Question

我目前是第一次在android studio上的应用中工作。我目前面临一个问题，我不知道从哪里开始……我花了几个小时来寻找文档以及所有内容，但是我没有找到对我有用的东西。

所以我的应用程序是订购汉堡的应用程序。我从服务器获取数据时使用了我构建的API（一个简单的php文件，用于连接到db，获取我提供给应用程序的汉堡包），然后使用获取的数据进行查看。

当我在这里时，用户可以选择要订购的数量，然后需要将命令发送到服务器。但是我不知道该怎么做。我尝试了发现互联网的操作，但从未收到服务器响应。不精打细算会很难工作。这是我的应用程序设计： App View from user perspective

这是我的代码：

主要活动

public class MainActivity extends AppCompatActivity {
        ListView listView;

            @Override
            protected void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.activity_main);
                listView = findViewById(R.id.listView);
                downLoadJson("http://192.168.0.5/API/burger.php");
            }

            private void downLoadJson(final String urlWebService) {
                DownLoadJson getJson = new DownLoadJson(urlWebService, this);
                getJson.execute();
            }

        }

这是我的DownLoadJson类

import android.app.Activity;
import android.os.AsyncTask;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ListView;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;

public class DownLoadJson extends AsyncTask<Void, Void, String> {
    final String urlWebService;
    final Activity activity;
    private ArrayList<Burger> burgersList;

    public DownLoadJson(String url, Activity activity) {
        this.urlWebService = url;
        this.activity = activity;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        //Toast.makeText(activity.getApplicationContext(),"DOWNLOADING",Toast.LENGTH_LONG).show();
    }

    @Override
    protected void onPostExecute(String s) {
        super.onPostExecute(s);
        try {
            renderView(s);
            Button btnSend = activity.findViewById(R.id.btnSend);
            btnSend.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Log.d("ENVOYER", ""+burgersList.toString());
                    new SendPostRequestToServer().execute("http://192.168.0.5/API/ServiceCommandes.php",burgersList.toString());
                }
            });
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

    @Override
    protected String doInBackground(Void... voids) {
        try {
            // Ouverture de la connexion avec l'api
            URL url = new URL(urlWebService);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            StringBuilder stringBuilder = new StringBuilder();
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            String json;
            while ((json = bufferedReader.readLine()) != null) {
                stringBuilder.append(json + "\n");
            }
            return stringBuilder.toString().trim();
        } catch (MalformedURLException e) {
            Log.d("ERROR", "WRONG URL");
            e.printStackTrace();
            return null;
        } catch (IOException e) {
            Log.d("ERROR", "Connection I/O error ");
            e.printStackTrace();
            return null;
        } catch (Exception e) {
            return null;
        }
    }

    private void renderView(String json) throws JSONException {
        JSONArray jsonArray = new JSONArray(json);
        JSONObject jsonObject = jsonArray.getJSONObject(0);
        if (jsonObject.has("recette")) {
            burgersList = Burger.fromJson(jsonArray);
            BurgerAdapter adapter = new BurgerAdapter(activity, burgersList);
            ListView listView = (ListView) activity.findViewById(R.id.listView);
            listView.setAdapter(adapter);
            //adapter.addAll(burgersList);
            Log.d("DEBUG", "BURGER LIST = " + burgersList.size());
        }
    }

    public ArrayList<Burger> returnArrayList() {
        return burgersList;
    }
}

这是我找到互联网的我的SendPostRequestToServer

    import android.os.AsyncTask;
    import android.util.Log;

    import java.io.DataOutputStream;
    import java.io.InputStream;
    import java.io.InputStreamReader;
    import java.net.HttpURLConnection;
    import java.net.URL;

    public class SendPostRequestToServer extends AsyncTask<String, Void, String> {
        @Override
        protected String doInBackground(String... params) {

            String data = "";

            HttpURLConnection httpURLConnection = null;
            try {

                httpURLConnection = (HttpURLConnection) new URL(params[0]).openConnection();
                httpURLConnection.setRequestMethod("POST");

                httpURLConnection.setDoOutput(true);

