最近一直在做演算法模型等等，好久不碰系統開發這套東西，頂多自己做個ETL寫個spark，正巧自己準備資料的過程中需要呼叫服務獲得一批資料，難得的非常有趣，程式碼極其基礎簡單，記錄下來也不錯

import org.codehaus.jettison.json.JSONObject;

import java.io.*;
import java.net.URL;
import java.net.URLConnection;
import java.util.HashMap;
import java.util.Map;

public static double calArea(String fence) throws Exception {
        String service = "http://hahhhh"
 
;
        //簡單粗暴的的GET請求方式，引數過長會報錯，所以採用POST方式
//                +"?" +
//                "coor=" +
//                fence
////                "116.3205,39.97502;116.315,39.88867;116.39328,39.88867;116.3205,39.97502"
//                +"&ak=hahhhh";
        URL url = new URL(service);
        URLConnection conn = url.openConnection();
        conn.setRequestProperty("accept"
 
, "*/*");
        conn.setRequestProperty("connection", "Keep-Alive");
        conn.setRequestProperty("user-agent",
                "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
        conn.setDoOutput(true);
        conn.setDoInput(true);

        //POST請求方式
        PrintWriter fw = null;
        fw = new
 
 PrintWriter(conn.getOutputStream());
        fw.print("coor=" +
                fence
//                "116.3205,39.97502;116.315,39.88867;116.39328,39.88867;116.3205,39.97502"
                +
                "&ak=hahhhh");
        fw.flush();

        //GET請求方式
//        conn.connect();
        //        Map<String, List<String>> map = conn.getHeaderFields();
//        for(String key:map.keySet()){
//            System.out.println(map.get(key));
//        }

        //讀取服務返回結果
        BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        String line;
        String res = "";
        if ((line = br.readLine()) != null) {
            JSONObject jo = new JSONObject(line);
            res = jo.getJSONObject("result").getString("polygonarea");
        }
        return Double.parseDouble(res);
    }