经纬度一个数字是多少米,经纬度1分相差多少米

它需要做以下两件事情：

1）在使用“附近的人”功能前提交自己的地理位置；

2）根据“我”的地理位置，计算出别人跟我的距离；

3）将第2步中计算出的距离由近及远，进行排序。

具体在产品技术上的实现原理和技术难点

1）现在移动端（ios、android等），通过系统的API很容易抓到用户当前的位置（即经纬度数据）；

2）根据第1步中的经纬度数据，很容易计算出两个点之间的距离

3）对第2步中的计算结果排序就更简单了。

技术难点

1）如何高效地进行两点距离的计算

2）如何高效地进行地理围栏的圈定

public class GeoHash { public static final double MINLAT = -90; public static final double MAXLAT = 90; public static final double MINLNG = -180; public static final double MAXLNG = 180; private static int numbits = 3 * 5; //经纬度单独编码长度 private static double minLat; private static double minLng; private final static char[] digits = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'j', 'k', 'm', 'n', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z' }; //定义编码映射关系 final static HashMap<Character, Integer> lookup = new HashMap<Character, Integer>(); //初始化编码映射内容 static { int i = 0; for (char c : digits) lookup.put(c, i ); } public GeoHash(){ setMinLatLng(); } public String encode(double lat, double lon) { BitSet latbits = getBits(lat, -90, 90); BitSet lonbits = getBits(lon, -180, 180); StringBuilder buffer = new StringBuilder(); for (int i = 0; i < numbits; i ) { buffer.append( (lonbits.get(i))?'1':'0'); buffer.append( (latbits.get(i))?'1':'0'); } String code = base32(Long.parseLong(buffer.toString(), 2)); //Log.i("okunu", "encode lat = " lat " lng = " lon " code = " code); return code; } public ArrayList<String> getArroundGeoHash(double lat, double lon){ //Log.i("okunu", "getArroundGeoHash lat = " lat " lng = " lon); ArrayList<String> list = new ArrayList<>(); double uplat = lat minLat; double downLat = lat - minLat; double leftlng = lon - minLng; double rightLng = lon minLng; String leftUp = encode(uplat, leftlng); list.add(leftUp); String leftMid = encode(lat, leftlng); list.add(leftMid); String leftDown = encode(downLat, leftlng); list.add(leftDown); String midUp = encode(uplat, lon); list.add(midUp); String midMid = encode(lat, lon); list.add(midMid); String midDown = encode(downLat, lon); list.add(midDown); String rightUp = encode(uplat, rightLng); list.add(rightUp); String rightMid = encode(lat, rightLng); list.add(rightMid); String rightDown = encode(downLat, rightLng); list.add(rightDown); //Log.i("okunu", "getArroundGeoHash list = " list.toString()); return list; } //根据经纬度和范围，获取对应的二进制 private BitSet getBits(double lat, double floor, double ceiling) { BitSet buffer = new BitSet(numbits); for (int i = 0; i < numbits; i ) { double mid = (floor ceiling) / 2; if (lat >= mid) { buffer.set(i); floor = mid; } else { ceiling = mid; } } return buffer; } //将经纬度合并后的二进制进行指定的32位编码 private String base32(long i) { char[] buf = new char[65]; int charPos = 64; boolean negative = (i < 0); if (!negative){ i = -i; } while (i <= -32) { buf[charPos--] = digits[(int) (-(i % 32))]; i /= 32; } buf[charPos] = digits[(int) (-i)]; if (negative){ buf[--charPos] = '-'; } return new String(buf, charPos, (65 - charPos)); } private void setMinLatLng() { minLat = MAXLAT - MINLAT; for (int i = 0; i < numbits; i ) { minLat /= 2.0; } minLng = MAXLNG - MINLNG; for (int i = 0; i < numbits; i ) { minLng /= 2.0; } } //根据二进制和范围解码 private double decode(BitSet bs, double floor, double ceiling) { double mid = 0; for (int i=0; i<bs.length(); i ) { mid = (floor ceiling) / 2; if (bs.get(i)) floor = mid; else ceiling = mid; } return mid; } //对编码后的字符串解码 public double[] decode(String geohash) { StringBuilder buffer = new StringBuilder(); for (char c : geohash.toCharArray()) { int i = lookup.get(c) 32; buffer.append( Integer.toString(i, 2).substring(1) ); } BitSet lonset = new BitSet(); BitSet latset = new BitSet(); //偶数位，经度 int j =0; for (int i=0; i< numbits*2;i =2) { boolean isSet = false; if ( i < buffer.length() ) isSet = buffer.charAt(i) == '1'; lonset.set(j , isSet); } //奇数位，纬度 j=0; for (int i=1; i< numbits*2;i =2) { boolean isSet = false; if ( i < buffer.length() ) isSet = buffer.charAt(i) == '1'; latset.set(j , isSet); } double lon = decode(lonset, -180, 180); double lat = decode(latset, -90, 90); return new double[] {lat, lon}; } public static void main(String[] args) throws Exception{ GeoHash geohash = new GeoHash(); // String s = geohash.encode(40.222012, 116.248283); // System.out.println(s); geohash.getArroundGeoHash(40.222012, 116.248283); // double[] geo = geohash.decode(s); // System.out.println(geo[0] " " geo[1]); } }

