接口的调用

 public String callServer(String askUrl,String json){

        StringBuffer sb = new StringBuffer(""); //输出的结果

        try {
            URL url = new URL(askUrl);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setDoOutput(true);
            connection.setDoInput(true);
            connection.setRequestMethod("POST");
            connection.setUseCaches(false);//不使用缓存
            connection.setInstanceFollowRedirects(true);//自动重定向
            connection.setRequestProperty("connection", "Keep-Alive");
            connection.setRequestProperty("Accept", "application/json"); // 设置接收数据的格式
            connection.setRequestProperty("Content-Type", "application/json"); // 设置发送数据的格式
            //连接
            connection.connect();
            //POST请求
            OutputStreamWriter out = new OutputStreamWriter(connection.getOutputStream(),"UTF-8");

            out.write(json);

            System.out.println("data======="+json);

            out.flush();
            out.close();
            //读取响应
            BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            String lines;

            while ((lines = reader.readLine()) != null) {
                lines = new String(lines.getBytes(), "utf-8");
                sb.append(lines);
            }
            System.out.println(sb.toString());
            reader.close();
            connection.disconnect();
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return sb.toString();
    }