如何在VolleyPlus中使用Spinner在addStringParam中将输入作为字符串

Question

这是将微调项目用作发送电子邮件的输入的代码，但是我无法获取addStringParam中的项目值。如何将微调器值作为字符串发送？我的API使用的是volleySingleton。

String[] country = {
    "India",
    "USA",
    "China",
    "Japan",
    "Other"
};

final Spinner spin = (Spinner) findViewById(R.id.spinner);

ArrayAdapter aa = new ArrayAdapter(this, android.R.layout.simple_spinner_item, country);
aa.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spin.setAdapter(aa);

spin.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {@Override
    public void onItemSelected(AdapterView < ?>parent, View view, int position, long id) {
        String crustItem = spin.getSelectedItem().toString();

        TextView displayTextView = (TextView) findViewById(R.id.displayTextView);
        displayTextView.setText((String) parent.getItemAtPosition(position));
        spin.setOnItemSelectedListener(this);

        Object item = parent.getItemAtPosition(position);

    }

    @Override
    public void onNothingSelected(AdapterView < ?>parent) {

}
});

String spintext = spin.getSelectedItem().toString().trim();

Textview massagetype = findViewById(R.id.book_massagetype);
bookNow = findViewById(R.id.book_button);

bookNow.setOnClickListener(new View.OnClickListener() {@Override
    public void onClick(View v) {
        boolean b = validateForm();
        if (b) {
            callingvolley();
        }
    }
});
} 

// Use volley singleton for access api 
private void callingvolley() {

    String url = "http://massagebudget.com/app/webservices/api.php?apicall=booking";
    SimpleMultiPartRequest simpleMultiPartRequest = new SimpleMultiPartRequest(Request.Method.POST, url, new Response.Listener < String > () {

        // Access values in String format
        ;

        simpleMultiPartRequest.addStringParam("massage_type", spintext.getText().toString());
        simpleMultiPartRequest.addStringParam("message", message.getText().toString());
        VolleySingleton.getInstance(this).addToRequestQue(simpleMultiPartRequest);

    }
}