使用Java程序查找具有指定半径的给定纬度（即位置）周围的纬度和纬度值

Question

All latitude and longitude values (including current location and other locations) are varchar datatype in mysql db table. I am struggling to get all maximum and minimum latitude/longitude values that are within 2km or 5km radius of current location. My current location latitude and longitude values and other location lat/long values are stored into mysql db table using google map api.

I need to fetch the location records (max/min latitude/longitude values)which are all within given radius of current location from table.

Input :

Location : AA (or) Lat: 12.561 and Lon : 77.48 Radius /Distance : 2km

Table :

Location | Lat | Long

AA | 12.561 | 77.48

A2 | 12.567 | 77.489

A4 | 12.59 | 78.42

A6 | 12.57 | 77.45

Output :

List of Location name which is satisfied above condition.

It would be great help, if you will give few line of java code.

I need to get the o/p of lat/long values all direction (N/E/S/W) without using bearing value as my application don't have bearing value. It should get output values only using input of current location latitude /longitude and distance/radius value.

Answer 1

You will need to change coordinates from Varchar to DECIMAL(8, 6) to allow to calculate distance.

The following SQL query uses Spherical Law of Cosines to calculate the distance between a coordinate and coordinates in a table.

d = acos( sin(φ1).sin(φ2) + cos(φ1).cos(φ2).cos(Δλ) ).R

The query uses MySQL Math functions

"SELECT Location,Lat,Long,(6367 * acos( cos( radians(center_lat) )
  * cos( radians( Lat ) ) * cos( radians( Long ) - radians(center_long) )
  + sin( radians(center_lat) ) * sin( radians( Lat ) ) ) ) AS distance FROM table 
  HAVING distance < radius ORDER BY distance ASC LIMIT 0 , 20"

Where center_lat & center_long are coordinates of given point

PS use 3956 for miles 6367 for kms