如何在Google Elevation API中使用坐标数组？

Question

I am trying to send several locations in one request to Google Elevation API, you are supposed to be able to send up to 512 locations per request. Their documentation says to use: An array of coordinates separated using the pipe ('|') character: locations=40.714728,-73.998672|-34.397,150.644 but I am getting back the error: Caused by: java.net.URISyntaxException: Illegal character in query at index 99: https://maps.googleapis.com/maps/api/elevation/json?locations=51.606013718523265,-8.432384161819547|51.606031961540985,-8.432374430210215|51.60607166348032,-8.432334651837888|51.60610446039263,-8.4322494395575&key=myAPIkey It works if I just send a single point. I am told to use the pipe ('|') character yet it won't accept it. My code is

 position = ellipsePositions.get(index1);              
 longitude = position.getLongitude();
 latitude = position.getLatitude();
 APIstring = latitude + "," + longitude;

 for (int index = 1; index < indexList.size(); index++)
 {
    if (ellipsePositions.get(index) != null)
    { 
       position = ellipsePositions.get(index);              
       longitude = position.getLongitude();
       latitude = position.getLatitude();
       APIstring = APIstring + "|" +  latitude + "," + longitude;
    }
 }   

and

WebResource webResource =   client.resource("https://maps.googleapis.com/maps/api/elevation/json?locations="+ APIstring + "&key=myAPIkey");
ClientResponse response = webResource.accept("application/json").get(ClientResponse.class);
String data = response.getEntity(String.class);

Can anyone help?

Answer 1

You need to URL encode any "unsafe" characters in the query string. Per the documentation on web services

Building a Valid URL

You may think that a "valid" URL is self-evident, but that's not quite the case. A URL entered within an address bar in a browser, for example, may contain special characters (eg "上海+中國"); the browser needs to internally translate those characters into a different encoding before transmission. By the same token, any code that generates or accepts UTF-8 input might treat URLs with UTF-8 characters as "valid", but would also need to translate those characters before sending them out to a web server. This process is called URL-encoding.

We need to translate special characters because all URLs need to conform to the syntax specified by the W3 Uniform Resource Identifier specification. In effect, this means that URLs must contain only a special subset of ASCII characters: the familiar alphanumeric symbols, and some reserved characters for use as control characters within URLs.

Some common characters that must be encoded are:

Unsafe character   Encoded value
|                  %7C