Android 向远程网站发送数据问题，变量和常量的区别。求大神解答。。。

Question

        Button button = (Button) findViewById(R.id.button);
    button.setOnClickListener(
            new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                //  boolean flag = sendUserInfo();
                    Map<String, String> params = new HashMap<String, String>();
                    String tmp1 = cardInfo;//cardInfo为在程序中的变量
                    String tmp2 = locationInfo;//locationInfo为在程序中的变量
                // 发送上边两个cardInfo、locationInfo就不行，发送下边的常量"123"和"234"就可以
                //  String tmp1 = "123";
                //  String tmp2 = "234";
                    params.put("sj", tmp1);
                    params.put("dw", tmp2);
                    boolean flag = false;
                    try {
                        flag = sendPOSTRequest(path, params, "UTF-8");
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                    Toast.makeText(MainActivity.this, flag+"\t"+locationInfo, Toast.LENGTH_LONG).show();
                }
        });


public static Boolean sendPOSTRequest(String path,Map<String, String> params, String encoding) throws Exception {
    StringBuilder url = new StringBuilder(path);
    if(params != null && params.size() > 0){
        url.append('&');
        for (Map.Entry<String, String> entry : params.entrySet()) {
            url.append(entry.getKey()).append("=");
            url.append(URLEncoder.encode(entry.getValue(), encoding));// 编码
            url.append('&');
        }
        url.deleteCharAt(url.length() - 1);
    }
    Log.e("url",url.toString());
    HttpURLConnection connection = (HttpURLConnection) new URL(url.toString()).openConnection();// 基于HTTP协议连接对象
    connection.setConnectTimeout(5000);
    connection.setRequestMethod("POST");
    if (connection.getResponseCode() == 200) {
        return true;
    }else{
        return false;
    }
}