使用HttpURLConnection從Android發送HTTP POST

Question

我正在嘗試從Android應用程序向我的PHP編碼服務器發送HTTP POST請求，該服務器將從請求接收的數據放入MySQL數據庫。 如果我使用HttpClient和HttpPost方法做到這一點，一切正常，但我決定嘗試HttpURLConnection類，因為它被認為比舊的HttpClient和HttpPost類更優化和更新，並且，不幸的是，我無法得到它以這種方式工作。 我沒有收到任何錯誤或異常，設備正在連接到網絡，但沒有任何反應，給定的值不會寫入數據庫。 請告訴我我做錯了什么並給我建議。 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()函數：

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();
}

這就是我調用writeToDatabase()函數的方式和位置：

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：那太酷了...閱讀以下代碼片段中的注釋：

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();
}

看起來這個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);
        }

然后一切都很完美。 但為什么呢？ 有人可以向我解釋一下嗎？ 我很感興趣！

編輯2：即使我設置了httpConnection.setDoOutput(false); 只要我閱讀回復，它仍然可以完美運行。 即使setDoOutput()設置為false也會將值寫入數據庫。 我完全糊塗了......

Answer 1

此示例首先顯示connect（），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的觀點。 在不檢查響應代碼的情況下，在將POST發送到服務器之前，將重置tcp連接。 但沒人討論這個問題。 有什么緣故嗎？

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