PHP：POST数据丢失。 .htaccess文件中可能存在的错误？

Question

在Android中使用Volley库，我使用POST方法将数据发送到服务器。

private void registerNewUser(final String name, final String email, final String password) {
    final String TAG_REGISTER = "New user registration";

    String tag_string_req = "req_register";

    final ProgressDialog pDialog = new ProgressDialog(getActivity());
    pDialog.setCancelable(true);

    pDialog.setMessage("Registering..");
    pDialog.show();

    JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Method.POST, ServerURL.URL_REGISTER, new Response.Listener<JSONObject>() {

        @Override
        public void onResponse(JSONObject response) {
            Log.d(TAG_REGISTER, "Register Response: " + response.toString());
            pDialog.dismiss();

            try {
                JSONObject jObj = new JSONObject(response.toString());
                boolean error = jObj.getBoolean("error");
                if (!error) {
                    // User successfully stored in MySQL
                    // Now store the user in sqlite
                    String uid = jObj.getString("uid");

                    JSONObject user = jObj.getJSONObject("user");
                    String name = user.getString("name");
                    String email = user.getString("email");
                    String created_at = user
                            .getString("created_at");

                    // Inserting row in users table
                    db.addUserIntoSQLite(name, email, uid, created_at);

                    Toast.makeText(getActivity(), "User successfully registered. Try login now!", Toast.LENGTH_LONG).show();

                    // Launch login activity
                    Intent intent = new Intent(getActivity(), MainActivity.class);
                    startActivity(intent);

                } else {

                    // Error occurred in registration. Get the error
                    // message
                    String errorMsg = jObj.getString("error_msg");
                    Toast.makeText(getActivity(), errorMsg, Toast.LENGTH_LONG).show();
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }

        }
    }, new Response.ErrorListener() {

        @Override
        public void onErrorResponse(VolleyError error) {
            Log.e(TAG_REGISTER, "Registration Error: " + error.getMessage());
            Toast.makeText(getActivity(), error.getMessage(), Toast.LENGTH_LONG).show();
            pDialog.dismiss();
        }
    }) {

        @Override
        protected Map<String, String> getParams() {
            // Posting params to register url
            Map<String, String> params = new HashMap<String, String>();
            params.put("tag", "register");
            params.put("name", name);
            params.put("email", email);
            params.put("password", password);

            return params;
        }

    };
    ApplicationController.getInstance().addToRequestQueue(jsonObjectRequest, tag_string_req);
}

这是获取POST数据的PHP部分。

<?php

if (isset($_POST['tag']) && $_POST['tag'] != '') {
    // get tag
    $tag = $_POST['tag'];

    // include db handler
    require_once 'mysql/DB_Functions.php';
    $db = new DB_Functions();

    // response Array
    $response = array("tag" => $tag, "error" => FALSE);

    // check for tag type
    if ($tag == 'register') {
        // Request type is Register new user
        $name = $_POST['name'];
        $email = $_POST['email'];
        $password = $_POST['password'];

        // check if user is already existed
        if ($db->isUserExisted($email)) {
            // user is already existed - error response
            $response["error"] = TRUE;
            $response["error_msg"] = "User already exists";
            echo json_encode($response);
        } else {
            // store user
            $user = $db->storeUser($name, $email, $password);
            if ($user) {
                // user stored successfully
                $response["error"] = FALSE;
                $response["uid"] = $user["unique_id"];
                $response["user"]["name"] = $user["name"];
                $response["user"]["email"] = $user["email"];
                $response["user"]["created_at"] = $user["created_at"];
                $response["user"]["updated_at"] = $user["updated_at"];
                echo json_encode($response);
            } else {
                // user failed to store
                $response["error"] = TRUE;
                $response["error_msg"] = "Error occured in Registartion";
                echo json_encode($response);
            }
        }
    } else {
        // user failed to store
        $response["error"] = TRUE;
        $response["error_msg"] = "Unknow 'tag' value. It should be either 'login' or 'register'";
        echo json_encode($response);
    }
} else {
    $response["error"] = TRUE;
    $response["error_msg"] = "Required parameter 'tag' is missing!";
    echo json_encode($response);
}
?>

现在，当我在这里运行registerNewUser（）方法时，它会显示标签丢失的Toast消息。正如您在PHP代码中看到的那样，错误消息＆＃34;必需参数＆＃39;标记＆＃39;缺少了！＆＃34;如果标记未设置或为空，则显示。

为什么即使我在Android代码中正确包含了标记变量，我也会收到该消息？

编辑：

我刚从Web服务器下载了.htaccess文件。我目前正在使用000webhost.com作为网络托管，它就像文件中的内容一样。

RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*) index.php

这些是我完全不知道的..这部分是否有错误阻碍了PHP中的POST请求？如果是这样，我该如何解决？