xxxxxxxxxxbr public class GeoHash {brpublic static final double MINLAT = -90;brpublic static final double MAXLAT = 90;brpublic static final double MINLNG = -180;brpublic static final double MAXLNG = 180;brbrprivate static int numbits = 3 * 5; //经纬度单独编码长度brbrprivate static double minLat;brprivate static double minLng;brbrprivate final static char[] digits = { '0', '1', '2', '3', '4', '5', '6', '7', '8',br '9', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'j', 'k', 'm', 'n', 'p',br 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z' };brbr//定义编码映射关系brfinal static HashMap<Character, Integer> lookup = new HashMap<Character, Integer>();br//初始化编码映射内容brstatic {br int i = 0;br for (char c : digits)br lookup.put(c, i );br}brbrpublic GeoHash(){br setMinLatLng();br}brbrpublic String encode(double lat, double lon) {br BitSet latbits = getBits(lat, -90, 90);br BitSet lonbits = getBits(lon, -180, 180);br StringBuilder buffer = new StringBuilder();br for (int i = 0; i < numbits; i ) {br buffer.append( (lonbits.get(i))?'1':'0');br buffer.append( (latbits.get(i))?'1':'0');br }br String code = base32(Long.parseLong(buffer.toString(), 2));br //Log.i("okunu", "encode lat = " lat " lng = " lon " code = " code);br return code;br}brbrpublic ArrayList<String> getArroundGeoHash(double lat, double lon){br //Log.i("okunu", "getArroundGeoHash lat = " lat " lng = " lon);br ArrayList<String> list = new ArrayList<>();br double uplat = lat minLat;br double downLat = lat - minLat;brbr double leftlng = lon - minLng;br double rightLng = lon minLng;brbr String leftUp = encode(uplat, leftlng);br list.add(leftUp);brbr String leftMid = encode(lat, leftlng);br list.add(leftMid);brbr String leftDown = encode(downLat, leftlng);br list.add(leftDown);brbr String midUp = encode(uplat, lon);br list.add(midUp);brbr String midMid = encode(lat, lon);br list.add(midMid);brbr String midDown = encode(downLat, lon);br list.add(midDown);brbr String rightUp = encode(uplat, rightLng);br list.add(rightUp);brbr String rightMid = encode(lat, rightLng);br list.add(rightMid);brbr String rightDown = encode(downLat, rightLng);br list.add(rightDown);brbr //Log.i("okunu", "getArroundGeoHash list = " list.toString());br return list;br}brbr//根据经纬度和范围，获取对应的二进制brprivate BitSet getBits(double lat, double floor, double ceiling) {br BitSet buffer = new BitSet(numbits);br for (int i = 0; i < numbits; i ) {br double mid = (floor ceiling) / 2;br if (lat >= mid) {br buffer.set(i);br floor = mid;br } else {br ceiling = mid;br }br }br return buffer;br}brbr//将经纬度合并后的二进制进行指定的32位编码brprivate String base32(long i) {br char[] buf = new char[65];br int charPos = 64;br boolean negative = (i < 0);br if (!negative){br i = -i;br }br while (i <= -32) {br buf[charPos--] = digits[(int) (-(i % 32))];br i /= 32;br }br buf[charPos] = digits[(int) (-i)];br if (negative){br buf[--charPos] = '-';br }br return new String(buf, charPos, (65 - charPos));br}brbrprivate void setMinLatLng() {br minLat = MAXLAT - MINLAT;br for (int i = 0; i < numbits; i ) {br minLat /= 2.0;br }br minLng = MAXLNG - MINLNG;br for (int i = 0; i < numbits; i ) {br minLng /= 2.0;br }br}brbr//根据二进制和范围解码brprivate double decode(BitSet bs, double floor, double ceiling) {br double mid = 0;br for (int i=0; i<bs.length(); i ) {br mid = (floor ceiling) / 2;br if (bs.get(i))br floor = mid;br elsebr ceiling = mid;br }br return mid;br}brbr//对编码后的字符串解码brpublic double[] decode(String geohash) {br StringBuilder buffer = new StringBuilder();br for (char c : geohash.toCharArray()) {br int i = lookup.get(c) 32;br buffer.append( Integer.toString(i, 2).substring(1) );br }brbr BitSet lonset = new BitSet();br BitSet latset = new BitSet();brbr //偶数位，经度br int j =0;br for (int i=0; i< numbits*2;i =2) {br boolean isSet = false;br if ( i < buffer.length() )br isSet = buffer.charAt(i) == '1';br lonset.set(j , isSet);br }brbr //奇数位，纬度br j=0;br for (int i=1; i< numbits*2;i =2) {br boolean isSet = false;br if ( i < buffer.length() )br isSet = buffer.charAt(i) == '1';br latset.set(j , isSet);br }brbr double lon = decode(lonset, -180, 180);br double lat = decode(latset, -90, 90);brbr return new double[] {lat, lon};br}brbrpublic static void main(String[] args) throws Exception{br GeoHash geohash = new GeoHash();br// String s = geohash.encode(40.222012, 116.248283);br// System.out.println(s);br geohash.getArroundGeoHash(40.222012, 116.248283);br// double[] geo = geohash.decode(s);br// System.out.println(geo[0] " " geo[1]);br}b核心算法获取任意两点距离

