okHttp使用post传递json

private void easeRegist(final String objectId) {
        JSONObject object=new JSONObject();
        try {
            object.put("username", objectId);
            object.put("password", "abcd1234");
            object.put("nickname", objectId);
            final MediaType JSON = MediaType.parse("application/json; charset=utf-8");
            OkHttpClient client = HttpUtils.getInstance().clone();
            RequestBody body = RequestBody.create(JSON, object.toString());
            Request request = new Request.Builder().addHeader("Content-Type", "application/json").url(ParamsUtil.HXUsers).post(body).build();
            client.newCall(request).enqueue(new Callback() {
                @Override
                public void onFailure(Request request, IOException e) {
                    Toast.makeText(SplashActivity.this, "注册失败，APP将要退出", Toast.LENGTH_SHORT).show();
                    finish();
                }

                @Override
                public void onResponse(Response response) throws IOException {
                    if (response.isSuccessful()) {
                        Log.d("SplashActivity", response.body().string());

                        // 保存用户名
                        HXUtils.setUserName(objectId, ((MyApplication) SplashActivity.this.getApplicationContext()).hxSDKHelper);
                        HXUtils.setPassword("abcd1234", ((MyApplication) SplashActivity.this.getApplicationContext()).hxSDKHelper);

                        easeLogin();
                    }
                    else {
                        if (response.code()==400) {
                            // 保存用户名
                            HXUtils.setUserName(objectId, ((MyApplication) SplashActivity.this.getApplicationContext()).hxSDKHelper);
                            HXUtils.setPassword("abcd1234", ((MyApplication) SplashActivity.this.getApplicationContext()).hxSDKHelper);

                            easeLogin();
                        }
                    }
                }
            });
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }