19 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

public void Execute(RequestMethod method) throws Exception {
    switch (method) {
    case GET: {
        // add parameters
        String combinedParams = "";
        if (!params.isEmpty()) {
            combinedParams += "?";
            for (NameValuePair p : params) {
                String paramString = p.getName() + "="
                        + URLEncoder.encode(p.getValue(), HTTP.UTF_8);
                if (combinedParams.length() > 1) {
                    combinedParams += "&" + paramString;
                } else {
                    combinedParams += paramString;
                }
            }
        }
        HttpGet request = new HttpGet(url + combinedParams);
        request.addHeader("Accept-Encoding", "gzip");
        // add headers
        for (NameValuePair h : headers) {
            request.addHeader(h.getName(), h.getValue());
        }
        executeRequest(request, url);
        break;
    }
    case POST: {
        HttpPost request = new HttpPost(url);
        request.addHeader("Accept-Encoding", "gzip");
        // add headers
        for (NameValuePair h : headers) {
            request.addHeader(h.getName(), h.getValue());
        }
        if (!data.equals("")) {
            request.setEntity(new StringEntity(data, HTTP.UTF_8));
        }
        if (!params.isEmpty()) {
            request.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
        }
        executeRequest(request, url);
        break;
    }
    case PUT: {
        HttpPut request = new HttpPut(url);
        request.addHeader("Accept-Encoding", "gzip");
        // add headers
        for (NameValuePair h : headers) {
            request.addHeader(h.getName(), h.getValue());
        }
        if (!data.equals("")) {
            request.setEntity(new StringEntity(data, HTTP.UTF_8));
        }
        if (!params.isEmpty()) {
            request.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
        }
        executeRequest(request, url);
        break;
    }
    case DELETE: {
        HttpDelete request = new HttpDelete(url);
        request.addHeader("Accept-Encoding", "gzip");
        // add headers
        for (NameValuePair h : headers) {
            request.addHeader(h.getName(), h.getValue());
        }
        executeRequest(request, url);
        break;
    }
    }
}

这四个方法最后都执行executeRequest来获取响应结果。

protected void executeRequest(HttpUriRequest request, String url) {
        HttpParams httpParameters = new BasicHttpParams();
        HttpConnectionParams.setConnectionTimeout(httpParameters,
                timeoutConnection);
        HttpConnectionParams.setSoTimeout(httpParameters, timeoutSocket);
        HttpProtocolParams.setUseExpectContinue(httpParameters, false);
        request.setParams(httpParameters);
        setOauth(request);
        DefaultHttpClient client = new DefaultHttpClient();
        HttpResponse httpResponse;
        try {
            httpResponse = client.execute(request);
            responseCode = httpResponse.getStatusLine().getStatusCode();
            message = httpResponse.getStatusLine().getReasonPhrase();
            HttpEntity entity = httpResponse.getEntity();
            if (entity != null) {
                InputStream instream = httpResponse.getEntity().getContent();
                Header contentEncoding = httpResponse
                        .getFirstHeader("Content-Encoding");
                if (contentEncoding != null
                        && contentEncoding.getValue().equalsIgnoreCase("gzip")) {
                    instream = new GZIPInputStream(instream);
                }
                // instream = entity.getContent();
                response = convertStreamToString(instream);
                // Closing the input stream will trigger connection release
                instream.close();
            }
        } catch (ClientProtocolException e) {
            client.getConnectionManager().shutdown();
            e.printStackTrace();
        } catch (IOException e) {
            client.getConnectionManager().shutdown();
            e.printStackTrace();
        }
    }

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

RestClient client = new RestClient(tUrl);
try {
    client.Execute(RequestMethod.GET);
    if (client.getResponseCode() != 200) {
        //do something
    }
    //JSONArray jArray = new JSONArray(client.getResponse());
} catch (Exception e) {
    //do something
}

而这时，我们只需要对相应的数据进行处理就可以了，如

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

将他转换为String，接着在Android端上显示最后的结果。