, std::set<Elem>& set);

    /*
        长度计算部分
        得到数据长度
    */
    template<typename Elem>
    static unsigned Length(const Elem& elem){
        return elem.Length();
    }

    BASIC_DATA_LENGTH(char)
        BASIC_DATA_LENGTH(short)
        BASIC_DATA_LENGTH(int)
        BASIC_DATA_LENGTH(float)
        BASIC_DATA_LENGTH(long)
        BASIC_DATA_LENGTH(double)
        BASIC_DATA_LENGTH(long long)
        BASIC_DATA_LENGTH(unsigned char)
        BASIC_DATA_LENGTH(unsigned short)
        BASIC_DATA_LENGTH(unsigned int)
        BASIC_DATA_LENGTH(unsigned long)
        BASIC_DATA_LENGTH(unsigned long long)

        template<>
    static unsigned Length(const std::string& str){
        return sizeof(LEN) + static_cast<unsigned>(str.size());                //容器对象 格式 |元素个数|数据|
    }

    template<typename Elem>
    static unsigned Length(const std::list<Elem>& list){
        LEN uLen = 0;
        for(const auto& elem : list){
            uLen += Length(elem);
        }
        return sizeof(LEN) + uLen;
    }

    template<typename Key, typename Value>
    static unsigned Length(const std::map<Key, Value>& map){
        LEN uLen = 0;
        for(const auto& elem : map){
            uLen += Length(elem.first);
            uLen += Length(elem.second);
        }
        return sizeof(LEN) + uLen;
    }

    template<typename Elem>
    static unsigned Length(const std::vector<Elem>& vec){
        LEN uLen = 0;
        for(const auto& elem : vec){
            uLen += Length(elem);
        }
        return sizeof(LEN) + uLen;
    }

    template<typename Elem>
    static unsigned Length(const std::set<Elem>& set){
        LEN uLen = 0;
        for(const auto& elem : set){
            uLen += Length(elem);
        }
        return sizeof(LEN) + uLen;
    }

    /*
        buffer申请、释放部分
        一次性申请足够内存
    */
    template<typename Elem>
    static char *const GetBuffer(const Elem& elem){
        LEN uLen = elem.Length();
        MAKE_BUFFER(uLen);
    }

    BASIC_DATA_GET_BUFFER(char)
        BASIC_DATA_GET_BUFFER(short)
        BASIC_DATA_GET_BUFFER(int)
        BASIC_DATA_GET_BUFFER(float)
        BASIC_DATA_GET_BUFFER(long)
        BASIC_DATA_GET_BUFFER(double)
        BASIC_DATA_GET_BUFFER(long long)
        BASIC_DATA_GET_BUFFER(unsigned char)
        BASIC_DATA_GET_BUFFER(unsigned short)
        BASIC_DATA_GET_BUFFER(unsigned int)
        BASIC_DATA_GET_BUFFER(unsigned long)
        BASIC_DATA_GET_BUFFER(unsigned long long)

        template<>
    static char *const GetBuffer(const std::string& str){
        LEN uLen = Length(str);
        MAKE_BUFFER(uLen);
    }

    template<typename Elem>
    static char *const GetBuffer(const std::list<Elem>& list){
        LEN uLen = Length(list);
        MAKE_BUFFER(uLen);
    }

    template<typename Key, typename Value>
    static char *const GetBuffer(const std::map<Key, Value>& map){
        LEN uLen = Length(map);
        MAKE_BUFFER(uLen);
    }

    template<typename Elem>
    static char *const GetBuffer(const std::vector<Elem>& vec){
        LEN uLen = Length(vec);
        MAKE_BUFFER(uLen);
    }

    template<typename Elem>
    static char *const GetBuffer(const std::set<Elem>& set){
        LEN uLen = Length(set);
        MAKE_BUFFER(uLen);
    }

    static void ReleaseBuffer(char *const pBuffer){
        delete[] (pBuffer - sizeof(LEN));
    }

    /*
        序列化部分
    */
    template<typename Elem>
    static unsigned Serialize(const Elem& elem, char *const pBuffer){
        return elem.Serialize(pBuffer);
    }

