企业微信发送、撤回消息 java代码

public class SendToWX {

    //获取token
    String access_token = getToken();
    //请求串
    String url = SEND_MESSAGE_URL + access_token;

    //拼接请求JSON字符串
    StringBuffer stringBuffer = new StringBuffer();
        stringBuffer.append("{");
        stringBuffer.append(""msgid":""+msgid);
        stringBuffer.append(""");
        stringBuffer.append("}");
    String json = stringBuffer.toString();
        try {
        URL postUrl = new URL(url);
        HttpURLConnection http = (HttpURLConnection) postUrl.openConnection();
        http.setRequestMethod("POST");
        http.setRequestProperty("Content-Type", "application/json;charset=UTF-8");
        http.setDoOutput(true);
        http.setDoInput(true);
        // 连接超时30秒
        System.setProperty("sun.net.client.defaultConnectTimeout", "30000");
        // 读取超时30秒
        System.setProperty("sun.net.client.defaultReadTimeout", "30000");
        http.connect();

        //写入内容
        OutputStream outputStream = http.getOutputStream();
        outputStream.write(json.getBytes("UTF-8"));
        InputStream inputStream = http.getInputStream();
        int size = inputStream.available();
        byte[] jsonBytes = new byte[size];
        //将腾讯返回的内容读入
        inputStream.read(jsonBytes);
        String message = new String(jsonBytes, "UTF-8");
        JSonObject jsonObject  = (JSONObject) JSONObject.parse(message);

        System.out.println("微信返回的消息：" + jsonObject.toString());
        //清空输出流
        outputStream.flush();
        //关闭输出通道
        outputStream.close();
    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (ProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

}