将QR扫描结果从android发送到PHP脚本

Question

是android编程的新手，我发现将qr scan的结果代码（使用Zxing）发送到我已经设置好的PHP文件时遇到了一些问题。扫描结果后，结果显示在警告对话框中，当我点击“继续”按钮时，应用程序崩溃。

 public void onActivityResult(int requestCode, int resultCode, Intent intent) {


    if (requestCode == 0) {
        if (resultCode == RESULT_OK) {
            contents = intent.getStringExtra("SCAN_RESULT");
            String format = intent.getStringExtra("SCAN_RESULT_FORMAT");
            // Handle successful scan
            //Toast toast = Toast.makeText(this, "Content:" + contents + " Format:" + format , Toast.LENGTH_LONG);
            //toast.setGravity(Gravity.TOP, 25, 400);
            //toast.show();
            Context context=this;
            AlertDialog.Builder builder1 = new AlertDialog.Builder(context);
            builder1.setMessage("Id Number: "+contents+"\n"+"Format: "+format);
            builder1.setCancelable(true);
            builder1.setNegativeButton(
                    "Continue",
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int id) {
                            checkLogin(contents);
                        }



                            //end

                    }

            );
            builder1.show();
        }
    }
             else if (resultCode == RESULT_CANCELED) {
        // Handle cancel
        Toast toast = Toast.makeText(this, "Scan was Cancelled!", Toast.LENGTH_LONG);

        toast.setGravity(Gravity.TOP, 25, 400);
        toast.show();
        new Thread(new Runnable() {
            public void run() {

            }
        }).start();

    }
        else{
            Toast toast = Toast.makeText(getApplicationContext(),
                    "No scan data received!", Toast.LENGTH_SHORT);
            toast.show();
        }
}

////////////////////////////////

public void checkLogin(final String contents) {
    //start


    String tag_string_req = "req_login";


    pDialog.setMessage("Logging in ...");
    showDialog();


    StringRequest strReq = new StringRequest(Request.Method.POST,
            REGISTER_URL, new Response.Listener<String>() {

        @Override
        public void onResponse(String response) {
            hideDialog();

            try {
                JSONObject jObj = new JSONObject(response);
                String userId = jObj.getString(TAG);

                if (userId != null) {
                    String successMsg = jObj.getString("success_msg");
                    Toast.makeText(getApplicationContext(),
                            successMsg, Toast.LENGTH_LONG).show();

                } else {
                    String errorMsg = jObj.getString("error_msg");
                    Toast.makeText(getApplicationContext(),
                            errorMsg, Toast.LENGTH_LONG).show();
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }

        }
    }, new Response.ErrorListener() {

        @Override
        public void onErrorResponse(VolleyError error) {
            Toast.makeText(getApplicationContext(),
                    error.getMessage(), Toast.LENGTH_LONG).show();
            hideDialog();
        }
    }) {

        @Override
        protected Map<String, String> getParams() {
            // Post params to login url
            Map<String, String> params = new HashMap<>();
            params.put(TAG, contents);

            return params;
        }

    };

    // Adding request to  queue
    AppController.getInstance().addToRequestQueue(strReq, tag_string_req);
}

private void showDialog() {
    if (!pDialog.isShowing())
        pDialog.show();
}

private void hideDialog() {
    if (pDialog.isShowing())
        pDialog.dismiss();
}