通过C++调用Windows api学习post请求的发送

2025-03-07  本文已影响0人  AI_Finance

下面的代码使用windows api的unicode函数实现了一个http post请求；本文为希望学习windows网络编程的人深度解读下面的代码

#include <windows.h>
#include <string>
#include <sstream>
#include <iostream>
#include <wininet.h>

// 自定义 UTF-8 转 UTF-16
std::wstring ConvertToWideString(const char* utf8String) {
    if (!utf8String) return L"";
    int wideLength = MultiByteToWideChar(CP_UTF8, 0, utf8String, -1, NULL, 0);
    std::wstring wideString(wideLength, 0);
    MultiByteToWideChar(CP_UTF8, 0, utf8String, -1, &wideString[0], wideLength);
    return wideString;
}

// 自定义 UTF-16 转 UTF-8
std::string ConvertToUTF8(const wchar_t* wideString) {
    if (!wideString) return "";
    int utf8Length = WideCharToMultiByte(CP_UTF8, 0, wideString, -1, NULL, 0, NULL, NULL);
    std::string utf8String(utf8Length, 0);
    WideCharToMultiByte(CP_UTF8, 0, wideString, -1, &utf8String[0], utf8Length, NULL, NULL);
    return utf8String;
}

// 将整数转换为宽字符串
std::wstring ToWString(size_t value) {
    std::wstringstream wss;
    wss << value;
    return wss.str();
}

// 使用 Windows API 写入日志
void WriteLog(const std::string& message) {
    const wchar_t* logFileName = L"chriszhao_Debug.log";

    HANDLE hFile = CreateFileW(
        logFileName,
        FILE_APPEND_DATA,
        FILE_SHARE_READ,
        NULL,
        OPEN_ALWAYS,
        FILE_ATTRIBUTE_NORMAL,
        NULL
    );

    if (hFile == INVALID_HANDLE_VALUE) {
        std::cerr << "Failed to open log file: " << ConvertToUTF8(logFileName) << std::endl;
        return;
    }

    DWORD bytesWritten = 0;
    WriteFile(hFile, message.c_str(), message.size(), &bytesWritten, NULL);
    WriteFile(hFile, "\\n", 1, &bytesWritten, NULL);
    CloseHandle(hFile);
}

// 导出函数声明
extern "C" __declspec(dllexport) int HttpPost(const char* url, const char* headers, const char* body, char* response, int responseSize);

// HTTP POST 函数实现
extern "C" __declspec(dllexport) int HttpPost(const char* url, const char* headers, const char* body, char* response, int responseSize) {
    WriteLog("HttpPost called with parameters:");
    WriteLog("URL: " + std::string(url));
    WriteLog("Headers: " + std::string(headers));
    WriteLog("Body: " + std::string(body));

    if (!url || strlen(url) == 0) {
        WriteLog("Error: URL is empty or null!");
        return -1;
    }

    // 转换 URL 和 Headers 为宽字符
    std::wstring wideUrl = ConvertToWideString(url);
    std::wstring wideHeaders = ConvertToWideString(headers);
    std::string utf8Body = body; // Body 应该是 UTF-8 格式，不需要转换

    if (wideUrl.find(L"http://") != 0 && wideUrl.find(L"https://") != 0) {
        WriteLog("Error: URL must start with http:// or https://");
        return -1;
    }

    // 打开 Internet 会话
    HINTERNET hInternet = InternetOpenW(L"MT4_HTTP_Client", INTERNET_OPEN_TYPE_DIRECT, NULL, NULL, 0);
    if (!hInternet) {
        WriteLog("Error: InternetOpenW failed! Error code: " + std::to_string(GetLastError()));
        return -1;
    }

    // 解析 URL
    URL_COMPONENTSW urlComponents = {0};
    wchar_t scheme[16] = {0};
    wchar_t hostName[256] = {0};
    wchar_t urlPath[1024] = {0};
    wchar_t extraInfo[256] = {0};

    urlComponents.dwStructSize = sizeof(urlComponents);
    urlComponents.lpszScheme = scheme;
    urlComponents.dwSchemeLength = sizeof(scheme) / sizeof(wchar_t);
    urlComponents.lpszHostName = hostName;
    urlComponents.dwHostNameLength = sizeof(hostName) / sizeof(wchar_t);
    urlComponents.lpszUrlPath = urlPath;
    urlComponents.dwUrlPathLength = sizeof(urlPath) / sizeof(wchar_t);
    urlComponents.lpszExtraInfo = extraInfo;
    urlComponents.dwExtraInfoLength = sizeof(extraInfo) / sizeof(wchar_t);

    if (!InternetCrackUrlW(wideUrl.c_str(), 0, 0, &urlComponents)) {
        WriteLog("Error: InternetCrackUrlW failed! URL: " + ConvertToUTF8(wideUrl.c_str()) + ", Error code: " + std::to_string(GetLastError()));
        InternetCloseHandle(hInternet);
        return -2;
    }

