从Android到PHP页面的HttpPost请求(参数没有传递)

我的PHP代码:

<?php
$data = 'basic';
if( $_POST["tag"]){
   $data = $data.$_POST['tag'];
}
if( $_GET["tag"]){
   $data = $data.$_GET['tag'];
}
echo $data;
?>

我的Android代码:

String url = http: //<IP>/sreeweb/sample.php;
List params = new ArrayList();
params.add(new BasicNameValuePair("tag", "services"));
InputStream is = null;
try {
   DefaultHttpClient httpClient = new DefaultHttpClient();
   HttpPost httpPost = new HttpPost(url);
   httpPost.setHeader(HTTP.CONTENT_TYPE, "application/x-www-form-urlencoded");
   httpPost.setHeader("Accept", "*/*");
   httpPost.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
   HttpResponse httpResponse = httpClient.execute(httpPost);
   Log.d("msg", "res : " + httpResponse.getStatusLine().getStatusCode()); //200
   HttpEntity httpEntity = httpResponse.getEntity();
   is = httpEntity.getContent();
   Log.d("msg", "" + is);
} catch (UnsupportedEncodingException e) {
   e.printStackTrace();
} catch (ClientProtocolException e) {
   e.printStackTrace();
} catch (IOException e) {
   e.printStackTrace();
}
BufferedReader reader;
StringBuilder stringBuilder = null;
try {
   reader = new BufferedReader(new InputStreamReader(is, "iso-8859-1"), 8);
   stringBuilder = new StringBuilder();
   String line = null;
   while ((line = reader.readLine()) != null) {
      stringBuilder.append(line + "'n");
   }
   is.close();
} catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
}
String result = stringBuilder.toString();
Log.e(TAG, result);

GET方法正在工作。但是POST方法不工作时，我从Android调用它。它正在调用PHP页面，但没有传递值。

但是，当我通过Chrome (Chrome -extension://hgmloofddffdnphfgcellkdfbfbjeloo/RestClient.html)从REST客户端调用POST方法时，它的工作原理和值正在正确传递。但为什么不能从Android平台呢?

我甚至尝试使用以下代码，但它不起作用:

try {
   String data = URLEncoder.encode("tag", "UTF-8") + "=" + URLEncoder.encode("services", "UTF-8");
   URL url = new URL(finalUrl);
   HttpURLConnection conn = null;
   conn = (HttpURLConnection) url.openConnection();
           conn.setRequestProperty("Content-type", "application/x-www-form-urlencoded");
   conn.setRequestProperty("Accept", "*/*");
   // Allow Inputs
   conn.setDoInput(true);
   conn.setDoOutput(true);
   // Use a post method.
   conn.setRequestMethod("POST");
   OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());
   wr.write(data);
   wr.flush();
   BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
   StringBuilder sb = new StringBuilder();
   String line = null;
   // Read Server Response
   while ((line = reader.readLine()) != null) {
      sb.append(line);
      break;
   }
   Log.e(TAG, "postMethod  " + sb.toString());
   return sb.toString();

} catch (Exception e) {
    return new String("Exception: " + e.getMessage());
}