I have a long list of towns and cities, and I'd like to add latitude and longitude information to each of them.
Does anyone know the easiest way to generate this information once?
See also Geocode multiple addresses
The first part of the third video shows how to get latitude and Longitude using Google Refine and geocoding. No need to write a new script. Ideal for doing this kind of change once.
Or use www.geonames.org - there's language APIs for that. Or Open Street Map's Nominatim: http://wiki.openstreetmap.org/wiki/Nominatim - google have slightly more restrictive terms of service.
You can use the Google Geocoding API. Check the API at this URL: http://code.google.com/apis/maps/documentation/geocoding/
What follows next is writing some code. I am doing something similar in C# and it is quite easy here.
Most geocoding services can handle queries with only administrative names which is what you're after, e.g., municipality and region. So I'd choose one you like that also handles batch or bulk requests, e.g., the Bing Spatial Data API (here's an article on batch geocoding with it.)
An alternative approach that might be useful if you're on a budget and have a lot of these to do would be to download the Geonames database and write a bit of code to import it into your database or index it; then query it however and how often you like, e.g., if you put your places in another table you could SELECT [...] FROM my_places LEFT JOIN geonames [...]. I used to import Geonames DB into a vanilla PostgreSQL nightly and probably still have the code in a git repo somewhere if that's a route you want to try (comment and I'll find it and attach.)
For a service that uses google, which I find most accurate. Look at http://www.torchproducts.com/tools/geocode
来源：https://stackoverflow.com/questions/5133927/finding-latitude-and-longitude-of-many-places-once