    WriteLog("InternetCrackUrlW succeeded!");
    WriteLog("Scheme: " + ConvertToUTF8(urlComponents.lpszScheme ? urlComponents.lpszScheme : L"NULL"));
    WriteLog("HostName: " + ConvertToUTF8(urlComponents.lpszHostName ? urlComponents.lpszHostName : L"NULL"));
    WriteLog("UrlPath: " + ConvertToUTF8(urlComponents.lpszUrlPath ? urlComponents.lpszUrlPath : L"NULL"));
    WriteLog("Port: " + std::to_string(urlComponents.nPort));

    // 创建连接
    HINTERNET hConnect = InternetConnectW(hInternet, urlComponents.lpszHostName, urlComponents.nPort, NULL, NULL, INTERNET_SERVICE_HTTP, 0, 0);
    if (!hConnect) {
        WriteLog("Error: InternetConnectW failed! Error code: " + std::to_string(GetLastError()));
        InternetCloseHandle(hInternet);
        return -3;
    }

    // 打开 POST 请求
    HINTERNET hRequest = HttpOpenRequestW(hConnect, L"POST", urlComponents.lpszUrlPath, NULL, NULL, NULL, INTERNET_FLAG_RELOAD | INTERNET_FLAG_NO_CACHE_WRITE, 0);
    if (!hRequest) {
        WriteLog("Error: HttpOpenRequestW failed! Error code: " + std::to_string(GetLastError()));
        InternetCloseHandle(hConnect);
        InternetCloseHandle(hInternet);
        return -4;
    }

    // 构造请求头
    std::wstring fixedHeaders = L"Content-Type: application/json\\r\\n";
    fixedHeaders += L"Host: 127.0.0.1\\r\\n";
    fixedHeaders += L"Accept: application/json\\r\\n";
    fixedHeaders += L"User-Agent: MT4_HTTP_Client\\r\\n";
    fixedHeaders += L"Content-Length: " + ToWString(utf8Body.size()) + L"\\r\\n\\r\\n"; // 额外的空行表示请求头结束

    WriteLog("Final Headers (Wide): " + ConvertToUTF8(fixedHeaders.c_str()));
    WriteLog("Request Body: " + utf8Body);

    // 发送请求
    BOOL result = HttpSendRequestW(hRequest, fixedHeaders.c_str(), fixedHeaders.size(), (LPVOID)utf8Body.c_str(), utf8Body.size());
    if (!result) {
        DWORD errorCode = GetLastError();
        WriteLog("Error: HttpSendRequestW failed! Error code: " + std::to_string(errorCode));

        InternetCloseHandle(hRequest);
        InternetCloseHandle(hConnect);
        InternetCloseHandle(hInternet);
        return -5;
    }

    // 读取响应
    char buffer[8192] = {0};
    DWORD bytesRead = 0;
    result = InternetReadFile(hRequest, buffer, sizeof(buffer) - 1, &bytesRead);
    if (!result) {
        WriteLog("Error: InternetReadFile failed! Error code: " + std::to_string(GetLastError()));
        InternetCloseHandle(hRequest);
        InternetCloseHandle(hConnect);
        InternetCloseHandle(hInternet);
        return -6;
    }

    buffer[bytesRead] = '\\0';

    // 将响应写入输出缓冲区
    strncpy(response, buffer, responseSize - 1);
    response[responseSize - 1] = '\\0';

    WriteLog("Response: " + std::string(buffer));

    InternetCloseHandle(hRequest);
    InternetCloseHandle(hConnect);
    InternetCloseHandle(hInternet);

    return 0;
}

这个代码实现了一个使用 Windows API 的 HTTP POST 请求函数，并包含了日志记录和字符串编码转换功能。以下是对代码中所有知识点的详细解读：

1. Windows API 基础知识

Windows API 是微软提供的一组函数，用于开发 Windows 应用程序。本代码中使用了以下 Windows API：

这些函数的名称以 W 结尾，表示它们使用宽字符（UTF-16编码）。

2. 字符编码转换

本代码实现了从 UTF-8 到 UTF-16 和从 UTF-16 到 UTF-8 的转换功能。Windows API 中通常使用宽字符（UTF-16），而 HTTP 请求中的数据通常是 UTF-8，因此需要进行编码转换。

