編輯:關於Android編程
本系列文章均為A2BGeek原創,轉載務必在明顯處注明:
轉載自A2BGeek的【Android每周專題】系列,原文鏈接:http://blog.csdn.net/a2bgeek/article/details/11580395
本期專題將講解網絡編程。
很多APP或多或少會有一些訪問網絡的功能,比如用戶的登錄,文件的上傳和下載,更新等功能,本期專題將注重實踐,會有大量的代碼,讀者可以直接拷貝使用。
HTTP 協議可能是現在 Internet 上使用得最多、最重要的協議了,在 JDK 的 java.net 包中已經提供了訪問 HTTP 協議的基本功能:HttpURLConnection。HttpURLConnection是java的標准類,HttpURLConnection繼承自URLConnection,可用於向指定網站發送GET請求、POST請求。
在一般情況下,如果只是需要Web站點的某個簡單頁面提交請求並獲取服務器響應,HttpURLConnection完全可以勝任。但在絕大部分情況下,Web站點的網頁可能沒這麼簡單,這些頁面並不是通過一個簡單的URL就可訪問的,可能需要用戶登錄而且具有相應的權限才可訪問該頁面。在這種情況下,就需要涉及Session、Cookie的處理了,如果打算使用HttpURLConnection來處理這些細節,當然也是可能實現的,只是處理起來難度就大了。
為了更好地處理向Web站點請求,包括處理Session、Cookie等細節問題,Apache開源組織提供了一個HttpClient項目,看它的名稱就知道,它是一個簡單的HTTP客戶端(並不是浏覽器),可以用於發送HTTP請求,接收HTTP響應。但不會緩存服務器的響應,不能執行HTML頁面中嵌入的Javascript代碼,也不會對頁面內容進行任何解析、處理。
簡單來說,HttpClient就是一個增強版的HttpURLConnection,HttpURLConnection可以做的事情HttpClient全部可以做;HttpURLConnection沒有提供的有些功能,HttpClient也提供了,但它只是關注於如何發送請求、接收響應,以及管理HTTP連接。這裡說的用戶登錄僅僅是向服務器發送用戶名和密碼,服務器驗證一下,返回一個標志(比如1代表用戶名和密碼正確登錄成功),真正的登錄功能是沒有這麼簡單的,還需要維護Session。在本小節我將通過四種方式編寫登錄代碼,分別是HttpURLConnection的GET方式和POST方式以及HttpClient的GET方式和POST方式,目的是熟悉Android的網絡編程。服務器端我選用了Facebook的開源框架Tornado,服務器端大家可以根據自己的喜好選擇,比如LAMP的經典組合。接下來就直接上代碼了。
public static String HttpURLConnectionGet(String username, String passwd) { String response = "HttpURLConnectionGet "; try { String urlStr = "http://XXX.XXX.XXX.XXX:8888/normalrequest?username=" + username + "&password=" + passwd; URL url = new URL(urlStr); HttpURLConnection urlConnection = (HttpURLConnection) url .openConnection(); InputStream is = urlConnection.getInputStream(); BufferedReader br = new BufferedReader(new InputStreamReader(is)); String readLine = null; while ((readLine = br.readLine()) != null) { response += readLine; } is.close(); br.close(); urlConnection.disconnect(); } catch (MalformedURLException e) { // TODO Auto-generated catch block Log.v("a2bgeek", "MalformedURLException--->" + e.getMessage()); } catch (IOException e) { // TODO Auto-generated catch block Log.v("a2bgeek", "IOException--->" + e.getMessage()); } return response; }我電腦的IP地址就不寫啦,用XXX代替了。
public static String HttpURLConnectionPost(String username, String passwd) { String response = "HttpURLConnectionPost "; try { String urlStr = "http://XXX.XXX.XXX.XXX:8888/normalrequest"; URL url = new URL(urlStr); HttpURLConnection urlConnection = (HttpURLConnection) url .openConnection(); urlConnection.setDoInput(true); urlConnection.setDoOutput(true); urlConnection.setRequestMethod("POST"); urlConnection.setUseCaches(false); urlConnection.connect(); DataOutputStream out = new DataOutputStream( urlConnection.getOutputStream()); String content = "username=" + username + "&password=" + passwd; out.writeBytes(content); out.flush(); out.close(); InputStream is = urlConnection.getInputStream(); BufferedReader br = new BufferedReader(new InputStreamReader(is)); String readLine = null; while ((readLine = br.readLine()) != null) { response += readLine; } is.close(); br.close(); urlConnection.disconnect(); } catch (MalformedURLException e) { // TODO Auto-generated catch block Log.v("a2bgeek", "MalformedURLException--->" + e.getMessage()); } catch (IOException e) { // TODO Auto-generated catch block Log.v("a2bgeek", "IOException--->" + e.getMessage()); } return response; }
