使用Google Elevation API获取海拔高度（java版）

Google Elevation API提供了根据某地经纬度获取该地点海拔高度的接口。开发者可以调用该API获取地点的海拔信息。使用Google Elevation API之前，用户首先需要注册为Google Developer，获取API key。

开发者可以查看API的调用记录，目前Elevation API的限制次数为2500次/每天，每次API访问的字节数小于2000字符。

相应的Java代码如下所示：

package elevation;

import java.io.*;
import java.net.*;
import javax.xml.parsers.ParserConfigurationException;
import org.xml.sax.SAXException;

/**
 *
 * @author yfeng14
 */
public class Elevation {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        StringBuffer document = new StringBuffer();
        try {
            //Elevation API URLs are restricted to approximately 2000 characters
            URL url = new URL("https://maps.googleapis.com/maps/api/elevation/xml?locations=39.7391536,-104.9847034|39.7391536,-104.9847034&key=YourKEY");//远程url
            URLConnection conn = url.openConnection();
            BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
            String line = null;
            while ((line = reader.readLine()) != null) {
                if (line.startsWith("  <elevation>")) {
                    line = line.replaceAll("  <elevation>", "");
                    line = line.replaceAll("</elevation>", "");
                    document.append(line + " ");
                    System.out.println(line);
                }
            }
            reader.close();
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        String xml = document.toString();//返回值
        System.out.print(xml);
    }
}