如何在android中发布参数并将数据作为JSONObject返回？答案

【问题标题】：How to POST params in android and GET data back as JSONObject?如何在android中发布参数并将数据作为JSONObject返回？
【发布时间】：2019-07-09 07:35:41
【问题描述】：

我必须发布用户名、密钥和另一个参数才能将数据作为 JSONObject 获取并在 RecyclerView 中显示它们。我在android中使用Volley Library，尝试了所有可能的方法，但它们都没有帮助.. 即使通过 Postman 进行测试似乎工作正常，并且当我发布这三个参数时我得到了数据，但我不知道我在 android 中缺少什么..

PHP 代码：

<?php

require("db/Db.class.php");





if(isset($_POST['key']) && isset($_POST['username']) && isset($_POST['getMainCategory'])){

    $db = new DB();

    $username = $_POST['username'];

    $key = $_POST['key'];

    $query = $db->query("SELECT * FROM oc_api where `username` = '$username' and `key` = '$key' limit 1 ");



    if(count($query) == 0){

        $json = ["error don't have permittion"];

    }else{

        $catigory = $db->query("SELECT * FROM `oc_category_description`,oc_category WHERE oc_category_description.category_id = oc_category.category_id and oc_category.status = 1 and oc_category.parent_id = 0 and oc_category_description.language_id = 2");

        $json = $catigory;

    }



    header('Content-Type: application/json');

    echo json_encode($json);

    return;

}



if(isset($_POST['key']) && isset($_POST['username']) && isset($_POST['getSlideShow'])){

    $db = new DB();

    $username = $_POST['username'];

    $key = $_POST['key'];

    $slideShowId = (int)$_POST['getSlideShow'];

    $query = $db->query("SELECT * FROM oc_api where `username` = '$username' and `key` = '$key' limit 1 ");



    if(count($query) == 0){

        $json = ["error don't have permittion"];

    }else{

        $banderSlideShow = $db->query("SELECT * FROM `oc_banner_image` where `banner_id` = $slideShowId and language_id = 2");

        $json = $banderSlideShow;

    }

    header('Content-Type: application/json');

    echo json_encode($json);

    return;

}



if(isset($_POST['key']) && isset($_POST['username']) && isset($_POST['getAllNews'])){

    $db = new DB();

    $username = $_POST['username'];

    $key = $_POST['key'];

    $query = $db->query("SELECT * FROM oc_api where `username` = '$username' and `key` = '$key' limit 1 ");



    if(count($query) == 0){

        $json = ["error don't have permittion"];

    }else{

        $catigory = $db->query("SELECT * FROM `oc_blog_article`,`oc_blog_article_description` WHERE oc_blog_article_description.blog_article_id = oc_blog_article.blog_article_id and oc_blog_article.status = 1 and oc_blog_article_description.language_id = 2 order by oc_blog_article.sort_order");

        $json = $catigory;

    }



    header('Content-Type: application/json');

    echo json_encode($json);

    return;

}



$json = ["error"];

header('Content-Type: application/json');

echo json_encode($json);



?>

JAVA代码：

public static final String URL_PRODUCTS = "http://vinsmartangle.net/shop/myApi/index.php";

 private void loadProducts(final String user, final String api,final String no) {

        StringRequest stringRequest = new StringRequest(Request.Method.POST, URL_PRODUCTS,
                new Response.Listener<String>() {
                    @Override
                    public void onResponse(String response) {
                        try {

                            //converting the string to json array object
                            JSONArray array = new JSONArray(response);

                            //traversing through all the object
                            for (int i = 0; i < array.length(); i++) {

                                //getting product object from json array
                                JSONObject category = array.getJSONObject(i);

                                String id = category.getString("category_id");
                                String name = category.getString("name");
                                Category data = new Category();

                                //adding the product to product list
                                data.setCategoryNo(id);
                                data.setCategoryName(name);

                                        categoryList.add(data);

