如何將所有的SQL表數據插入到java中的數組[android studio]

Question

我想要獲取我的sql服務器表中的所有數據並將其插入到數組中。

我的表的名稱是「用戶」，我想所有的名字和電子郵件，並把 他們的陣列喜歡裏面：

[姓名，電子郵件，姓名，郵箱，姓名，電子郵件。 .....]

我用排列雖然將數據發佈到我的sql服務器，但我無法獲得任何數據。 這是第代碼我寫，我不知道如何去完成它：

private static Array GetData() { 

    StringRequest strReq = new StringRequest(Method.POST, 
      AppConfig.URL_GETDATA, new Response.Listener<String>() { // URL_LOGIN is the php file which will extract the data 

     ...... 

Answer 1

差不多一步一步來。

你需要爲你的web服務的PHP代碼可能是這樣的：

<?php 

/* 
* Following code will get single User's details 
* using the Student ID number 
*/ 

// array for JSON response 
$response = array(); 

// check for post data 
if (isset($_POST['param1']) && 
    isset($_POST['param2']) && 
    isset($_POST['param3'])) { 

    $param1 = $_POST['param1']; 
    $param2 = $_POST['param2']; 
    $param3 = $_POST['param3']; 

    // include db connect class 
    require_once __DIR__ . '/db_config.php'; 
    // set vars 
    $host = DB_SERVER; 
    $db = DB_DATABASE; 
    $user = DB_USER; 
    $pass = DB_PASSWORD; 
    $charset = 'utf8'; 

    $dsn = "mysql:host=$host;dbname=$db;charset=$charset"; 
    $opt = [ 
     PDO::ATTR_ERRMODE   => PDO::ERRMODE_EXCEPTION, 
     PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC, 
     PDO::ATTR_EMULATE_PREPARES => false, 
    ]; 

    // connecting to db 
    $pdo = new PDO($dsn, $user, $pass, $opt); 

    $sql = 'SELECT * FROM tblYourTable 
      WHERE ID = :id_STM 
      AND col2 >= :col2_STM 
      AND col3 >= :col3_STM 
      '; 
    $stmt = $pdo->prepare($sql); 
    $stmt->bindParam(':id_STM', $param1, PDO::PARAM_INT); 
    $stmt->bindParam(':col2_STM', $param2, PDO::PARAM_STR); // this could be a string parameter 
    $stmt->bindParam(':col3_STM', $param3, PDO::PARAM_STR); // oddly, Doubles are given as STR also!! 

    $res = $stmt->execute(); 

    /* Check the number of rows that match the SELECT statement */ 
    if ($res) { 
     // success 
     $response["success"] = 1; 
     // connection node 
     $response["data"] = array(); 

     // This will retreive as many rows as your query has aquired 
     while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) { 
      $data = array(); // Your return array 
      $data["data1"] = $row["Col1"]; 
      $data["data2"] = $row["Col2"]; 
      $data["data3"] = $row["Col3"]; 
      // ... and so on til you have all the data you need 
      $data["data_N"] = $row["Col_N"]; 

      // pushes a new row onto your array with each iteration 
      array_push($response["data"], $data); 
     } 
    } 
    else { 
     /* No rows matched -- do something else */ 
     // required field is missing 
     $response["success"] = 0; 
     $response["message"] = "No data returned!!"; 

    } 
} 
else { 
    $response["success"] = 0; 
    $response["message"] = "Parameters are not correct"; 
} 
// echoing JSON response 
echo json_encode($response); 
?> 

加入您的數據庫連接數據在一個單獨的文件。

數據庫查詢可能類似於此：

public String selectYourData(int id, String param2, double param2){ 
    String res = ""; 
    try { 

     // add parameters to list which need to match the parameters in your PHP code 
     Map<String, String> params = new LinkedHashMap<String, String>(); 
     params.put("param1", String.valueOf(id)); 
     params.put("param2", String.valueOf(id)); 
     params.put("param3", String.valueOf(id)); 

     // get the json string from the result set from the central database 
     HttpRequestCommand http = new HttpRequestCommand(); 
     // the return is a json string containing the url of the    

     res = http.makeHttpRequestJsonString("my_php_script.php", params); 
     JSONObject jObj = new JSONObject(res); 
     String success = jObj.getString("success"); 
     if(success.contentEquals("1")){ 
      //Data downloaded successfully!! 

