OkHttp3设置Content-Type

private void connectToApi(String requestMsg, String bizCode) throws IOException {        try {            OkHttpClient okHttpClient = this.createClient();            Logger.t("request").d(url.toString());            /**             * 创建请求的参数body             */            RequestBody body = FormBody.create(MediaType.parse("application/json"), requestMsg);            Request request = new Request.Builder()                    .url(url)                    .post(body)                    .build();            Response response = okHttpClient.newCall(request).execute();            if (response.isSuccessful()) {                this.response = response.body().string();            } else {                throw new IOException("无法连接到服务器，请检查网络连接");                //throw new IOException("Unexpected code " + response);            }        } catch (IOException e) {            e.printStackTrace();            throw new IOException("网络有点卡...");        }    }