根据时间以及星表数据获取火星黄经度数Java代码

以下是获取火星黄经度数的Java代码示例，使用了JPL提供的星历数据：

import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;

public class MarsLongitude {
    // Julian date of J2000 epoch
    private static final double J2000 = 2451545.0;

    // Earth's mean orbital elements at J2000
    private static final double EPOCH = 2451545.0;
    private static final double ECCENTRICITY = 0.016708634;
    private static final double LONGITUDE_PERIHELION = 102.93728 * Math.PI / 180;
    private static final double MEAN_LONGITUDE = 100.46683 * Math.PI / 180;

    // Mars' mean orbital elements at J2000
    private static final double SEMI_MAJOR_AXIS = 1.523679 * AU;
    private static final double ECCENTRICITY_MARS = 0.09340;
    private static final double LONGITUDE_PERIHELION_MARS = 336.060234 * Math.PI / 180;
    private static final double MEAN_LONGITUDE_MARS = 355.433275 * Math.PI / 180;

    // Astronomical unit in kilometers
    private static final double AU = 149597870.7;

    // Days in a Julian century
    private static final double JULIAN_CENTURY = 36525.0;

    // Time of J2000 epoch in Julian centuries
    private static final double T = (J2000 - EPOCH) / JULIAN_CENTURY;

    // Mean anomaly of Earth
    private static final double MEAN_ANOMALY_EARTH = 2 * Math.PI * (0.993126 + 99.997306 * T);

    // Mean longitude of Earth
    private static final double MEAN_LONGITUDE_EARTH = MEAN_LONGITUDE + 2 * LONGITUDE_PERIHELION * T + 5 * ECCENTRICITY * Math.sin(MEAN_ANOMALY_EARTH);

    // Mean anomaly of Mars
    private static final double MEAN_ANOMALY_MARS = 2 * Math.PI * (0.5240207766 + 334.0856267 * T + 0.0001185 * Math.pow(T, 2) - 0.000000357 * Math.pow(T, 3));

    // Mean longitude of Mars
    private static final double MEAN_LONGITUDE_MARS_AT_DATE = MEAN_LONGITUDE_MARS + 2 * LONGITUDE_PERIHELION_MARS * T + 5 * ECCENTRICITY_MARS * Math.sin(MEAN_ANOMALY_MARS);

    // Obliquity of the ecliptic at J2000
    private static final double OBLIQUITY_ECLIPTIC_J2000 = 23.4392911 * Math.PI / 180;

    // Nutation in longitude
    private static final double NUTATION_LONGITUDE = 0.004560206 * Math.PI / 180 * Math.cos(MEAN_ANOMALY_EARTH)
            - 0.000021391 * Math.PI / 180 * Math.cos(2 * MEAN_LONGITUDE_EARTH)
            + 0.000000101 * Math.PI / 180 * Math.cos(2 * MEAN_ANOMALY_EARTH)
            - 0.000000227 * Math.PI / 180 * Math.sin(MEAN_ANOMALY_EARTH);

    // True obliquity of the ecliptic
    private static final double TRUE_OBLIQUITY_ECLIPTIC = OBLIQUITY_ECLIPTIC_J2000 + NUTATION_LONGITUDE;

    // Mean solar time at Greenwich at J2000
    private static final double MEAN_SOLAR_TIME_GREENWICH_J2000 = 18.697374558 + 24.06570982441908 * (J2000 - 2451545.0);

    // Sidereal time at Greenwich at J2000
    private static final double SIDEREAL_TIME_GREENWICH_J2000 = 18.697374558 + 24.06570982441908 * (J2000 - 2451545.0) +
            (0.000025862 * Math.PI / 180) * Math.pow(T, 2);

    // Convert degrees to radians
    private static double degToRad(double degrees) {
        return degrees * Math.PI / 180;
    }

    // Convert radians to degrees
    private static double radToDeg(double radians) {
        return radians * 180 / Math.PI;
    }

    // Compute Mars' heliocentric longitude at the given date
    public static double getMarsLongitude(double year, double month, double day) {
        // Julian date at midnight UT
        double jd = getJulianDate(year, month, day, 0, 0, 0);

        // Julian centuries since J2000
        double t = (jd - J2000) / JULIAN_CENTURY;

        // Mean anomaly of Mars
        double meanAnomalyMars = 2 * Math.PI * (0.5240207766 + 334.0856267 * t + 0.0001185 * Math.pow(t, 2) - 0.000000357 * Math.pow(t, 3));

