本文例項為大家分享了C++實現json形式的Socket傳輸圖片的具體程式碼，供大家參考，具體內容如下

大致流程：客戶端讀取圖片，經過Base64編碼，轉成字串的形式，儲存到json中，通過socket傳到服務端，然後Base64解碼，再轉換成圖片

一.服務端

1.main.cpp

#include <iostream>
#include <stdio.h>
#include "Base64_1.h"
#include <winsock2.h> 
#include "json1.hpp"
 
#pragma comment(lib,"ws2_32.lib") 
using json = nlohmann::json;
 
char revData[3888888];
 
bool WritePhotoFile(std::basic_string<TCHAR> strFileName,std::string &strData)
{
 HANDLE hFile;
 hFile = CreateFile(strFileName.c_str(),GENERIC_WRITE,NULL,CREATE_ALWAYS,FILE_ATTRIBUTE_NORMAL,NULL);
 
 if (hFile == INVALID_HANDLE_VALUE)
 {
 return false;
 }
 
 CBase64 base64;
 
 int datalen(0);
 DWORD dwritelen(0);
 std::string strdcode = base64.Decode(strData.data(),strData.size(),datalen);
 if (!WriteFile(hFile,strdcode.data(),datalen,&dwritelen,NULL))
 {
 CloseHandle(hFile);
 return false;
 }
 CloseHandle(hFile);
 return true;
}
 
 
 
int main(int argc,char* argv[])
{
 //初始化WSA 
 WORD sockVersion = MAKEWORD(2,2);
 WSADATA wsaData;
 if (WSAStartup(sockVersion,&wsaData) != 0)
 {
 return 0;
 }
 
 //建立套接字 
 SOCKET slisten = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
 if (slisten == INVALID_SOCKET)
 {
 printf("socket error !");
 return 0;
 }
 
 //繫結IP和埠 
 sockaddr_in sin;
 sin.sin_family = AF_INET;
 sin.sin_port = htons(8888);
 sin.sin_addr.S_un.S_addr = INADDR_ANY;
 
 if (bind(slisten,(LPSOCKADDR)&sin,sizeof(sin)) == SOCKET_ERROR)
 {
 printf("bind error !");
 }
 
 //開始監聽 
 if (listen(slisten,5) == SOCKET_ERROR)
 {
 printf("listen error !");
 return 0;
 }
 
 //迴圈接收資料 
 SOCKET sClient;
 sockaddr_in remoteAddr;
 int nAddrlen = sizeof(remoteAddr);
 
 //revData = (char*)malloc(sizeof(char) * 1000000);
 int i = 1;
 while (true)
 {
 printf("等待連線...\n");
 sClient = accept(slisten,(SOCKADDR *)&remoteAddr,&nAddrlen);
 if (sClient == INVALID_SOCKET)
 {
 printf("accept error !");
 continue;
 }
 printf("接受到一個連線：%s \r\n",inet_ntoa(remoteAddr.sin_addr));
 
 //接收資料 
 int ret = recv(sClient,revData,3888888,0);
 if (ret > 0)
 {
 revData[ret] = 0x00;
 json o = json::parse(revData);
 for (json::iterator it = o.begin(); it != o.end(); ++it) {
 //std::cout << it.key() << " : " << it.value() << "\n";
 if (it.key() == "imgA"|| it.key() == "imgB")
 {
 std::string num = std::to_string(i++);
 std::string strFileName = "D:\\"+ num +".jpg";
 std::string val = it.value();
 WritePhotoFile(strFileName,val);
 }
 
 }
 //std::cout<< json::parse(revData)<< std::endl;
 //printf(revData);
 }
 
 //傳送資料 
 //const char * sendData = "你好，TCP客戶端！\n";
 //send(sClient,sendData,strlen(sendData),0);
 closesocket(sClient);
 }
 
 
 closesocket(slisten);
 WSACleanup();
 
 return 0;
}

2.Base64.cpp

#include"Base64_1.h"
 
