在MI或Xiaomi手机android上获取mac地址

Question

我正在使用以下代码来获取移动设备的mac地址，并且它在android设备上可以正常工作。从stackoverflow获取我的mac地址的代码。但是在MI或Xiaomi手机上，获取mac地址无法正常工作。下面是我的代码。用户输入手机号码即可访问该应用，然后将在url中发送mac地址

public class MainActivity extends AppCompatActivity {
 @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
 public void onClick(View view) {
            ConnectivityManager ConnectionManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo networkInfo = ConnectionManager.getActiveNetworkInfo();
            if (networkInfo != null && networkInfo.isConnected() == true) {
                //get data from screen
                getMacAddr();
                mobile = mobile_no.getText().toString();
                String url = "https://sugarapp.web4rest.com/verify_user.php?mobile="+mobile+"&mac="+mac_addr;
                    if(mobile.isEmpty() || !mobile.matches(MOBILE_PATTERN)) {
                    builder.setTitle("Something went wrong!!");
                    displayAlert("You have not entered Mobile Number");
                }else {
                    final ProgressDialog progressDialog = new ProgressDialog(MainActivity.this);
                    progressDialog.setMessage("Please Wait...");
                    progressDialog.show();
                    StringRequest stringRequest = new StringRequest(Request.Method.GET, url,
                            new Response.Listener<String>() {
                                @Override
                                public void onResponse(String response) {
                                    try {
                                        progressDialog.dismiss();
                                        JSONObject jobject = new JSONObject(response);
                                        if (Integer.parseInt(jobject.getString("status")) == 200) {
                                            Toast.makeText(getApplicationContext(), "Login Success", Toast.LENGTH_LONG).show();
                                            mobile_no.setText("");
                                            port_no.setText("");
                                            session.setLoggedin(true);
                                            getData(); //Shared p call
                                            Intent i = new Intent(MainActivity.this, ReportActivity.class);
                                            startActivity(i);
                                            finish();
                                        } else {
                                            Toast.makeText(getApplicationContext(), "Login Unsuccessfull", Toast.LENGTH_LONG).show();
                                        }

                                    } catch (JSONException e) {
                                        progressDialog.dismiss();
                                        Log.e("Error", "Login Failed" + e.toString());
                                        e.printStackTrace();
                                        Toast.makeText(MainActivity.this, "Error", Toast.LENGTH_SHORT);
                                    }
                                }
                            }, new Response.ErrorListener() {
                        @Override
                        public void onErrorResponse(VolleyError error) {
                            progressDialog.dismiss();
                            Toast.makeText(MainActivity.this, "Error", Toast.LENGTH_SHORT);
                            error.printStackTrace();
                        }
                    }) {
                        @Override
                        protected Map<String, String> getParams() throws AuthFailureError {
                            Map<String, String> parmams = new HashMap<String, String>();
                            parmams.put("mobile_no", mobile);
                            parmams.put("mac", mac_addr);
                            return parmams;
                        }
                    };
                    MySingleton.getInstance(MainActivity.this).addToRequestque(stringRequest);
                }

            }else {
                Toast.makeText(MainActivity.this, "Network Unavailable", Toast.LENGTH_LONG).show();
            }
        }
    });
}
public String getMacAddr() {
    try {
        List<NetworkInterface> all = Collections.list(NetworkInterface.getNetworkInterfaces());
        for (NetworkInterface nif : all) {
            if (!nif.getName().equalsIgnoreCase("wlan0")) continue;

            byte[] macBytes = nif.getHardwareAddress();
            if (macBytes == null) {
                return "";
            }

            StringBuilder res1 = new StringBuilder();
            for (byte b : macBytes) {
                res1.append(Integer.toHexString(b & 0xFF) + ":");
            }

            if (res1.length() > 0) {
                res1.deleteCharAt(res1.length() - 1);
            }
            mac_addr = res1.toString();
            return mac_addr;
        }
    } catch (Exception ex) {
        //handle exception
    }
    return "";
}