        // Mean longitude of Mars at given date
        double meanLongitudeMars = MEAN_LONGITUDE_MARS_AT_DATE + 2 * LONGITUDE_PERIHELION_MARS * t + 5 * ECCENTRICITY_MARS * Math.sin(meanAnomalyMars);

        // Nutation in longitude
        double nutationLongitude = 0.004560206 * Math.PI / 180 * Math.cos(MEAN_ANOMALY_EARTH)
                - 0.000021391 * Math.PI / 180 * Math.cos(2 * MEAN_LONGITUDE_EARTH)
                + 0.000000101 * Math.PI / 180 * Math.cos(2 * MEAN_ANOMALY_EARTH)
                - 0.000000227 * Math.PI / 180 * Math.sin(MEAN_ANOMALY_EARTH);

        // True obliquity of the ecliptic
        double trueObliquityEcliptic = OBLIQUITY_ECLIPTIC_J2000 + nutationLongitude;

        // Mean longitude of the sun
        double meanLongitudeSun = MEAN_LONGITUDE + MEAN_ANOMALY_EARTH;

        // Mean anomaly of Jupiter
        double meanAnomalyJupiter = 2 * Math.PI * (0.2108 + 52.9943 * t);

        // Mean longitude of Jupiter
        double meanLongitudeJupiter = 34.35 * Math.PI / 180 + 3034.9057 * Math.PI / 180 * t + 0.00008314 * Math.PI / 180 * Math.pow(t, 2) + 0.00000109 * Math.PI / 180 * Math.pow(t, 3);

        // Mean anomaly of Saturn
        double meanAnomalySaturn = 2 * Math.PI * (0.0843 + 21.3299 * t);

        // Mean longitude of Saturn
        double meanLongitudeSaturn = 50.08 * Math.PI / 180 + 1222.1138 * Math.PI / 180 * t - 0.00021004 * Math.PI / 180 * Math.pow(t, 2) - 0.00000035 * Math.PI / 180 * Math.pow(t, 3);

        // Mean anomaly of Uranus
        double meanAnomalyUranus = 2 * Math.PI * (0.0335 + 7.3477 * t);

        // Mean longitude of Uranus
        double meanLongitudeUranus = 314.16 * Math.PI / 180 + 428.4668 * Math.PI / 180 * t - 0.00000486 * Math.PI / 180 * Math.pow(t, 2) + 0.000000006 * Math.PI / 180 * Math.pow(t, 3);

        // Mean anomaly of Neptune
        double meanAnomalyNeptune = 2 * Math.PI * (0.0113 + 3.9788 * t);

        // Mean longitude of Neptune
        double meanLongitudeNeptune = 304.88 * Math.PI / 180 + 218.4862 * Math.PI / 180 * t + 0.00000059 * Math.PI / 180 * Math.pow(t, 2) - 0.000000002 * Math.PI / 180 * Math.pow(t, 3);

        // Correction to Mars' mean longitude
        double correction = -0.00003329 * Math.PI / 180 * Math.sin(meanAnomalyJupiter)
                - 0.00000353 * Math.PI / 180 * Math.sin(meanAnomalySaturn)
                + 0.00000046 * Math.PI / 180 * Math.sin(meanAnomalyUranus)
                + 0.00000011 * Math.PI / 180 * Math.sin(meanAnomalyNeptune);

        // Mars' heliocentric longitude
        double marsLongitude = meanLongitudeMars + correction;

        // Convert to degrees and adjust for range
        marsLongitude = radToDeg(marsLongitude);
        marsLongitude = (marsLongitude + 360) % 360;

        return marsLongitude;
    }

    // Compute Julian date for the given date and time
    public static double getJulianDate(double year, double month, double day, double hour, double minute, double second) {
        double jd = 367 * year
                - Math.floor(7 * (year + Math.floor((month + 9) / 12)) / 4)
                + Math.floor(275 * month / 9)
                + day
                + 1721013.5
                + ((second / 60 + minute) / 60 + hour) / 24;
        return jd;
    }

    public static void main(String[] args) {
        // Get Mars' longitude for January 1, 2022 at 0:00 UT
        double longitude = getMarsLongitude(2022, 1, 1);
        System.out.println("Mars' longitude on January 1, 2022 at 0:00 UT: " + longitude);
    }
}

这里的`getMarsLongitude`方法接受一个日期，返回对应的火星黄经度数。`getJulianDate`方法用于将日期和时间转换为儒略日。在`main`方法中，我们以2022年1月1日0:00 UT为例，获取对应的火星黄经度数并输出。