CBase64::CBase64()
{
 
}
 
CBase64::~CBase64()
{
 
}
 
std::string CBase64::Encode(const char* Data,int DataByte)
{
 //編碼表 
 const char EncodeTable[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 //返回值 
 std::string strEncode;
 unsigned char Tmp[4] = { 0 };
 int LineLength = 0;
 for (int i = 0; i<(int)(DataByte / 3); i++)
 {
 Tmp[1] = *Data++;
 Tmp[2] = *Data++;
 Tmp[3] = *Data++;
 strEncode += EncodeTable[Tmp[1] >> 2];
 strEncode += EncodeTable[((Tmp[1] << 4) | (Tmp[2] >> 4)) & 0x3F];
 strEncode += EncodeTable[((Tmp[2] << 2) | (Tmp[3] >> 6)) & 0x3F];
 strEncode += EncodeTable[Tmp[3] & 0x3F];
 if (LineLength += 4,LineLength == 76) { strEncode += "\r\n"; LineLength = 0; }
 }
 //對剩餘資料進行編碼 
 int Mod = DataByte % 3;
 if (Mod == 1)
 {
 Tmp[1] = *Data++;
 strEncode += EncodeTable[(Tmp[1] & 0xFC) >> 2];
 strEncode += EncodeTable[((Tmp[1] & 0x03) << 4)];
 strEncode += "==";
 }
 else if (Mod == 2)
 {
 Tmp[1] = *Data++;
 Tmp[2] = *Data++;
 strEncode += EncodeTable[(Tmp[1] & 0xFC) >> 2];
 strEncode += EncodeTable[((Tmp[1] & 0x03) << 4) | ((Tmp[2] & 0xF0) >> 4)];
 strEncode += EncodeTable[((Tmp[2] & 0x0F) << 2)];
 strEncode += "=";
 }
 
 return strEncode;
}
 
std::string CBase64::Decode(const char* Data,int DataByte,int& OutByte)
{
 //解碼錶 
 const char DecodeTable[] =
 {
 0,62,// '+' 
 0,63,// '/' 
 52,53,54,55,56,57,58,59,60,61,// '0'-'9' 
 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,// 'A'-'Z' 
 0,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,// 'a'-'z' 
 };
 //返回值 
 std::string strDecode;
 int nValue;
 int i = 0;
 while (i < DataByte)
 {
 if (*Data != '\r' && *Data != '\n')
 {
 nValue = DecodeTable[*Data++] << 18;
 nValue += DecodeTable[*Data++] << 12;
 strDecode += (nValue & 0x00FF0000) >> 16;
 OutByte++;
 if (*Data != '=')
 {
 nValue += DecodeTable[*Data++] << 6;
 strDecode += (nValue & 0x0000FF00) >> 8;
 OutByte++;
 if (*Data != '=')
 {
 nValue += DecodeTable[*Data++];
 strDecode += nValue & 0x000000FF;
 OutByte++;
 }
 }
 i += 4;
 }
 else// 回車換行,跳過 
 {
 Data++;
 i++;
 }
 }
 return strDecode;
}

3.Base64_1.h

//++Base64.h
 
#pragma once
#include <string>
 
 
class CBase64
{
public:
public:
 CBase64();
 ~CBase64();
 
 /*編碼
 DataByte
 [in]輸入的資料長度,以位元組為單位
 */
 std::string Encode(const char* Data,int DataByte);
 
 /*解碼
 DataByte
 [in]輸入的資料長度,以位元組為單位
 OutByte
 [out]輸出的資料長度,以位元組為單位,請不要通過返回值計算
 輸出資料的長度
 */
 std::string Decode(const char* Data,int& OutByte);
 
};

4.json.hpp 去網上下載吧，個人感覺比jsoncpp好用一些（我裡面的json1.hpp就是json.hpp）

二.客戶端

1.main.cpp

#include<WINSOCK2.H>
#include<STDIO.H>
#include<iostream>
#include<cstring>
#include <string>
#include <fstream>
#include "Bash64.h"
#include "json1.hpp"
 
using namespace std;
using json = nlohmann::json;
#pragma comment(lib,"ws2_32.lib")
 
char chBuf1[3888888],chBuf2[3888888];
 
int main()
{
 
 FILE *fIn1,*fIn2;
 int nRead1,nRead2;
 
 WORD sockVersion = MAKEWORD(2,2);
 WSADATA data;
 if (WSAStartup(sockVersion,&data) != 0)
 {
 return 0;
 }
 
 std::string num = std::to_string(1);
 std::string chFileIn1 = "E:\\"+num+".jpg";
 num = std::to_string(2);
 std::string chFileIn2 = "E:\\" + num + ".jpg";
 
 SOCKET sclient = socket(AF_INET,IPPROTO_TCP);
 if (sclient == INVALID_SOCKET)
 {
 printf("invalid socket!");
 return 0;
 }
 
 sockaddr_in serAddr;
 serAddr.sin_family = AF_INET;
 serAddr.sin_port = htons(8888);
 serAddr.sin_addr.S_un.S_addr = inet_addr("192.168.3.72");
 if (connect(sclient,(sockaddr *)&serAddr,sizeof(serAddr)) == SOCKET_ERROR)
 { //連線失敗 
 printf("connect error !");
 closesocket(sclient);
 return 0;
 }
 
 char chFileIn3[100],chFileIn4[100];
 strcpy(chFileIn3,chFileIn1.c_str());
 strcpy(chFileIn4,chFileIn2.c_str());
 fIn1 = fopen(chFileIn3,"rb");
 fIn2 = fopen(chFileIn4,"rb");
 if (fIn1 == NULL || fIn2 == NULL)
 {
 printf("開啟讀取檔案失敗");
 return 0;
 }
 //讀檔案
 json data1;
 