核心算法获取任意两点距离

/** * 计算地球上任意两点(经纬度)距离 * * @param long1 第一点经度 * @param lat1 第一点纬度 * @param long2 第二点经度 * @param lat2 第二点纬度 * @return 返回距离 单位：米 */ public static double Distance(double long1, double lat1, double long2, double lat2) { double a, b, R; R = 6378137; // 地球半径 lat1 = lat1 * Math.PI / 180.0; lat2 = lat2 * Math.PI / 180.0; a = lat1 - lat2; b = (long1 - long2) * Math.PI / 180.0; double d; double sa2, sb2; sa2 = Math.sin(a / 2.0); sb2 = Math.sin(b / 2.0); d = 2* R * Math.asin(Math.sqrt(sa2 * sa2 Math.cos(lat1) * Math.cos(lat2) * sb2 * sb2)); return d; }

xxxxxxxxxxbr/**brbr * 计算地球上任意两点(经纬度)距离 brbr * brbr * @param long1 第一点经度 brbr * @param lat1 第一点纬度 brbr * @param long2 第二点经度 brbr * @param lat2 第二点纬度 brbr * @return 返回距离 单位：米brbr */brbrpublic static double Distance(double long1, double lat1, double long2, double lat2)brbr{brbr double a, b, R;brbr R = 6378137; // 地球半径 brbr lat1 = lat1 * Math.PI / 180.0;brbr lat2 = lat2 * Math.PI / 180.0;brbr a = lat1 - lat2;brbr b = (long1 - long2) * Math.PI / 180.0;brbr double d;brbr double sa2, sb2;brbr sa2 = Math.sin(a / 2.0);brbr sb2 = Math.sin(b / 2.0);brbr d = 2* R * Math.asin(Math.sqrt(sa2 * sa2 Math.cos(lat1) * Math.cos(lat2) * sb2 * sb2));brbr return d;brbr}

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