19 Android简单示例
最后更新于：2022-04-01 02:50:25
# Andriod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](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](http://lukencode.com/2010/04/27/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。