 //fread()讀取成功返回值為實際讀回的資料個數(單位為Byte)
 nRead1 = fread(chBuf1,sizeof(char),fIn1);
 nRead2 = fread(chBuf2,fIn2);
 //base64編碼 封裝進json
 string imgBase64_1 = base64_encode(chBuf1,nRead1);
 string imgBase64_2 = base64_encode(chBuf2,nRead2);
 data1["imgA"] = imgBase64_1;
 data1["imgB"] = imgBase64_2;
 fclose(fIn1);
 fclose(fIn2);
 
 //顯式轉換為string 
 std::string s = data1.dump();
 const char * sendData;
 sendData = s.c_str(); //string轉const char* 
 //char * sendData = "你好，TCP服務端，我是客戶端\n";
 send(sclient,0);
 
 //send()用來將資料由指定的socket傳給對方主機
 //int send(int s,const void * msg,int len,unsigned int flags)
 //s為已建立好連線的socket，msg指向資料內容，len則為資料長度，引數flags一般設0
 //成功則返回實際傳送出去的字元數，失敗返回-1，錯誤原因存於error 
 
 char recData[266680];
 int ret = recv(sclient,recData,266680,0);
 if (ret>0) {
 recData[ret] = 0x00;
 //printf(recData);
 }
 closesocket(sclient);
 
 WSACleanup();
 system("pause");
 return 0;
 
}

2.Bash64.h

#ifndef __BASE64_H__
#define __BASE64_H__
 
#include <iostream>
#include <string>
 
static const std::string base64_chars =
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/";
 
static inline bool is_base64(const char c)
{
 return (isalnum(c) || (c == '+') || (c == '/'));
}
 
std::string base64_encode(const char * bytes_to_encode,unsigned int in_len)
{
 std::string ret;
 int i = 0;
 int j = 0;
 unsigned char char_array_3[3];
 unsigned char char_array_4[4];
 
 while (in_len--)
 {
 char_array_3[i++] = *(bytes_to_encode++);
 if (i == 3)
 {
 char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
 char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
 char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
 char_array_4[3] = char_array_3[2] & 0x3f;
 for (i = 0; (i <4); i++)
 {
 ret += base64_chars[char_array_4[i]];
 }
 i = 0;
 }
 }
 if (i)
 {
 for (j = i; j < 3; j++)
 {
 char_array_3[j] = '\0';
 }
 
 char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
 char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
 char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
 char_array_4[3] = char_array_3[2] & 0x3f;
 
 for (j = 0; (j < i + 1); j++)
 {
 ret += base64_chars[char_array_4[j]];
 }
 
 while ((i++ < 3))
 {
 ret += '=';
 }
 
 }
 return ret;
}
 
std::string base64_decode(std::string const & encoded_string)
{
 int in_len = (int)encoded_string.size();
 int i = 0;
 int j = 0;
 int in_ = 0;
 unsigned char char_array_4[4],char_array_3[3];
 std::string ret;
 
 while (in_len-- && (encoded_string[in_] != '=') && is_base64(encoded_string[in_])) {
 char_array_4[i++] = encoded_string[in_]; in_++;
 if (i == 4) {
 for (i = 0; i <4; i++)
 char_array_4[i] = base64_chars.find(char_array_4[i]);
 
 char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
 char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
 char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];
 
 for (i = 0; (i < 3); i++)
 ret += char_array_3[i];
 i = 0;
 }
 }
 if (i) {
 for (j = i; j <4; j++)
 char_array_4[j] = 0;
 
 for (j = 0; j <4; j++)
 char_array_4[j] = base64_chars.find(char_array_4[j]);
 
 char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
 char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
 char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];
 
 for (j = 0; (j < i - 1); j++) ret += char_array_3[j];
 }
 
 return ret;
}
#endif

3.json.hpp 上面有連結（我裡面的json1.hpp就是json.hpp）

Hit:服務端和客戶端的Base64檔案不一樣，是因為當時服務端接收json時，Base64解碼成圖片出現了問題，又去找大神的部落格，把服務端的Base64檔案換了。然後能進行正常的傳輸圖片，客戶端就懶得換了~

以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支援我們。