Java中单字段温度转换类的设计与实现

public class Temperature {
    // 内部私有字段，统一存储为开尔文
    private final double temperatureInKelvin;

    // 常用转换常量，提高可读性和维护性
    private static final double ABSOLUTE_ZERO_CELSIUS = 273.15; // 0 K = -273.15 C
    private static final double FAHRENHEIT_OFFSET = 32;
    private static final double FAHRENHEIT_SCALE_FACTOR = 9.0 / 5.0; // C to F
    private static final double CELSIUS_SCALE_FACTOR = 5.0 / 9.0; // F to C

    /**
     * 构造函数，根据给定的温度值和单位初始化Temperature对象。
     * 所有温度都会被转换为开尔文并存储。
     *
     * @param tm   温度值
     * @param unit 温度单位 ('C' for Celsius, 'F' for Fahrenheit, 'K' for Kelvin)
     * @throws IllegalArgumentException 如果单位无效
     */
    public Temperature(double tm, char unit) {
        double kelvinValue;
        switch (Character.toUpperCase(unit)) { // 统一处理大小写
            case 'C':
                kelvinValue = tm + ABSOLUTE_ZERO_CELSIUS;
                break;
            case 'F':
                kelvinValue = (tm - FAHRENHEIT_OFFSET) * CELSIUS_SCALE_FACTOR + ABSOLUTE_ZERO_CELSIUS;
                break;
            case 'K':
                kelvinValue = tm;
                break;
            default:
                throw new IllegalArgumentException("Unsupported temperature unit: " + unit + 
                                                   ". Only 'C', 'F', 'K' are allowed.");
        }
        this.temperatureInKelvin = kelvinValue;
    }

    /**
     * 获取以摄氏度表示的温度。
     * @return 摄氏度值
     */
    public double getInC() {
        return temperatureInKelvin - ABSOLUTE_ZERO_CELSIUS;
    }

    /**
     * 获取以华氏度表示的温度。
     * @return 华氏度值
     */
    public double getInF() {
        return (temperatureInKelvin - ABSOLUTE_ZERO_CELSIUS) * FAHRENHEIT_SCALE_FACTOR + FAHRENHEIT_OFFSET;
    }

    /**
     * 获取以开尔文表示的温度。
     * @return 开尔文值
     */
    public double getInK() {
        return temperatureInKelvin;
    }

    /**
     * 提供友好的字符串表示，方便调试和输出。
     * @return 温度的字符串表示，包含开尔文、摄氏度和华氏度。
     */
    @Override
    public String toString() {
        return String.format("%.2f K (%.2f °C, %.2f °F)", 
                             temperatureInKelvin, getInC(), getInF());
    }

    // 示例用法
    public static void main(String[] args) {
        Temperature tempC = new Temperature(25.0, 'C');
        System.out.println("25°C: " + tempC); // 自动调用toString()
        System.out.println("In Celsius: " + tempC.getInC() + " °C");
        System.out.println("In Fahrenheit: " + tempC.getInF() + " °F");
        System.out.println("In Kelvin: " + tempC.getInK() + " K");
        System.out.println("---");

        Temperature tempF = new Temperature(68.0, 'F');
        System.out.println("68°F: " + tempF);
        System.out.println("In Celsius: " + tempF.getInC() + " °C");
        System.out.println("In Fahrenheit: " + tempF.getInF() + " °F");
        System.out.println("In Kelvin: " + tempF.getInK() + " K");
        System.out.println("---");

        Temperature tempK = new Temperature(300.0, 'K');
        System.out.println("300K: " + tempK);
        System.out.println("In Celsius: " + tempK.getInC() + " °C");
        System.out.println("In Fahrenheit: " + tempK.getInF() + " °F");
        System.out.println("In Kelvin: " + tempK.getInK() + " K");
    }
}