                            }
                            categoryAdapter = new CategoryAdapter(getActivity(),categoryList, Fragment_Payment.this);
                            recyclerView.setAdapter(categoryAdapter);


                        } catch (JSONException e) {
                            e.printStackTrace();

                        }
                        catch (JsonParseException e)
                        {
                            e.printStackTrace();
                        }

                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {

                        Log.d(TAG, "onErrorResponse: Error ", error.getCause());

                    }
                })
        {
            @Override
            protected Map<String,String> getParams(){
                Map<String,String> params = new HashMap<String, String>();

                params.put("username ",user);
                params.put("key",api);
                params.put("getMainCategory",no);
                return params;
            }

            @Override
            public Map<String, String> getHeaders() throws AuthFailureError {
                Map<String,String> headers = new HashMap<String, String>();
                headers.put("Content-Type", "application/json");


                return headers;
            }
        };

        //adding our stringrequest to queue
        Volley.newRequestQueue(getActivity()).add(stringRequest);
    }

邮递员Screenshot:

[
    {
        "category_id": "20",
        "language_id": "2",
        "name": "رمان",
        "description": "&lt;p&gt;&lt;br&gt;&lt;\/p&gt;",
        "meta_title": "رمان",
        "meta_description": "مثال لوصف القسم",
        "meta_keyword": "",
        "image": "catalog\/demo\/compaq_presario.jpg",
        "image_Icon": "",
        "parent_id": "0",
        "top": "1",
        "column": "1",
        "sort_order": "1",
        "status": "1",
        "date_added": "2009-01-05 21:49:43",
        "date_modified": "2019-07-03 01:53:35"
    },
    {
        "category_id": "83",
        "language_id": "2",
        "name": "خضروات",
        "description": "",
        "meta_title": "خضروات",
        "meta_description": "",
        "meta_keyword": "",
        "image": "",
        "image_Icon": "",
        "parent_id": "0",
        "top": "1",
        "column": "1",
        "sort_order": "2",
        "status": "1",
        "date_added": "2019-07-04 11:05:33",
        "date_modified": "2019-07-05 06:16:54"
    },
    {
        "category_id": "85",
        "language_id": "2",
        "name": "ورقيات",
        "description": "",
        "meta_title": "ورقيات",
        "meta_description": "",
        "meta_keyword": "",
        "image": "",
        "image_Icon": "",
        "parent_id": "0",
        "top": "0",
        "column": "1",
        "sort_order": "0",
        "status": "1",
        "date_added": "2019-07-04 11:06:41",
        "date_modified": "2019-07-04 11:06:41"
    },
    {
        "category_id": "90",
        "language_id": "2",
        "name": "عسل",
        "description": "",
        "meta_title": "عسل",
        "meta_description": "",
        "meta_keyword": "",
        "image": "",
        "image_Icon": "",
        "parent_id": "0",
        "top": "1",
        "column": "1",
        "sort_order": "0",
        "status": "1",
        "date_added": "2019-07-04 11:08:56",
        "date_modified": "2019-07-05 11:59:46"
    },
    {
        "category_id": "87",
        "language_id": "2",
        "name": "صناديق",
        "description": "",
        "meta_title": "صناديق",
        "meta_description": "",
        "meta_keyword": "",
        "image": "",
        "image_Icon": "",
        "parent_id": "0",
        "top": "1",
        "column": "1",
        "sort_order": "0",
        "status": "1",
        "date_added": "2019-07-04 11:07:43",
        "date_modified": "2019-07-05 11:59:30"
    },
    {
        "category_id": "57",
        "language_id": "2",
        "name": "فواكة موسمية",
        "description": "&lt;p&gt;&lt;br&gt;&lt;\/p&gt;",
        "meta_title": "فواكة موسمية",
        "meta_description": "",
        "meta_keyword": "",
        "image": "",
        "image_Icon": "",
        "parent_id": "0",
        "top": "1",
        "column": "1",
        "sort_order": "3",
        "status": "1",
        "date_added": "2011-04-26 08:53:16",
        "date_modified": "2019-07-03 01:52:47"
    },
    {
        "category_id": "89",
        "language_id": "2",
        "name": "مشروبات",
        "description": "",
        "meta_title": "مشروبات",
        "meta_description": "",
        "meta_keyword": "",
        "image": "",
        "image_Icon": "",
        "parent_id": "0",
        "top": "0",
        "column": "1",
        "sort_order": "0",
        "status": "1",
        "date_added": "2019-07-04 11:08:01",
        "date_modified": "2019-07-04 11:08:01"
    }
]