UTF-8 转 UTF-16

std::wstring ConvertToWideString(const char* utf8String) {
    int wideLength = MultiByteToWideChar(CP_UTF8, 0, utf8String, -1, NULL, 0);
    std::wstring wideString(wideLength, 0);
    MultiByteToWideChar(CP_UTF8, 0, utf8String, -1, &wideString[0], wideLength);
    return wideString;
}

UTF-16 转 UTF-8

std::string ConvertToUTF8(const wchar_t* wideString) {
    int utf8Length = WideCharToMultiByte(CP_UTF8, 0, wideString, -1, NULL, 0, NULL, NULL);
    std::string utf8String(utf8Length, 0);
    WideCharToMultiByte(CP_UTF8, 0, wideString, -1, &utf8String[0], utf8Length, NULL, NULL);
    return utf8String;
}

3. 文件操作

日志写入

void WriteLog(const std::string& message) {
    const wchar_t* logFileName = L"chriszhao_Debug.log";

    HANDLE hFile = CreateFileW(
        logFileName,
        FILE_APPEND_DATA,
        FILE_SHARE_READ,
        NULL,
        OPEN_ALWAYS,
        FILE_ATTRIBUTE_NORMAL,
        NULL
    );

    if (hFile == INVALID_HANDLE_VALUE) {
        std::cerr << "Failed to open log file: " << ConvertToUTF8(logFileName) << std::endl;
        return;
    }

    DWORD bytesWritten = 0;
    WriteFile(hFile, message.c_str(), message.size(), &bytesWritten, NULL);
    WriteFile(hFile, "\\n", 1, &bytesWritten, NULL);
    CloseHandle(hFile);
}

日志记录功能将调试信息写入到 chriszhao_Debug.log 文件，方便调试和问题排查。

4. HTTP 请求处理

该代码实现了一个 HTTP POST 请求，涉及以下步骤：

4.1 初始化 Internet 会话

HINTERNET hInternet = InternetOpenW(L"MT4_HTTP_Client", INTERNET_OPEN_TYPE_DIRECT, NULL, NULL, 0);

4.2 解析 URL

URL_COMPONENTSW urlComponents = {0};
if (!InternetCrackUrlW(wideUrl.c_str(), 0, 0, &urlComponents)) {
    WriteLog("Error: InternetCrackUrlW failed! Error code: " + std::to_string(GetLastError()));
    InternetCloseHandle(hInternet);
    return -2;
}

4.3 创建连接

HINTERNET hConnect = InternetConnectW(hInternet, urlComponents.lpszHostName, urlComponents.nPort, NULL, NULL, INTERNET_SERVICE_HTTP, 0, 0);

4.4 创建 HTTP 请求

HINTERNET hRequest = HttpOpenRequestW(hConnect, L"POST", urlComponents.lpszUrlPath, NULL, NULL, NULL, INTERNET_FLAG_RELOAD | INTERNET_FLAG_NO_CACHE_WRITE, 0);

4.5 发送 HTTP 请求

BOOL result = HttpSendRequestW(hRequest, fixedHeaders.c_str(), fixedHeaders.size(), (LPVOID)utf8Body.c_str(), utf8Body.size());

4.6 读取响应

result = InternetReadFile(hRequest, buffer, sizeof(buffer) - 1, &bytesRead);

5. 错误处理

代码中大量使用了 GetLastError 来获取错误码，并记录到日志中。例如：

WriteLog("Error: InternetOpenW failed! Error code: " + std::to_string(GetLastError()));

6. 导出函数

代码使用了 __declspec(dllexport) 关键字导出函数，使得它可以被其他程序调用：

extern "C" __declspec(dllexport) int HttpPost(const char* url, const char* headers, const char* body, char* response, int responseSize);

总结

这段代码展示了如何使用 Windows API 实现文件操作、字符串编码转换、HTTP 请求处理等功能。主要知识点包括：

  1. Windows API 的使用。
  2. 字符编码转换（UTF-8 和 UTF-16）。
  3. 文件操作和日志记录。
  4. HTTP 请求的创建、发送和响应处理。
  5. 错误处理和调试。
  6. 导出函数供外部使用。

它是一个完整的 HTTP 客户端实现，适合学习 Windows API 和网络编程的开发者。

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