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Android学习笔记:利用httpclient和AsyncTask 发起网络http post操作

1、在android4中,发起网络http操作,不能在Activity的事件(即主线程)中进行,必须在单独的线程中操作。

另外进行网络操作,需要在manifest文件中增加如下的权限:

<uses-permission android:name="android.permission.INTERNET" />

2、下面给出代码事例

	public void loadData() {		new AsyncTask<String, Void, String>() {			@Override			protected String doInBackground(String... paramsInput) {				String url = "http://10.0.0.5:8080/examples/action";				List<NameValuePair> params = new ArrayList<NameValuePair>();				params.add(new BasicNameValuePair("type", paramsInput[0]));				params.add(new BasicNameValuePair("id", paramsInput[1]));				/* 建立HTTPPost对象 */				HttpPost httpRequest = new HttpPost(url);				String strResult = "doPostError";				try {					HttpClient httpClient = getHttpClient();					/* 添加请求参数到请求对象 */					httpRequest.setEntity(new UrlEncodedFormEntity(params,							HTTP.UTF_8));					/* 发送请求并等待响应 */					HttpResponse httpResponse = httpClient.execute(httpRequest);					/* 若状态码为200 ok */					if (httpResponse.getStatusLine().getStatusCode() == 200) {						/* 读返回数据 */						strResult = EntityUtils.toString(httpResponse								.getEntity());					} else {						strResult = "Error Response: "								+ httpResponse.getStatusLine().toString();					}				} catch (ClientProtocolException e) {					strResult = "Error Response: " + e.getMessage().toString();					e.printStackTrace();				} catch (IOException e) {					strResult = "Error Response: " + e.getMessage().toString();					e.printStackTrace();				} catch (Exception e) {					strResult = "Error Response: " + e.getMessage().toString();					e.printStackTrace();				}				return strResult;			}			@Override			protected void onPostExecute(String result) {				TextView view = (TextView) findViewById(R.id.resultText);				view.setText(result);				super.onPostExecute(result);			}		}.execute("query","1");	}private HttpClient getHttpClient() {		// 创建 HttpParams 以用来设置 HTTP 参数(这一部分不是必需的)		HttpParams httpParams = new BasicHttpParams();		// 设置连接超时和 Socket 超时,以及 Socket 缓存大小		HttpConnectionParams.setConnectionTimeout(httpParams, 20 * 1000);		HttpConnectionParams.setSoTimeout(httpParams, 20 * 1000);		HttpConnectionParams.setSocketBufferSize(httpParams, 8192);		// 设置重定向,缺省为 true		HttpClientParams.setRedirecting(httpParams, true);		// 设置 user agent		String userAgent = "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9.2) Gecko/20100115 Firefox/3.6";		HttpProtocolParams.setUserAgent(httpParams, userAgent);		// 创建一个 HttpClient 实例		// 注意 HttpClient httpClient = new HttpClient(); 是Commons HttpClient		// 中的用法,在 Android 1.5 中我们需要使用 Apache 的缺省实现 DefaultHttpClient		HttpClient httpClient = new DefaultHttpClient(httpParams);		return httpClient;	}

 上述代码的loadData方法中,创建一个AsyncTask对象,在对象的doInBackground方法中发起网络操作,获取到操作结果。然后在onPostExecute方法中,利用前面获取到的结果更新界面。

   这里的网络操作主要是利用了HttpClient等相关api,位于org.apache.http.client.HttpClient下。

 

Android学习笔记:利用httpclient和AsyncTask 发起网络http post操作