Question

如何使用Java在城市中生成随机位置（经度和纬度）？

我想测试一个城市内的随机位置（目前只有一个城市）的应用功能。

Answer 1

您可能想要使用Google地图＆＃34;反向地理编码＆＃34;帮助查看一个随机位置是否在一个城市内。

考虑以下部分代码演示：

TestRandomCityLocations Main

package com.example.mapping;

import java.util.Random;

public class TestRandomCityLocation {
    // Class fields
    private static TestRandomCityLocation me;
    private static final String[] defaultArguments = { "" };

    // Object fields

    public static void main(String[] args) {
        String[] arguments;

        me = new TestRandomCityLocation();
        if (args == null || args.length == 0) {
            arguments = defaultArguments;
        } else {
            arguments = args;
        }

        me.doWork(arguments);

    }

    private void doWork(String[] arguments) {
        int maximumPoints = 100;
        GeographicPoint newLocation;

        GeographicSquare mockCityGeo = new GeographicSquare(
                new GeographicPoint(38.7, -77.0), new GeographicPoint(38.9,
                        -76.9));
        String cityName = "Google Maps city name";

        Random randomGenerator = new Random();

        double deltaLong = mockCityGeo.getDeltaLongitude();
        double deltaLat = mockCityGeo.getDeltaLatitude();

        for (int i = 0; i < maximumPoints; i++) {
            newLocation = new GeographicPoint(
                    mockCityGeo.getLowerLeftLatitude() + deltaLat
                            * randomGenerator.nextDouble(),
                    mockCityGeo.getLowerLeftLongitude() + deltaLong
                            * randomGenerator.nextDouble());

            // TODO test to see of newLocation is in the city
            if (GoogleMapInfo.isWithinCity(cityName, newLocation)) {
                // TODO Do something
            }

        }
    }

}

GeographicSquare类

package com.example.mapping;

public class GeographicSquare {
    // Object fields
    private GeographicPoint lowerLeft;
    private GeographicPoint upperRight;
    public GeographicSquare (GeographicPoint lowerLeft, GeographicPoint upperRight) {
        this.lowerLeft = lowerLeft;
        this.upperRight = upperRight;
    }
    public double getDeltaLongitude() {
        return lowerLeft.getLongitudeDifference(upperRight);
    }
    public double getDeltaLatitude() {
        return lowerLeft.getLatitudeDifference(upperRight);
    }
    public double getLowerLeftLongitude() {
        return lowerLeft.getLongitude();
    }
    public double getLowerLeftLatitude() {
        return lowerLeft.getLatitude();
    }
}

GeographicPoint类

package com.example.mapping;

public class GeographicPoint {
    // Object fields
    private double latitude; 
    private double longitude;

    public GeographicPoint(double latitudeDegrees, double  longitudeDegrees) {
        this.latitude = latitudeDegrees;
        this.longitude = longitudeDegrees;
    }

    public double getLatitude() {
        return latitude;
    }

    public double getLongitude() {
        return longitude;
    }

    /** Distance calculation using Haversine formula to calculate a great-circle distance 
     * between two points of the surface of the earth.
     * 
     * formula: a = sin²(Δφ/2) + cos φ1 ⋅ cos φ2 ⋅ sin²(Δλ/2)
     * c = 2 ⋅ atan2( √a, √(1−a) )
     * d = R ⋅ c
        where   φ is latitude, λ is longitude, R is earth’s radius 
        (mean radius = 3958,756 miles (6,371km));
        Note bene: angles must be in radians to pass to trig functions!
     * @param location
     * @return
     */
    public double milesFrom(GeographicPoint location) {

        double rInMiles = 3958.756;
        double lat1Radians = radiansFromDegrees(latitude);
        double lat2Radians = radiansFromDegrees(location.getLatitude());
        double deltaLat = radiansFromDegrees(location.getLatitude()-latitude);
        double deltaLong = radiansFromDegrees(location.getLongitude()-longitude);

        double a = Math.sin(deltaLat/2.0) * Math.sin(deltaLat/2.0) +
                   Math.cos(lat1Radians) * Math.cos(lat2Radians) * Math.sin(deltaLong/2.0)*Math.sin(deltaLong/2.0);
        double c = 2.0 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
        double d = rInMiles * c;

        return d;

    }

    public double getLatitudeDifference(GeographicPoint location) {
        return Math.abs(latitude - location.getLatitude());
    }
    public double getLongitudeDifference(GeographicPoint location) {
        return Math.abs(longitude - location.getLongitude());
    }
    public GeographicPoint getOffsetPoint(double latitudeOffset, double longitudeOffset) {
        return new GeographicPoint(latitude+latitudeOffset, longitude+longitudeOffset);
    }
    // Internal methods

    private double radiansFromDegrees(double degrees) {
        return (degrees * Math.PI) / 180.0;
    }
}

模拟GoogleMapInfo类

package com.example.mapping;

public class GoogleMapInfo {
    // Consider using Reverse Geocoding in Google Maps api and look at locality political
    // see: [https://developers.google.com/maps/documentation/geocoding/#ReverseGeocoding][1] 


    public static boolean isWithinCity(String cityName,
            GeographicPoint newLocation) {
        // Get governmental info for location and see if the city name matches
        return true;
    }
}

如何使用java在城市中生成随机经度和纬度？

1 个答案: