【C++进阶实战】基于linux的天气预报系统

项目结构

main.cpp：主程序文件，负责用户交互和调用天气查询函数。
weather_api.cpp：实现天气数据的获取和解析。
weather_api.h：天气数据获取和解析的头文件。
CMakeLists.txt：CMake配置文件，用于编译项目。

1. 安装依赖库

首先，你需要安装cURL库。在大多数Linux发行版中，你可以使用包管理器来安装：

sudo apt-get install libcurl4-openssl-dev

在Windows上，你可以从cURL官方网站下载预编译的库文件。

2. 获取API密钥

注册并获取OpenWeatherMap API密钥。你可以在这里注册：OpenWeatherMap API

3. 项目文件

weather_api.h

#ifndef WEATHER_API_H
#define WEATHER_API_H

#include <string>
#include <curl/curl.h>

class WeatherAPI {
public:
    WeatherAPI(const std::string& apiKey);
    std::string getWeather(const std::string& city);

private:
    std::string apiKey;
};

#endif // WEATHER_API_H

weather_api.cpp

#include "weather_api.h"
#include <iostream>
#include <string>
#include <curl/curl.h>
#include <nlohmann/json.hpp>

using json = nlohmann::json;

size_t WriteCallback(void* contents, size_t size, size_t nmemb, std::string* buffer) {
    size_t totalSize = size * nmemb;
    buffer->append((char*)contents, totalSize);
    return totalSize;
}

WeatherAPI::WeatherAPI(const std::string& apiKey) : apiKey(apiKey) {}

std::string WeatherAPI::getWeather(const std::string& city) {
    CURL* curl;
    CURLcode res;
    std::string readBuffer;

    curl_global_init(CURL_GLOBAL_DEFAULT);
    curl = curl_easy_init();

    if (curl) {
        std::string url = "http://api.openweathermap.org/data/2.5/weather?q=" + city + "&appid=" + apiKey + "&units=metric";
        curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WriteCallback);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, &readBuffer);
        res = curl_easy_perform(curl);

        if (res != CURLE_OK) {
            std::cerr << "curl_easy_perform() failed: " << curl_easy_strerror(res) << std::endl;
        }

        curl_easy_cleanup(curl);
    }

    curl_global_cleanup();

    return readBuffer;
}

main.cpp

#include <iostream>
#include <string>
#include "weather_api.h"
#include <nlohmann/json.hpp>

using json = nlohmann::json;

void displayWeather(const std::string& response) {
    try {
        json j = json::parse(response);
        std::string city = j["name"];
        std::string country = j["sys"]["country"];
        double temperature = j["main"]["temp"];
        std::string description = j["weather"][0]["description"];
        double humidity = j["main"]["humidity"];
        double windSpeed = j["wind"]["speed"];

        std::cout << "Weather in " << city << ", " << country << ":" << std::endl;
        std::cout << "Temperature: " << temperature << " °C" << std::endl;
        std::cout << "Description: " << description << std::endl;
        std::cout << "Humidity: " << humidity << "%" << std::endl;
        std::cout << "Wind Speed: " << windSpeed << " m/s" << std::endl;
    } catch (const std::exception& e) {
        std::cerr << "Error parsing JSON: " << e.what() << std::endl;
    }
}

int main() {
    std::string apiKey = "YOUR_API_KEY_HERE"; // 替换为你的API密钥
    WeatherAPI api(apiKey);

    std::string city;
    std::cout << "Enter the city name: ";
    std::getline(std::cin, city);

    std::string response = api.getWeather(city);
    displayWeather(response);

    return 0;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.10)
project(SimpleWeatherApp)

set(CMAKE_CXX_STANDARD 17)

find_package(CURL REQUIRED)
include_directories(${CURL_INCLUDE_DIRS})

add_executable(SimpleWeatherApp main.cpp weather_api.cpp)

target_link_libraries(SimpleWeatherApp ${CURL_LIBRARIES})

4. 编译和运行

创建一个项目目录并导航到该目录。
创建上述文件并保存。
在项目目录中创建一个build目录并进入该目录：
```
mkdir build
cd build
```
运行CMake生成Makefile：
```
cmake ..
```
编译项目：
```
make
```
运行程序：
```
./SimpleWeatherApp
```

5. 运行示例

运行程序后，输入一个城市名，程序将显示该城市的天气信息。

注意事项

确保你的API密钥是有效的。
如果你在编译过程中遇到问题，检查是否正确安装了所有依赖库。
你可以根据需要扩展功能，例如添加更多的天气信息显示、错误处理等。