使用HttpURLConnection从Android发送HTTP POST

Question

我试图将Android应用程序的HTTP POST请求发送到我的PHP编码服务器，该编码服务器将从请求收到的数据置于MySQL数据库中。如果我使用HttpClient和HttpPost方法来做，一切正常，但我决定尝试HttpURLConnection类，因为它被认为比旧的HttpClient和HttpPost类更优化和更新，并且不幸的是，我无法获得它以这种方式工作。我没有收到任何错误或异常，并且设备正在连接到网络，但没有任何反应，给定的值未写入数据库。请告诉我我做错了什么，并建议我。也许最好使用HttpClient/HttpPost方法？

这是我的代码：

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(); 
} 

这是如何以及在何处我所说的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(); 

编辑：这是SOO怪异...阅读以下代码片段中的注释：

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(); 
} 

它看起来像为什么这段代码不起作用的问题是我没有阅读响应。如果我读到这样的回答：

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

然后，一切正常完美。但为什么呢？有人可以向我解释这一点吗？我非常感兴趣！

编辑2：即使我设置了httpConnection.setDoOutput(false);只要我读到响应，它仍然可以正常工作。即使setDoOutput()设置为false，也会将值写入数据库。我完全糊涂了......

Answer 1

这个例子显示connect（）第一次，将POST数据写入输出流，检查响应代码，关闭输出流。

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

Answer 2

我同意Salivan。在不检查响应代码的情况下，在POST发送到服务器之前，tcp连接将被重置。但没有人讨论过这一点。有什么理由吗？

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