使用 Android Volley 库和 API

Question

我是 Android Volley 库的新手。我将用户名和密码发送到 API，API 返回用户详细信息。所以这是我在 android 中的 LoginUser 方法。

public void LoginUser(){

    // Tag used to cancel the request
    String tag_json_obj = "json_obj_req";

    String url = "http://example.com/myfile/mobile_api/";

    //final ProgressDialog pDialog = ProgressDialog.show(getParent(), "Please wait", "Login user");


            JsonObjectRequest jsonObjReq = new JsonObjectRequest(Method.GET,
                    url, null,
                    new Response.Listener<JSONObject>() {

                        @Override
                        public void onResponse(JSONObject response) {
                            try {
                                if(response.getString(KEY_SUCCESS)!=null){

                                    String res = response.getString(KEY_SUCCESS);

                                    if(Integer.parseInt(res) == 1){
                                       JSONObject json_user = response.getJSONObject("user");
                                       Toast.makeText(getApplicationContext(), "User Logged in.. " + json_user.getString("name"), Toast.LENGTH_LONG).show();
                                    }
                                }
                                else if(response.getString(KEY_ERROR)!=null){

                                    String res = response.getString(KEY_ERROR);

                                    if(Integer.parseInt(res) == 1){
                                        Toast.makeText(getApplicationContext(), response.getString("error_msg"), Toast.LENGTH_LONG).show();
                                    }
                                }

                            } catch (JSONException e) {
                                // TODO Auto-generated catch block
                                e.printStackTrace();
                                //pDialog.hide();
                            }
                            Log.d(TAG, response.toString());
                            //pDialog.hide();
                        }
                    }, new Response.ErrorListener() {

                        @Override
                        public void onErrorResponse(VolleyError error) {
                            VolleyLog.d(TAG, "Error: " + error.getMessage());
                            Log.d(TAG, "Error: " + error.getMessage());
                            //pDialog.hide();
                        }
                    }) {

                @Override
                protected Map<String, String> getParams() {
                    Map<String, String> params = new HashMap<String, String>();
                    params.put("tag", login_tag);
                    params.put("email", Email);
                    params.put("password", Pass);

                    return params;
                }

            };

    // Adding request to request queue
    AppController.getInstance().addToRequestQueue(jsonObjReq, tag_json_obj);
}

这是我的 API index.php 文件

if ($tag == 'login') {

    $email = $_POST['email'];
    $password = $_POST['password'];


    $user = $db->getUserByEmailAndPassword($email, $password);
    if ($user != false) {

        $response["success"] = 1;
        $response["uid"] = $user["id"];
        $response["user"]["name"] = $user["name"];
        $response["user"]["phone"] = $user["contact_no"];
        $response["user"]["email"] = $user["email"];
        $response["user"]["reg_date"] = $user["reg_date"];
        echo json_encode($response);
    } else {

        $response["error"] = 1;
        $response["error_msg"] = "Incorrect email or password!";
        echo json_encode($response);
    }

但我收到来自 Json 的以下错误

07-31 16:58:27.307: E/JSON Parser(7506): 解析数据时出错 org.json.JSONException: 类型 java.lang.String 的值不能转换为 JSONObject

那么这是使用 Volley 连接移动 API 和 Android 应用程序的正确方法吗？或者谁能​​解释我这样做的原因？

Answer 1

嗯，我想我找到了问题所在。我收到该错误消息，因为如果标签不正确，它会返回字符串“拒绝访问”，它会给出“拒绝访问”消息。所以这不是一个 json 对象，它只是一个字符串。要解决该错误，您可以使用 String Request 来获取字符串值。

StringRequest strReq = new StringRequest(Method.POST, //here change the method to POST
            Const.URL_STRING_REQ, new Response.Listener<String>() {

                @Override
                public void onResponse(String response) {
                    Log.d(TAG, response.toString());
                    msgResponse.setText(response.toString());
                    hideProgressDialog();

                }
            }, new Response.ErrorListener() {

                @Override
                public void onErrorResponse(VolleyError error) {
                    VolleyLog.d(TAG, "Error: " + error.getMessage());
                    hideProgressDialog();
                }


            }){

        @Override
            protected Map<String, String> getParams() {
                Map<String, String> params = new HashMap<String, String>();
                params.put("tag", login_tag);
                params.put("email", Email);
                params.put("password", Pass);

                return params;
            }
    };