使用HttpURLConnection從Android發送HTTP POST

Question

我試圖將Android應用程序的HTTP POST請求發送到我的PHP編碼服務器，該編碼服務器將從請求收到的數據置於MySQL數據庫中。如果我使用HttpClient和HttpPost方法來做，一切正常，但我決定嘗試HttpURLConnection類，因爲它被認爲比舊的HttpClient和HttpPost類更優化和更新，並且不幸的是，我無法獲得它以這種方式工作。我沒有收到任何錯誤或異常，並且設備正在連接到網絡，但沒有任何反應，給定的值未寫入數據庫。請告訴我我做錯了什麼，並建議我。也許最好使用HttpClient/HttpPost方法？

這是我的代碼：

private void writeToDatabase(URL url, String number, String comment) throws IOException { 
     HttpURLConnection httpConnection = (HttpURLConnection) url.openConnection(); 
     httpConnection.setConnectTimeout(15 * 1000); 
     httpConnection.setReadTimeout(10 * 1000); 
     httpConnection.setRequestMethod("POST"); 
     httpConnection.setDoInput(true); 
     httpConnection.setDoOutput(true); 

     List<NameValuePair> params = new ArrayList<NameValuePair>(3); 
     params.add(new BasicNameValuePair("code", "****")); 
     params.add(new BasicNameValuePair("number", number)); 
     params.add(new BasicNameValuePair("comment", comment)); 

     OutputStream os = httpConnection.getOutputStream(); 
     BufferedWriter br = new BufferedWriter(new OutputStreamWriter(os, "UTF-8")); 
     br.write(getQuery(params)); 
     br.flush(); 
     br.close(); 
     os.close(); 

     httpConnection.connect(); 
} 

getQuery()功能：

private String getQuery(List<NameValuePair> params) throws UnsupportedEncodingException { 
     StringBuilder result = new StringBuilder(); 
     boolean first = true; 

     for (NameValuePair pair : params) { 
      if (first) { 
       first = false; 
      } else result.append("&"); 

      result.append(URLEncoder.encode(pair.getName(), "UTF-8")); 
      result.append("="); 
      result.append(URLEncoder.encode(pair.getValue(), "UTF-8")); 
     } 

     return result.toString(); 
} 

這是如何以及在何處我所說的writeToDatabase()功能：

Thread thread = new Thread() { 

    @Override 
    public void run() { 
     try { 
      URL url = new URL("http://www.***.com"); 
      writeToDatabase(url, "****", "as pats"); 
     } catch (MalformedURLException e) { 
      e.printStackTrace(); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 
    } 
}; 
thread.start(); 

編輯：這是SOO怪異...閱讀以下代碼片段中的註釋：

private void writeToDatabase(URL url, String number, String comment) throws IOException { 
     HttpURLConnection httpConnection = (HttpURLConnection) url.openConnection(); 
     httpConnection.setConnectTimeout(15 * 1000); 
     httpConnection.setReadTimeout(10 * 1000); 
     httpConnection.setRequestMethod("POST"); 
     httpConnection.setDoInput(true); 
     httpConnection.setDoOutput(true); 

     httpConnection.connect(); 

     List<NameValuePair> params = new ArrayList<NameValuePair>(3); 
     params.add(new BasicNameValuePair("code", "****")); 
     params.add(new BasicNameValuePair("number", number)); 
     params.add(new BasicNameValuePair("comment", comment)); 

     OutputStream os = httpConnection.getOutputStream(); 
     BufferedWriter br = new BufferedWriter(new OutputStreamWriter(os, "UTF-8")); 
     br.write(getQuery(params)); 
     br.flush(); 
     br.close(); 
     os.close(); 
     //Everything works just fine with these lines below, but without them, it doesn't work... Why is that? 
     BufferedReader in = new BufferedReader(new InputStreamReader(httpConnection.getInputStream())); 
     String inputLine; 
     while ((inputLine = in.readLine()) != null) { 
      Log.i("ilog", inputLine); 
     } 

     httpConnection.disconnect(); 
} 

它看起來像爲什麼這段代碼不起作用的問題是我沒有閱讀響應。如果我讀到這樣的回答：

BufferedReader in = new BufferedReader(new InputStreamReader(httpConnection.getInputStream())); 
     String inputLine; 
     while ((inputLine = in.readLine()) != null) { 
      Log.i("ilog", inputLine); 
     } 

然後，一切正常完美。但爲什麼呢？有人可以向我解釋這一點嗎？我非常感興趣！

編輯2：即使我設置了httpConnection.setDoOutput(false);只要我讀到響應，它仍然可以正常工作。即使setDoOutput()設置爲false，也會將值寫入數據庫。我完全糊塗了......

Answer 1

這個例子顯示connect（）第一次，將POST數據寫入輸出流，檢查響應代碼，關閉輸出流。

http://soda815.blogspot.com/2013/09/android-how-to-use-httpurlconnection-to.html

Answer 2

我同意Salivan。在不檢查響應代碼的情況下，在POST發送到服務器之前，tcp連接將被重置。但沒有人討論過這一點。有什麼理由嗎？

if (conn.getResponseCode() == HttpURLConnection.HTTP_OK) { 
       inputStream = conn.getInputStream(); 
      }