public static String HttpClientGet(String username, String passwd) { String response = "HttpClientGet "; try { String urlStr = "http://XXX.XXX.XXX.XXX:8888/normalrequest?username=" + username + "&password=" + passwd; HttpGet httpGet = new HttpGet(urlStr); HttpClient httpClient = new DefaultHttpClient(); HttpResponse httpResponse = httpClient.execute(httpGet); if (httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) { response += EntityUtils.toString(httpResponse.getEntity()); } } catch (ClientProtocolException e) { // TODO Auto-generated catch block Log.v("a2bgeek", "ClientProtocolException--->" + e.getMessage()); } catch (IOException e) { // TODO Auto-generated catch block Log.v("a2bgeek", "IOException--->" + e.getMessage()); } return response; }
public static String HttpClientPost(String username, String passwd) { String response = "HttpClientPost "; try { String urlStr = "http://XXX.XXX.XXX.XXX:8888/normalrequest"; HttpPost httpPost = new HttpPost(urlStr); Listparams = new ArrayList (); params.add(new BasicNameValuePair("username", username)); params.add(new BasicNameValuePair("password", passwd)); HttpEntity httpEntity = new UrlEncodedFormEntity(params); httpPost.setEntity(httpEntity); HttpClient httpClient = new DefaultHttpClient(); HttpResponse httpResponse = httpClient.execute(httpPost); if (httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) { response += EntityUtils.toString(httpResponse.getEntity()); } } catch (UnsupportedEncodingException e) { // TODO Auto-generated catch block Log.v("a2bgeek", "UnsupportedEncodingException--->" + e.getMessage()); } catch (ClientProtocolException e) { // TODO Auto-generated catch block Log.v("a2bgeek", "ClientProtocolException--->" + e.getMessage()); } catch (IOException e) { // TODO Auto-generated catch block Log.v("a2bgeek", "IOException--->" + e.getMessage()); } return response; }
服務器端是使用tornado框架編寫的,不了解的讀者請谷歌一下。
server.py
import tornado.ioloop import tornado.web from request import NormalRequestHandler application = tornado.web.Application([ (r"/normalrequest", NormalRequestHandler), ]) if __name__ == "__main__": application.listen(8888) tornado.ioloop.IOLoop.instance().start()request.py
import tornado.web class NormalRequestHandler(tornado.web.RequestHandler): def get(self): username = self.get_argument('username') password = self.get_argument('password') if username=='a2bgeek' and password=='123456': self.write('login success') else: self.write('login fail') def post(self): username = self.get_argument('username') password = self.get_argument('password') if username=='a2bgeek' and password=='123456': self.write('login success') else: self.write('login fail')在這裡有一點必須要提醒讀者,Android4.0以後涉及網絡的操作不能放在主線程裡面做了,所以需要開一個線程來做。
一般文件的上傳使用POST方式,因為GET對字節數有限制只能傳很少的數據,而POST理論上是沒有限制的。
