C++ CPR：现代化、易用的HTTP客户端库

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摘要： C++ CPR：现代化、易用的HTTP客户端库项目概述 C++ CPR（C++ Requests）是一个受Python Requests库启发的现代化C++ HTTP客户端库。它...

C++ CPR：现代化、易用的HTTP客户端库

项目概述

C++ CPR（C++ Requests）是一个受Python Requests库启发的现代化C++ HTTP客户端库。它提供了简洁直观的API，让C++开发者能够轻松地进行HTTP通信，无需处理底层复杂的网络细节。

主要特性

1. 简洁直观的API

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#include <cpr/cpr.h>

// 简单的GET请求
auto response = cpr::Get(cpr::Url{"https://api.example.com/data"});
std::cout << "Status: " << response.status_code << std::endl;
std::cout << "Body: " << response.text << std::endl;

2. 完整的HTTP方法支持

GET、POST、PUT、DELETE、PATCH、HEAD、OPTIONS

3. 丰富的功能

URL参数
请求头设置
请求体（JSON、表单数据、文件上传）
Cookie管理
超时设置
代理支持
认证（Basic、Digest、Bearer Token）
异步请求
重定向控制

安装与配置

使用vcpkg安装

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vcpkg install cpr

使用CMake集成

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find_package(cpr REQUIRED)
target_link_libraries(your_target PRIVATE cpr::cpr)

实用示例

1. 基本GET请求

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#include <iostream>
#include <cpr/cpr.h>

int main() {
    // 带参数的GET请求
    auto response = cpr::Get(
        cpr::Url{"https://httpbin.org/get"},
        cpr::Parameters{{"key1", "value1"}, {"key2", "value2"}}
    );
    
    if (response.status_code == 200) {
        std::cout << "Response: " << response.text << std::endl;
    } else {
        std::cout << "Request failed: " << response.error.message << std::endl;
    }
    
    return 0;
}

2. POST请求（JSON数据）

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#include <iostream>
#include <cpr/cpr.h>
#include <nlohmann/json.hpp>

int main() {
    // 创建JSON数据
    nlohmann::json data = {
        {"name", "John Doe"},
        {"email", "john@example.com"},
        {"age", 30}
    };
    
    // 发送POST请求
    auto response = cpr::Post(
        cpr::Url{"https://httpbin.org/post"},
        cpr::Header{{"Content-Type", "application/json"}},
        cpr::Body{data.dump()}
    );
    
    std::cout << "Status: " << response.status_code << std::endl;
    std::cout << "Response: " << response.text << std::endl;
    
    return 0;
}

3. 文件上传

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#include <iostream>
#include <cpr/cpr.h>

int main() {
    // 上传文件
    auto response = cpr::Post(
        cpr::Url{"https://httpbin.org/post"},
        cpr::Multipart{
            {"file", cpr::File{"path/to/file.txt"}},
            {"description", "This is a test file"}
        }
    );
    
    std::cout << "Upload status: " << response.status_code << std::endl;
    
    return 0;
}

4. 带认证的请求

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#include <iostream>
#include <cpr/cpr.h>

int main() {
    // Basic认证
    auto response = cpr::Get(
        cpr::Url{"https://httpbin.org/basic-auth/user/pass"},
        cpr::Authentication{"user", "pass", cpr::AuthMode::BASIC}
    );
    
    // Bearer Token认证
    auto token_response = cpr::Get(
        cpr::Url{"https://api.example.com/protected"},
        cpr::Bearer{"your_token_here"}
    );
    
    return 0;
}

5. 异步请求

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#include <iostream>
#include <cpr/cpr.h>
#include <future>

int main() {
    // 发起异步请求
    std::future<cpr::Response> future = cpr::GetAsync(
        cpr::Url{"https://httpbin.org/delay/3"}
    );
    
    std::cout << "Request sent, doing other work..." << std::endl;
    
    // 等待响应
    cpr::Response response = future.get();
    
    std::cout << "Async response received: " << response.status_code << std::endl;
    
    return 0;
}

6. 自定义超时和重试

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#include <iostream>
#include <cpr/cpr.h>

int main() {
    // 设置超时和重试策略
    auto response = cpr::Get(
        cpr::Url{"https://httpbin.org/delay/5"},
        cpr::Timeout{3000},  // 3秒超时
        cpr::ConnectTimeout{2000},  // 连接超时2秒
        cpr::LowSpeed{100, 10}  // 10秒内下载速度低于100字节则超时
    );
    
    if (response.status_code == 0) {
        std::cout << "Request timed out or failed" << std::endl;
    }
    
    return 0;
}

错误处理

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#include <iostream>
#include <cpr/cpr.h>

int main() {
    try {
        auto response = cpr::Get(cpr::Url{"https://invalid-url.example"});
        
        if (response.error) {
            std::cerr << "Error: " << response.error.message << std::endl;
            std::cerr << "Error code: " << response.error.code << std::endl;
        }
        
        if (response.status_code >= 400) {
            std::cerr << "HTTP error: " << response.status_code << std::endl;
        }
        
    } catch (const std::exception& e) {
        std::cerr << "Exception: " << e.what() << std::endl;
    }
    
    return 0;
}