                DataOutputStream wr = new DataOutputStream(httpURLConnection.getOutputStream());
                wr.writeBytes("PostData=" + params[1]);
                wr.flush();
                wr.close();

                InputStream in = httpURLConnection.getInputStream();
                InputStreamReader inputStreamReader = new InputStreamReader(in);

                int inputStreamData = inputStreamReader.read();
                while (inputStreamData != -1) {
                    char current = (char) inputStreamData;
                    inputStreamData = inputStreamReader.read();
                    data += current;
                }
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                if (httpURLConnection != null) {
                    httpURLConnection.disconnect();
                }
            }

            return data;
        }

        @Override
        protected void onPostExecute(String result) {
            super.onPostExecute(result);
            Log.e("POST :", result); // this is expecting a response code to be sent from your server upon receiving the POST data
        }
    }

Php文件：

<?php
// Headers
header("Access-Control-Allow-Origin: *");
header("Content-Type: application/json; charset=UTF-8");
header("Access-Control-Allow-Methods: POST");
$PostData = json_decode(file_get_contents("php://input"));
if(!empty(($PostData)){
    http_response_code(200);
    echo json_encode(array("message" => "DATA RECEIVE"));

}else{
    http_response_code(503);
    echo json_encode(array("message" => "DATA ERROR"));
}

$con=mysqli_connect("localhost","root","","fastfood");
// check erreur
if (mysqli_connect_errno())
{
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
mysqli_close($con);
?>

当我检查file_get_contents（“ php：// input”）; 我明白了： ''' 2020-06-16 15：16：06.174 12488-12488 / com.example.fastfood D / POST ::％5B％7B％22id％22％3A +％221％22％2C％22nom％22％3A +％22Hamburger％22 ％2C％22quantite％22％3A +％220％22％7D％2C +％7B％22id％22％3A +％222％22％2C％22nom％22％3A +％22Cheeseburger％22％2C％22quantite％22％3A +％220 ％22％7D％2C +％7B％22id％22％3A +％223％22％2C％22nom％22％3A +％22Giant％22％2C％22quantite％22％3A +％220％22％7D％2C +％7B％22id ％22％3A +％224％22％2C％22nom％22％3A +％22Giant + Max。％22％2C％22quantite％22％3A +％220％22％7D％2C +％7B％22id％22％3A +％225％ 22％2C％22nom％22％3A +％22Bacon + Max。％22％2C％22quantite％22％3A +％220％22％7D％2C +％7B％22id％22％3A +％226％22％2C％22nom％22 ％3A +％22Supreme + Cheese％22％2C％22quantite％22％3A +％220％22％7D％2C +％7B％22id％22％3A +％227％22％2C％22nom％22％3A +％22Supreme + Pepper％22 ％2C％22quantite％22％3A +％220％22％7D％2C +％7B％22id％22％3A +％228％22％2C％22nom％22％3A +％22Supreme + Chicken％22％2C％22quantite％22％3A + ％220％22％7D％2C +％7B％22id％22％3A +％229％22％2C％22nom％22％3A +％22Fish + Burger％22％2C％22quantite％22％3A +％220％22％7D％2C + ％7B％22id％22％3A +％2210％22％2C％22nom％22％3A +％22鸡肉+汉堡％22％2C％22quantite％22％3A +％220％22％7D％2C +％7B％22id％22％3A + ％2211％22％2 C％22nom％22％3A +％22Diabolo％22％2C％22quantite％22％3A +％220％22％7D％2C +％7B％22id％22％3A +％2212％22％2C％22nom％22％3A +％22Barbecue％ 22％2C％22quantite％22％3A +％220％22％7D％5D

'''

我检查互联网，当我将其解码为json时得到： JSON DECODE

Answer 1

我有一个错误，因为我正在发送一个非Json数组。在方法doinbackground中，我使用urlEncode，当我检查该功能在做什么时，我读：

将空格字符“”转换为加号“ +”。

这就是为什么当我json_decode file_get_contents（“ php：// input”）时我有一个错误的jsonArray

发送请求到服务器

1 个答案: