使用Android Studio+Spring Boot+MySQL数据库实现博客APP

String url=getString(R.string.serverurl)+"user/loginConfirm";
                System.out.println(url);
                RequestParams params = new RequestParams();
                params.put("username",username);
                params.put("password",password);
                final AsyncHttpClient client = new AsyncHttpClient();
                client.post(url,params,new AsyncHttpResponseHandler(){

                    @Override
                    public void onSuccess(int i, Header[] headers, byte[] bytes) {
                        try {
                            String username = login_username.getText().toString().trim();
                            String password = login_password.getText().toString().trim();
                            //判断是否成功
                            String json = new String(bytes,"utf-8");
                            NewsUser newsUser = JsonParse.getNewsUser(json);
                            if(newsUser==null){
                                Toast.makeText(LoginActivity.this,"用户名或密码错误",Toast.LENGTH_SHORT).show();
                            }else{
                                //存储
                                boolean isSaveSuccess = SPSaveAcount.saveUserInfo(LoginActivity.this,username,password);
                                if(isSaveSuccess){
                                    Intent intent=new Intent();
                                    intent.setClass(LoginActivity.this,MainActivity.class);
                                    intent.putExtra("username",username);
                                    startActivity(intent);
                                    LoginActivity.this.finish();
                                }else{
                                    Toast.makeText(LoginActivity.this,"出现问题，请重新尝试",Toast.LENGTH_SHORT).show();
                                }
                            }

                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                    }
                    @Override
                    public void onFailure(int i, Header[] headers, byte[] bytes, Throwable throwable) {
                        Toast.makeText(LoginActivity.this,"请求失败",Toast.LENGTH_SHORT).show();
                    }
                });

博主，这段Android代码的AsyncHttpClient这个方法无法向后端请求数据应该怎么调试呢。url是对的，后端的代码单独用postman也可以请求数据测试成功，应该怎么办