     } 
     else{ // else maybe do something?? 
      res = "MyWarningFlag" 
     } 
    } 
    catch (Exception ex){ 
     Log.e(TAG, "selectData --- " + ex.getMessage()); 
    } 
    return res; 
} 

但是，爲了讓您的選擇方法來工作，你需要一個HTTP請求，這可能是與此類似：（你將需要投入您自己的主機數據，連接數據，密碼和問題等等來訪問Web服務器）

 private static final String TAG = "YourClassNameHere" 

    public String makeHttpRequestJsonString(String phpScript, Map<String, String> params){ 
     String json = ""; 
     InputStream responseStream = null; 

     String logMess = ""; 
     long startTime; 
     long stopTime; 
     long elapsedTime; 

     // Replace as needed (with subdirectories as needed) 
     String host = "Http://yourWebSite.com/dir1/dir2/"; 
     host =+ "/" + phpScript 

     // I've changed my code here considerable to simplify it 
     // so you will need to check your URL 
     URL url = new URL(host); 

     try { 
      // Added to observe the performance of the download 
      startTime = System.currentTimeMillis(); 

      StringBuilder postData = new StringBuilder(); 
      for(Map.Entry<String, String> param : params.entrySet()){ 
       param.getValue()); 
       if(postData.length() != 0) postData.append('&'); 
       postData.append(URLEncoder.encode(param.getKey(), "UTF-8")); 
       postData.append('='); 
        postData.append(URLEncoder.encode(String.valueOf(param.getValue()), "UTF-8")); 
      } 
postData.toString()); 

      byte[] postDataBytes = postData.toString().getBytes("UTF-8"); 

      HttpURLConnection conn = (HttpURLConnection) url.openConnection(); 

      conn.setUseCaches(false); 
      conn.setDoOutput(true); 
      conn.setRequestMethod("POST"); 
      conn.setRequestProperty("Connection", "Keep-Alive"); 
      conn.setRequestProperty("Cache-Control", "no-cache"); 
      conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); 
      conn.setRequestProperty("Content-Length", String.valueOf(postDataBytes.length)); 

      DataOutputStream request = new DataOutputStream(conn.getOutputStream()); 
      request.write(postDataBytes); 
      request.flush(); 
      //I've heard some people have issues if they close the request -- I have not 
      request.close(); 

      //Check the response code of the server - 
      Integer replyCode = conn.getResponseCode(); 
      logMess += " Reply Code: " + replyCode.toString(); 

      responseStream = new BufferedInputStream(conn.getInputStream()); 
      BufferedReader responseStreamReader = new BufferedReader(new InputStreamReader(responseStream)); 

      stopTime = System.currentTimeMillis(); 
      elapsedTime = stopTime - startTime; 
      logMess += " elapsed Time : " + elapsedTime + " ms"; 

      // I dump this to the error log -- it is easier to see 
      // but in production all unnecessary logging should be removed 
      Log.e(TAG, "makeHttpRequestJsonString --- " + logMess); 
      String line = ""; 
      StringBuilder stringBuilder = new StringBuilder(); 

      while ((line = responseStreamReader.readLine()) != null) { 
       stringBuilder.append(line).append("\n"); 
      } 
      responseStreamReader.close(); 

      json = stringBuilder.toString(); 
     } 
     catch (UnsupportedEncodingException e) { 
      Log.e(TAG, "makeHttpRequestJsonString --- " + e.getMessage()); 
     } catch (IOException e) { 
      Log.e(TAG, "makeHttpRequestJsonString --- " + e.getMessage()); 
     } 
     // You are now returning the JSON encoded string results 
     return json; 
    } 

最後，從你的活動開球搜索從後臺任務：

/** 
* Background Async Task to Load all Data from your HTTP Request 
* */ 
class LoadServerData extends AsyncTask<String, String, String> { 

    @Override 
    protected void onPreExecute() { 
     super.onPreExecute(); 
    } 

    protected String doInBackground(String... args) { 
     String result = ""; 
     int id = 1;      // your table ID value from somewhere 
     string param2 = "someValue"; // your param if you have one 
     double param3 = 1.1d;   // your param if you have one maybe a double value?? 
     try { 
      // call the class where your 'selectYourData' method is 
      ServerData dataServer = new ServerData(YourActivityClassName.this); 
      result = dataServer.selectYourData(id, param2, param3); 
     } 
     catch (Exception ex) { 
      Log.e(TAG, "LoadServerData --- " + ex.getMessage()); 
     } 

     return result; 
    } 

    protected void onPostExecute(String result) { 
     final String value = result; 

     if(result.isEmpty()) { 
      postEmptyList(); 
      return; 
     } 

     // If you have a lot of data you will want to organize it in its own thread 
     // So you won't block the UI thread 
     runOnUiThread(new Runnable() { 
      public void run() { 
       ListData data; // A custom class for holding your data - you will have to do this part 
       Map<String, ListData> emailList = new LinkedHashMap<>(); 

       try { 
        JSONObject object = new JSONObject(value); 
        JSONArray array = object.getJSONArray("YourRootElementInJson"); 

        int len = array.length(); 
        if(len > 0) { 
         for (int i = 0; i < len; i++) { 
          final JSONObject o = array.getJSONObject(i); 
          data = new ListData(); 

          int userId = o.getInt("col1"); 
          data.setUserId(userID); 

          String userName = o.getString("col2"); 
          data.setUserName(userName); 

          String email = o.getString("col3"); 
          data.setUserEmail(email); 

          emailList.put(userName, data); 
         } 
        } 
       } 
       catch (JSONException jex){ 
        Log.e(TAG, " onPostExecute --- " + jex.getMessage()); 
       } 
       doSometingWithData(array); 
      } 
     }); 
    } 
}