Android简单示例

由于在某些嵌入式系统中使用的是Android系统，这里给出一个简单的Android App的示例，具体代码可以从clone自https://github.com/phodal/iot-android

代码说明，经过测试的版本有

  • Android 2.3
  • Android 4.0.4

机型有

  • HTC G1 (android 2.3)
  • Motor xt300 (android 2.3)
  • Sony ST25I (android 4.0.4)
  • MI2

应该可以在大部分的手机上工作。

调用Web Services GET

这里我们参考一篇文章来调用Web Services——Calling Web Services in Android using HttpClient

创建RESTClient

在这里我们首先会定义四个REST方法GET、POST、PUT、DELETE

  1. public void Execute(RequestMethod method) throws Exception {
  2.     switch (method) {
  3.     case GET: {
  4.         // add parameters
  5.         String combinedParams = "";
  6.         if (!params.isEmpty()) {
  7.             combinedParams += "?";
  8.             for (NameValuePair p : params) {
  9.                 String paramString = p.getName() + "="
  10.                         + URLEncoder.encode(p.getValue(), HTTP.UTF_8);
  11.                 if (combinedParams.length() > 1) {
  12.                     combinedParams += "&" + paramString;
  13.                 } else {
  14.                     combinedParams += paramString;
  15.                 }
  16.             }
  17.         }
  19.         HttpGet request = new HttpGet(url + combinedParams);
  20.         request.addHeader("Accept-Encoding", "gzip");
  22.         // add headers
  23.         for (NameValuePair h : headers) {
  24.             request.addHeader(h.getName(), h.getValue());
  25.         }
  27.         executeRequest(request, url);
  28.         break;
  29.     }
  30.     case POST: {
  31.         HttpPost request = new HttpPost(url);
  32.         request.addHeader("Accept-Encoding", "gzip");
  34.         // add headers
  35.         for (NameValuePair h : headers) {
  36.             request.addHeader(h.getName(), h.getValue());
  37.         }
  38.         if (!data.equals("")) {
  39.             request.setEntity(new StringEntity(data, HTTP.UTF_8));
  40.         }
  42.         if (!params.isEmpty()) {
  43.             request.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
  44.         }
  46.         executeRequest(request, url);
  47.         break;
  48.     }
  49.     case PUT: {
  50.         HttpPut request = new HttpPut(url);
  51.         request.addHeader("Accept-Encoding", "gzip");
  53.         // add headers
  54.         for (NameValuePair h : headers) {
  55.             request.addHeader(h.getName(), h.getValue());
  56.         }
  57.         if (!data.equals("")) {
  58.             request.setEntity(new StringEntity(data, HTTP.UTF_8));
  59.         }
  61.         if (!params.isEmpty()) {
  62.             request.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
  63.         }
  65.         executeRequest(request, url);
  66.         break;
  67.     }
  68.     case DELETE: {
  69.         HttpDelete request = new HttpDelete(url);
  70.         request.addHeader("Accept-Encoding", "gzip");
  72.         // add headers
  73.         for (NameValuePair h : headers) {
  74.             request.addHeader(h.getName(), h.getValue());
  75.         }
  77.         executeRequest(request, url);
  78.         break;
  79.     }
  80.     }
  81. }

这四个方法最后都执行executeRequest来获取响应结果。

  1. protected void executeRequest(HttpUriRequest request, String url) {
  3.         HttpParams httpParameters = new BasicHttpParams();
  4.         HttpConnectionParams.setConnectionTimeout(httpParameters,
  5.                 timeoutConnection);
  6.         HttpConnectionParams.setSoTimeout(httpParameters, timeoutSocket);
  8.         HttpProtocolParams.setUseExpectContinue(httpParameters, false);
  9.         request.setParams(httpParameters);
  11.         setOauth(request);
  13.         DefaultHttpClient client = new DefaultHttpClient();
  15.         HttpResponse httpResponse;
  17.         try {
  18.             httpResponse = client.execute(request);
  19.             responseCode = httpResponse.getStatusLine().getStatusCode();
  20.             message = httpResponse.getStatusLine().getReasonPhrase();
  22.             HttpEntity entity = httpResponse.getEntity();
  24.             if (entity != null) {
  25.                 InputStream instream = httpResponse.getEntity().getContent();
  26.                 Header contentEncoding = httpResponse
  27.                         .getFirstHeader("Content-Encoding");
  29.                 if (contentEncoding != null
  30.                         && contentEncoding.getValue().equalsIgnoreCase("gzip")) {
  31.                     instream = new GZIPInputStream(instream);
  32.                 }
  34.                 // instream = entity.getContent();
  35.                 response = convertStreamToString(instream);
  37.                 // Closing the input stream will trigger connection release
  38.                 instream.close();
  39.             }
  41.         } catch (ClientProtocolException e) {
  42.             client.getConnectionManager().shutdown();
  43.             e.printStackTrace();
  44.         } catch (IOException e) {
  45.             client.getConnectionManager().shutdown();
  46.             e.printStackTrace();
  47.         }
  48.     }

接着，我们便可以执行getResponse()函数来获取结果。

使用REST Client获取结果

使用RESTClient时，便可以用下面的示例

  1. RestClient client = new RestClient(tUrl);
  2. try {
  3.     client.Execute(RequestMethod.GET);
  4.     if (client.getResponseCode() != 200) {
  5.         //do something
  6.     }
  7.     //JSONArray jArray = new JSONArray(client.getResponse());
  8. } catch (Exception e) {
  9.     //do something
  10. }

而这时，我们只需要对相应的数据进行处理就可以了，如

  1. JSONArray jArray = new JSONArray(client.getResponse());
  2. JSONObject jObj=jArray.getJSONObject(0);
  3. vshow.setText(jObj.toString());
  5. outputJSON(jObj);

将他转换为String，接着在Android端上显示最后的结果。