当我运行应用程序时，我得到了这个异常：

W/System.err: org.json.JSONException: Value error at 0 of type java.lang.String cannot be converted to JSONObject
        at org.json.JSON.typeMismatch(JSON.java:101)
        at org.json.JSONArray.getJSONObject(JSONArray.java:525)
W/System.err:     at com.smart.mangojazan.Fragment_Payment$1.onResponse(Fragment_Payment.java:117)
        at com.smart.mangojazan.Fragment_Payment$1.onResponse(Fragment_Payment.java:105)
        at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:82)
        at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:29)
        at com.android.volley.ExecutorDelivery$ResponseDeliveryRunnable.run(ExecutorDelivery.java:102)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
W/System.err:     at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7050)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:965)

【问题讨论】：

代码看起来不错，你有没有调试看看有什么响应？
好的，所以你在解码 json 时遇到错误。API 和 volley 工作正常。使用 gson 解码 json 。这将解决您的问题。
@AhmadAyyaz 是的。我收到回复：["error"]
@JawadAhmed 它不起作用，因为我没有得到 Json 数组，我只得到这个字符串 "["error"]"
那么您的 API 没有发送正确的响应。那里少了点什么。 API 应该返回正确的响应。您的代码尝试从 JSONArray 获取 JSONObject，但您的响应中数组内没有对象，并且在解析时给出异常

标签： java php android android-volley

【解决方案1】：

您已完成所有代码，并且在发送响应之前已设置 json=["error"];

[不要忘记接受答案并在答案正确或阐明（解释更多）您的问题，以便回答者可以给出更相关的答案]

<?php

require("db/Db.class.php");
if(isset($_POST['key']) && isset($_POST['username']) && isset($_POST['getMainCategory'])){
    //your code

    //remove below two lines from every if as it can be called commonly at last;
    //header('Content-Type: application/json');
    //echo json_encode($json);
}else if(isset($_POST['key']) && isset($_POST['username']) && isset($_POST['getSlideShow'])){
    //your code
}else if(isset($_POST['key']) && isset($_POST['username']) && isset($_POST['getAllNews'])){
    //your code
}else{
    $json = ["error"];
}

header('Content-Type: application/json');
echo json_encode($json);
?>

【讨论】：

【解决方案2】：

由于您期待 JSONArray，因此不要使用 StringRequest，而是使用 volley 中可用的 JsonArrayRequest。请参阅此文档：https://developer.android.com/training/volley/request

你的错误日志也显示

java.lang.String 无法转换为 JSONObject

因此我建议你试试这个：

JsonArrayRequest req = new JsonArrayRequest(Request.Method.POST, URL_PRODUCTS,
            new Response.Listener<String>() {
                @Override
                public void onResponse(JSONArray response) {
             //.............

因为你期待一个 json 数组。

【讨论】：

响应是 JSONArray

【解决方案3】：

我解决了这个问题，实际上这很荒谬.. 有一点空间在第一个 params.put 中的“用户名”旁边，这导致了无法获取数据并导致异常的问题..即使我仔细检查了但不知道我是如何错过的..感谢所有花时间尝试的人来帮助我。我很感激。

@Override
            protected Map<String,String> getParams(){
                Map<String,String> params = new HashMap<String, String>();
       //the line below was causing the exception. right side of "username " (space)
                params.put("username ",user);
                params.put("key",api);
                params.put("getMainCategory",no);
                return params;
            }

【讨论】：