Android网络编程之Http通信
Android中提供的HttpURLConnection和HttpClient接口可以用来开发HTTP程序。以下是本人在学习中的总结与归纳。
1. HttpURLConnection接口首先需要明确的是,Http通信中的POST和GET请求方式的不同。GET可以获得静态页面,也可以把参数放在URL字符串后面,传递给服务器。而POST方法的参数是放在Http请求中。因此,在编程之前,应当首先明确使用的请求方法,然后再根据所使用的方式选择相应的编程方式。
HttpURLConnection是继承于URLConnection类,二者都是抽象类。其对象主要通过URL的openConnection方法获得。创建方法如下代码所示:
1 | URL url = new URL( "http://www.51cto.com/index.jsp?par=123456" ); |
2 | HttpURLConnection urlConn=(HttpURLConnection)url.openConnection(); |
通过以下方法可以对请求的属性进行一些设置,如下所示:
2 | urlConn.setDoOutput( true ); |
3 | urlConn.setDoInput( true ); |
5 | urlConn.setRequestMethod( "POST" ); |
7 | urlConn.setUseCaches( false ); |
9 | urlConn.disConnection(); |
HttpURLConnection默认使用GET方式,例如下面代码所示:
01 | //使用HttpURLConnection打开连接 |
02 | HttpURLConnection urlConn = (HttpURLConnection)url.openConnection(); |
04 | InputStreamReader in = new InputStreamReader(urlConn.getInputStream()); |
06 | BufferedReader buffer = new BufferedReader(in); |
07 | String inputLine = null ; |
09 | while (((inputLine = buffer.readLine())!= null )) |
12 | resultData += inputLine + "\n" ; |
如果需要使用POST方式,则需要setRequestMethod设置。代码如下:
01 | String httpUrl = "http://192.168.1.110:8080/httpget.jsp" ; |
08 | url = new URL(httpUrl); |
10 | catch (MalformedURLException e) |
12 | Log.e(DEBUG_TAG, "MalformedURLException" ); |
18 | // 使用HttpURLConnection打开连接 |
19 | HttpURLConnection urlConn = (HttpURLConnection)url.openConnection(); |
20 | //因为这个是post请求,设立需要设置为true |
21 | urlConn.setDoOutput( true ); |
22 | urlConn.setDoInput( true ); |
24 | urlConn.setRequestMethod( "POST" ); |
26 | urlConn.setUseCaches( false ); |
27 | urlConn.setInstanceFollowRedirects( true ); |
28 | // 配置本次连接的Content-type,配置为application/x-www-form-urlencoded的 |
29 | urlConn.setRequestProperty( "Content-Type" , "application/x-www-form-urlencoded" ); |
30 | // 连接,从postUrl.openConnection()至此的配置必须要在connect之前完成, |
31 | // 要注意的是connection.getOutputStream会隐含的进行connect。 |
34 | DataOutputStream out = new DataOutputStream(urlConn.getOutputStream()); |
36 | String content = "par=" + URLEncoder.encode( "ABCDEFG" , "gb2312" ); |
38 | out.writeBytes(content); |
2. HttpClient接口
使用Apache提供的HttpClient接口同样可以进行HTTP操作。
对于GET和POST请求方法的操作有所不同。GET方法的操作代码示例如下:
02 | String httpUrl = "http://192.168.1.110:8080/httpget.jsp?par=HttpClient_android_Get" ; |
04 | HttpGet httpRequest = new HttpGet(httpUrl); |
06 | HttpClient httpclient = new DefaultHttpClient(); |
07 | //请求HttpClient,取得HttpResponse |
08 | HttpResponse httpResponse = httpclient.execute(httpRequest); |
10 | if (httpResponse.getStatusLine().getStatusCode()== HttpStatus.SC_OK) |
13 | String strResult = EntityUtils.toString(httpResponse.getEntity()); |
14 | mTextView.setText(strResult); |
18 | mTextView.setText( "请求错误!" ); |
使用POST方法进行参数传递时,需要使用NameValuePair来保存要传递的参数。,另外,还需要设置所使用的字符集。代码如下所示:
02 | String httpUrl = "http://192.168.1.110:8080/httpget.jsp" ; |
04 | HttpPost httpRequest = new HttpPost(httpUrl); |
05 | //使用NameValuePair来保存要传递的Post参数 |
06 | List<NameValuePair>params = new ArrayList<NameValuePair>(); |
08 | params.add( new BasicNameValuePair( "par" , "HttpClient_android_Post" )); |
10 | HttpEntity httpentity = new UrlEncodedFormEntity(params, "gb2312" ); |
12 | httpRequest.setEntity(httpentity); |
14 | HttpClient httpclient = new DefaultHttpClient(); |
16 | HttpResponse httpResponse = httpclient.execute(httpRequest); |
17 | //HttpStatus.SC_OK表示连接成功 |
18 | if (httpResponse.getStatusLine().getStatusCode()== HttpStatus.SC_OK) |
21 | String strResult = EntityUtils.toString(httpResponse.getEntity()); |
22 | mTextView.setText(strResult); |
26 | mTextView.setText( "请求错误!" ); |
HttpClient实际上是对Java提供方法的一些封装,在HttpURLConnection中的输入输出流操作,在这个接口中被统一封装成了HttpPost(HttpGet)和HttpResponse,这样,就减少了操作的繁琐性。
另外,在使用POST方式进行传输时,需要进行字符编码