如何從 Android 發出 http 請求？

Question

我正在嘗試制作一個移動應用程序，我目前正在創建 api 用於與服務器通信。 我的代碼在正常的 maven 項目上工作正常，但是當我將它添加到我的 android 工作室項目時，當我嘗試從連接輸入 stream 讀取時出現錯誤。

package client;

import org.json.JSONObject;

import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;

public class CCH {

    //static private String host = "http://localhost:8080";
    static private String host ="https://radiant-bayou-97811.herokuapp.com";

    //GET REQUESTS
    public static Integer login(String username, String password){
        String tempurl = host + "/api/user/login/" + username + "/" + password;
        JSONObject jsonObject = getRequest(tempurl);
        if(jsonObject.has("login"))
            if(jsonObject.get("login").equals("true"))
                return 1;
            else
                return 0;
        else
            return 0;
    }
    public static JSONObject getPacient(String username){
        String tempurl = host + "/api/user/getPacient/" + username;
        return getRequest(tempurl);
    }
    public static JSONObject getIstoric(String username){
        String tempurl = host + "/api/user/pacient/istoric/" + username;
        return getRequest(tempurl);
    }
    public static JSONObject getDiagnostic(String username){
        String tempurl = host + "/api/user/pacient/diagnostic/" + username;
        return getRequest(tempurl);
    }
    //POST REQUESTS
    public static void sendData(String username,String time,String puls,String calorii,String nr_pasi,String nivel_oxigen,String calitate_somn){
        String tempurl = host+ "/api/user/pacient/importData";
        JSONObject jsonObject = new JSONObject();
        jsonObject.append("username",username);
        jsonObject.append("time",time);
        jsonObject.append("puls",puls);
        jsonObject.append("calorii",calorii);
        jsonObject.append("nr_pasi",nr_pasi);
        jsonObject.append("nivel_oxigen",nivel_oxigen);
        jsonObject.append("calitate_somn",calitate_somn);

        postRequest(tempurl,jsonObject);
    }
    public static JSONObject getRequest(String URL){
        JSONObject response = null;
        HttpURLConnection connection = null;
        try {



            URL url = new URL(URL);

            connection = (HttpURLConnection) url.openConnection();

            connection.setRequestMethod("GET");

            response = new JSONObject(readFromConnection(connection));




        }catch (Exception e){
            response = new JSONObject();
            response.append("Error!","Error on the client side contact the admin!");
            response.append("Error!!",e.getCause());
            e.printStackTrace();
        }
        finally {
            connection.disconnect();
            return response;
        }
    }
    public static void postRequest(String URL,JSONObject jsonObject){
        HttpURLConnection connection = null;
        try{
            URL url = new URL(URL);

            connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("POST");
            connection.setRequestProperty("Content-Type", "application/json");
//            connection.setRequestProperty("Accept", "application/json");

            connection.setDoOutput(true);

            OutputStream os = connection.getOutputStream();
            os.write(createJson(jsonObject).getBytes());
            System.out.println(createJson(jsonObject));
            os.flush();
            os.close();
            int responseCode = connection.getResponseCode();
        } catch (Exception e){
            System.out.println("Unable to make post request!");
            System.out.println(e.getCause());
            System.out.println(e.getStackTrace());
            System.out.println(URL);
        }
    }
    public static String readFromConnection(HttpURLConnection connection) throws IOException {
        StringBuilder content;
        BufferedReader input = new BufferedReader(new InputStreamReader(connection.getInputStream()));
        String line;
        content = new StringBuilder();
        while ((line = input.readLine()) != null) {
            content.append(line);
        }
        return content.toString();
    }
    public static String createJson(JSONObject jsonObject){
            StringBuilder tempString = new StringBuilder();
            tempString.append("{");
            int count = 0;
            for(String key : jsonObject.keySet()){
                if(count!=0)
                    tempString.append(",");
                tempString.append("\"");
                tempString.append(key);
                tempString.append("\"");
                tempString.append(":");
                String temp = jsonObject.get(key).toString();
                temp = temp.substring(1);
                temp = temp.substring(0,temp.length()-2);
                tempString.append(temp);
                tempString.append("\"");
                count++;
            }
            tempString.delete(tempString.length()-1,tempString.length()-1);
            tempString.append("}");
            return tempString.toString();
    }
}

我也嘗試過使用 AsyncTask 但我無法讓它工作。

public class LoginAsync extends AsyncTask<URL, Integer, Long> {
    protected Long doInBackground(URL... urls) {

        String tempurl = "https://radiant-bayou-97811.herokuapp.com" + "/api/user/login/" + "user" + "/" + "test";
        JSONObject jsonObject = getRequest(tempurl);
        System.out.println(jsonObject);
        System.out.println(tempurl);

        if (jsonObject.has("login")) {
            try {
                if (jsonObject.get("login").equals("true"))
                    return 1L;
                else
                    return 0L;
            } catch (JSONException e) {
                e.printStackTrace();
            }
        }
        else
            return 0L;
        return 0L;
    }

    protected void onProgressUpdate(Integer... progress) {
    }

    protected void onPostExecute(String result) {
          System.out.println("something");
        }

然后我只是用一些隨機的 url 調用 LoginAsync。 我不明白我做錯了什么。

Answer 1

工作正常......無論如何......但不是...... Android ...

如果僅在 Android 設備（或來自 Android Studio IDE 的模擬設備）上運行代碼時發生錯誤，則這暗示您的 android 權限設置可能丟失...

您是否已將<user-permission android:name="android.permission.INTERNET" />添加到您的 AndroidManifest.xml 中？