    BASIC_DATA_SERIALIZE(char)
        BASIC_DATA_SERIALIZE(short)
        BASIC_DATA_SERIALIZE(int)
        BASIC_DATA_SERIALIZE(float)
        BASIC_DATA_SERIALIZE(long)
        BASIC_DATA_SERIALIZE(double)
        BASIC_DATA_SERIALIZE(long long)
        BASIC_DATA_SERIALIZE(unsigned char)
        BASIC_DATA_SERIALIZE(unsigned short)
        BASIC_DATA_SERIALIZE(unsigned int)
        BASIC_DATA_SERIALIZE(unsigned long)
        BASIC_DATA_SERIALIZE(unsigned long long)

        template<>
    static unsigned Serialize(const std::string& str, char* const pBuffer){
        *reinterpret_cast<LEN *const>(pBuffer) = static_cast<LEN>(str.size());            //元素个数
        ::memcpy(pBuffer + sizeof(LEN), str.data(), str.size());                        //数据
        return static_cast<unsigned>(str.size()) + sizeof(LEN);
    }

    template<typename Elem>
    static unsigned Serialize(const std::list<Elem>& list, char *const pBuffer){
        unsigned uPos = sizeof(LEN);
        *reinterpret_cast<LEN *const>(pBuffer) = static_cast<LEN>(list.size());            //元素个数
        for(const auto& elem : list){
            uPos += Serialize(elem, pBuffer + uPos);
        }
        return uPos;
    }

    template<typename Key, typename Value>
    static unsigned Serialize(const std::map<Key, Value>& map, char *const pBuffer){
        unsigned uPos = sizeof(LEN);
        *reinterpret_cast<LEN *const>(pBuffer) = static_cast<LEN>(map.size());            //元素个数
        for(const auto& elem : map){
            uPos += Serialize(elem.first, pBuffer + uPos);
            uPos += Serialize(elem.second, pBuffer + uPos);
        }
        return uPos;
    }

    template<typename Elem>
    static unsigned Serialize(const std::vector<Elem>& vec, char *const pBuffer){
        unsigned uPos = sizeof(LEN);
        *reinterpret_cast<LEN *const>(pBuffer) = static_cast<LEN>(vec.size());            //元素个数
        for(const auto& elem : vec){
            uPos += Serialize(elem, pBuffer + uPos);
        }
        return uPos;
    }

    template<typename Elem>
    static unsigned Serialize(const std::set<Elem>& set, char *const pBuffer){
        unsigned uPos = sizeof(LEN);
        *reinterpret_cast<LEN *const>(pBuffer) = static_cast<LEN>(set.size());            //元素个数
        for(const auto& elem : set){
            uPos += Serialize(elem, pBuffer + uPos);
        }
        return uPos;
    }

    /*
        检查反序列化之前的buffer
        BufferLen指包含数据总长度在内的长度，即从硬盘上读取并解压缩后的整个buffer长度
    */
    static int CheckLength(const char *const pBuffer, int BufferLen){
        if(*reinterpret_cast<const LEN *const>(pBuffer - sizeof(LEN)) + sizeof(LEN) != BufferLen){
            return 0;
        }
        return 1;
    }

    /*
        反序列化部分
    */
    template<typename Elem>
    static unsigned UnSerialize(const char* pBuffer, Elem& elem){
        return elem.UnSerialize(pBuffer);
    }

    BASIC_DATA_UNSERIALIZE(char)
        BASIC_DATA_UNSERIALIZE(short)
        BASIC_DATA_UNSERIALIZE(int)
        BASIC_DATA_UNSERIALIZE(float)
        BASIC_DATA_UNSERIALIZE(long)
        BASIC_DATA_UNSERIALIZE(double)
        BASIC_DATA_UNSERIALIZE(long long)
        BASIC_DATA_UNSERIALIZE(unsigned char)
        BASIC_DATA_UNSERIALIZE(unsigned short)
        BASIC_DATA_UNSERIALIZE(unsigned int)
        BASIC_DATA_UNSERIALIZE(unsigned long)
        BASIC_DATA_UNSERIALIZE(unsigned long long)

        template<>
    static unsigned UnSerialize(const char* pBuffer, std::string& str){
        LEN uLen = *reinterpret_cast<const LEN *>(pBuffer);
        std::string strTemp(pBuffer + sizeof(LEN), uLen);
        str = std::move(strTemp);
        return uLen + sizeof(LEN);
    }

    template<typename Elem>
    static unsigned UnSerialize(const char* pBuffer, std::list<Elem>& list){
        LEN uLen = *reinterpret_cast<const LEN *>(pBuffer);
        unsigned uPos = sizeof(LEN);
        for(LEN i = 0; i < uLen; i++){
            Elem elem;
            uPos += UnSerialize(pBuffer + uPos, elem);
            list.push_back(std::move(elem));
        }
        return uPos;
    }

    template<typename Key, typename Value>
    static unsigned UnSerialize(const char* pBuffer, std::map<Key, Value>& map){
        LEN uLen = *reinterpret_cast<const LEN *>(pBuffer);
        unsigned uPos = sizeof(LEN);
        for(LEN i = 0; i < uLen; i++){
            Key key;
            Value val;
            uPos += UnSerialize(pBuffer + uPos, key);
            uPos += UnSerialize(pBuffer + uPos, val);
            map.insert(std::make_pair(std::move(key), std::move(val)));
        }
        return uPos;
    }

    template<typename Elem>
    static unsigned UnSerialize(const char* pBuffer, std::vector<Elem>& vec){
        LEN uLen = *reinterpret_cast<const LEN *>(pBuffer);
        vec.resize(uLen);
        unsigned uPos = sizeof(LEN);
        for(LEN i = 0; i < uLen; i++){
            Elem elem;
            uPos += UnSerialize(pBuffer + uPos, elem);
            vec[i] = std::move(elem);
        }
        return uPos;
    }

    template<typename Elem>
    static unsigned UnSerialize(const char* pBuffer, std::set<Elem>& set){
        LEN uLen = *reinterpret_cast<const LEN *>(pBuffer);
        unsigned uPos = sizeof(LEN);
        for(LEN i = 0; i < uLen; i++){
            Elem elem;
            uPos += UnSerialize(pBuffer + uPos, elem);
            set.emplace(std::move(elem));
        }
        return uPos;
    }
};
#endif // !_Serialization_H_

测试代码

#include <cstdlib>
#include <cassert>
#include <iostream>

#include "Serialization.h"

template<typename T>
void Test(const T& a){
    std::cout << Serialization::Length(a) << std::endl;

    auto pBuffer = Serialization::GetBuffer(a);

    auto len = Serialization::Serialize(a, pBuffer);
    std::cout << len << std::endl;

    assert(1 == Serialization::CheckLength(pBuffer, Serialization::Length(a) + sizeof(Serialization::LEN)));

    T b = T();
    len = Serialization::UnSerialize(pBuffer, b);
    std::cout << len << std::endl;

    Serialization::ReleaseBuffer(pBuffer);
    assert(a == b);
}

class MyTest : public Serialization::Serializable{
public:
    MyTest() : m_i(0), m_c(0), m_d(0){}

    MyTest(int i, char c, double d, const std::string& str, const std::list<int>& list,
        const std::map<int, double>& map, const std::vector<int>& vec, const std::set<int>& set)
        :m_i(i), m_c(c), m_d(d), m_str(str), m_list(list), m_map(map), m_vec(vec), m_set(set){}

    MyTest(int i, char c, double d, std::string&& str, std::list<int>&& list,
        std::map<int, double>&& map, std::vector<int>&& vec, std::set<int>&& set)        //针对列表初始化
        :m_i(i), m_c(c), m_d(d), m_str(std::move(str)), m_list(std::move(list)), m_map(std::move(map)), m_vec(std::move(vec)), m_set(std::move(set)){}

    bool operator==(const MyTest& rhs) const{
        return m_i == rhs.m_i && m_c == rhs.m_c && m_d == rhs.m_d && m_str == rhs.m_str && m_list == rhs.m_list && m_map == rhs.m_map && m_vec == rhs.m_vec && m_set == rhs.m_set;
    }

    virtual unsigned Length() const override{
        return Serialization::Length(m_i) + Serialization::Length(m_c) + Serialization::Length(m_d) + Serialization::Length(m_str) + Serialization::Length(m_list)
            + Serialization::Length(m_map) + Serialization::Length(m_vec) + Serialization::Length(m_set);
    }
    virtual unsigned Serialize(char *const pBuffer) const override{
        unsigned uPos = 0;
        uPos += Serialization::Serialize(m_i, pBuffer + uPos);
        uPos += Serialization::Serialize(m_c, pBuffer + uPos);
        uPos += Serialization::Serialize(m_d, pBuffer + uPos);
        uPos += Serialization::Serialize(m_str, pBuffer + uPos);
        uPos += Serialization::Serialize(m_list, pBuffer + uPos);
        uPos += Serialization::Serialize(m_map, pBuffer + uPos);
        uPos += Serialization::Serialize(m_vec, pBuffer + uPos);
        uPos += Serialization::Serialize(m_set, pBuffer + uPos);
        return  uPos;
    }
    virtual unsigned UnSerialize(const char *const pBuffer)override{
        unsigned uPos = 0;
        uPos += Serialization::UnSerialize(pBuffer + uPos, m_i);
        uPos += Serialization::UnSerialize(pBuffer + uPos, m_c);
        uPos += Serialization::UnSerialize(pBuffer + uPos, m_d);
        uPos += Serialization::UnSerialize(pBuffer + uPos, m_str);
        uPos += Serialization::UnSerialize(pBuffer + uPos, m_list);
        uPos += Serialization::UnSerialize(pBuffer + uPos, m_map);
        uPos += Serialization::UnSerialize(pBuffer + uPos, m_vec);
        uPos += Serialization::UnSerialize(pBuffer + uPos, m_set);
        return uPos;
    }

private:
    int m_i;
    char m_c;
    double m_d;
    std::string m_str;
    std::list<int> m_list;
    std::map<int, double> m_map;
    std::vector<int> m_vec;
    std::set<int> m_set;
};



int main(int argc, char** argv){
    //基础类型
    Test<char>('a');
    Test<short>(-1);
    Test<int>(-1);
    Test<float>(-1.0);
    Test<long>(-1);
    Test<double>(-1.0);
    Test<long long>(-1);
    Test<unsigned char>(1);
    Test<unsigned short>(1);
    Test<unsigned int>(1);
    Test<unsigned long>(1);
    Test<unsigned long long>(1);

    //STL容器
    Test<std::string>("Test!!!");
    Test<std::list<int>>({1, 2, 3, 4, 5, 6});
    Test<std::map<int, double>>({{1, 1.0}, {2, 2.0}, {3, 3.0}});
    Test<std::vector<int>>({1, 2, 3, 4, 5, 6});
    Test<std::set<int>>({1, 2, 3, 4, 5, 6});

    //STL容器嵌套
    Test<std::set<std::string>>({"test1", "test2", "test3"});
    Test<std::list<std::set<std::string>>>({{"test1", "test2", "test3"}, {"test1", "test2", "test3"}, {"test1", "test2", "test3"}});
    Test<std::map<int, std::list<std::set<std::string>>>>({{1, {{"test1", "test2", "test3"}, {"test1", "test2", "test3"}, {"test1", "test2", "test3"}}},
        {2, {{"test1", "test2", "test3"}, {"test1", "test2", "test3"}, {"test1", "test2", "test3"}}},
        {3, {{"test1", "test2", "test3"}, {"test1", "test2", "test3"}, {"test1", "test2", "test3"}}}});
    Test<std::vector<std::map<int, std::list<std::set<std::string>>>>>({{{1, {{"test1", "test2", "test3"}, {"test1", "test2", "test3"}, {"test1", "test2", "test3"}}},
        {2, {{"test1", "test2", "test3"}, {"test1", "test2", "test3"}, {"test1", "test2", "test3"}}},
        {3, {{"test1", "test2", "test3"}, {"test1", "test2", "test3"}, {"test1", "test2", "test3"}}}},
        {{1, {{"test1", "test2", "test3"}, {"test1", "test2", "test3"}, {"test1", "test2", "test3"}}},
        {2, {{"test1", "test2", "test3"}, {"test1", "test2", "test3"}, {"test1", "test2", "test3"}}},
        {3, {{"test1", "test2", "test3"}, {"test1", "test2", "test3"}, {"test1", "test2", "test3"}}}},
        {{1, {{"test1", "test2", "test3"}, {"test1", "test2", "test3"}, {"test1", "test2", "test3"}}},
        {2, {{"test1", "test2", "test3"}, {"test1", "test2", "test3"}, {"test1", "test2", "test3"}}},
        {3, {{"test1", "test2", "test3"}, {"test1", "test2", "test3"}, {"test1", "test2", "test3"}}}}});

    //自定义结构
    MyTest test(1, 'a', 1.0, "Test!!!", {1, 2, 3, 4, 5, 6}, {{1, 1.0}, {2, 2.0}, {3, 3.0}}, {1, 2, 3, 4, 5, 6}, {1, 2, 3, 4, 5, 6});
    Test<MyTest>(test);

    system("pause");
    return 0;
}

改进

在序列化后总长度前方增加两个字段
- 字段一：特定标识字符串，用于直接判断buffer是否是可序列化内存，如rdb文件开头就有"REDIS"
- 字段二：增加校验和字段，存储序列化后数据的校验和，用于检查序列化数据是否被篡改，如网络协议上一般都会有此字段

无法增加协议版本号，因为自定义结构的序列化、反序列化由用户控制，无法统一决定版本

来自为知笔记(Wiz)

原创不易，转载请注明出处，谢谢

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原文地址：https://www.cnblogs.com/Keeping-Fit/p/14952742.html

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