public static String HttpURLConnectionFileUpload(File file) { String response = "HttpURLConnectionFileUpload "; String boundary = "a2bgeek"; try { String urlStr = "http://XXX.XXX.XXX.XXX:8888/fileupload"; URL url = new URL(urlStr); HttpURLConnection urlConnection = (HttpURLConnection) url .openConnection(); urlConnection.setDoInput(true); urlConnection.setDoOutput(true); urlConnection.setRequestMethod("POST"); urlConnection.setUseCaches(false); urlConnection.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary); urlConnection.connect(); DataOutputStream dos = new DataOutputStream( urlConnection.getOutputStream()); dos.writeBytes("--" + boundary); dos.writeBytes("\r\n"); dos.writeBytes("Content-Disposition: form-data; name=\"file\"; filename=\"" + file.getName() + "\"" + "\r\n"); dos.writeBytes("\r\n"); FileInputStream fis = new FileInputStream(file.getPath()); byte[] buffer = new byte[1024 * 1024]; int count = 0; while ((count = fis.read(buffer)) != -1) { dos.write(buffer, 0, count); } fis.close(); dos.writeBytes("\r\n"); dos.writeBytes("--" + boundary + "--"); dos.flush(); dos.close(); InputStream is = urlConnection.getInputStream(); BufferedReader br = new BufferedReader(new InputStreamReader(is)); String readLine = null; while ((readLine = br.readLine()) != null) { response += readLine; } is.close(); br.close(); urlConnection.disconnect(); } catch (MalformedURLException e) { // TODO Auto-generated catch block Log.v("a2bgeek", "MalformedURLException--->" + e.getMessage()); } catch (IOException e) { // TODO Auto-generated catch block Log.v("a2bgeek", "IOException--->" + e.getMessage()); } return response; }
public static String HttpClientFileUpload(File file) { String response = "HttpClientFileUpload "; try { String urlStr = "http://XXX.XXX.XXX.XXX:8888/fileupload"; HttpPost httpPost = new HttpPost(urlStr); MultipartEntity multipartEntity = new MultipartEntity(); multipartEntity.addPart("file", new FileBody(file)); httpPost.setEntity(multipartEntity); HttpClient httpClient = new DefaultHttpClient(); HttpResponse httpResponse = httpClient.execute(httpPost); if (httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) { response += EntityUtils.toString(httpResponse.getEntity()); } } catch (UnsupportedEncodingException e) { // TODO Auto-generated catch block Log.v("a2bgeek", "UnsupportedEncodingException--->" + e.getMessage()); } catch (ClientProtocolException e) { // TODO Auto-generated catch block Log.v("a2bgeek", "ClientProtocolException--->" + e.getMessage()); } catch (IOException e) { // TODO Auto-generated catch block Log.v("a2bgeek", "IOException--->" + e.getMessage()); } return response; }
import tornado.web import os class UploadFileHandler(tornado.web.RequestHandler): def get(self): self.write('''
一般文件的下載使用的是GET方式,其實也可以使用POST方式,這兩種是沒有本質區別的。只是GET比較方便,POST的話需要在服務器端編寫返回文件的代碼。
public static void HttpURLConnectionFileDownload() { try { int BUFFER_SIZE = 1024 * 1024; String urlStr = "http://XXX.XXX.XXX.XXX:8888/pic/one.png"; URL url = new URL(urlStr); HttpURLConnection urlConnection = (HttpURLConnection) url .openConnection(); InputStream is = urlConnection.getInputStream(); FileOutputStream fos = new FileOutputStream(new File(Environment .getExternalStorageDirectory().getPath() + "/NetConn/downone.png")); byte[] buffer = new byte[BUFFER_SIZE]; int count = 0; while ((count = is.read(buffer)) > 0) { fos.write(buffer, 0, count); } is.close(); fos.close(); Log.v("a2bgeek", "HttpURLConnectionFileDownload success"); } catch (MalformedURLException e) { // TODO Auto-generated catch block Log.v("a2bgeek", "MalformedURLException--->" + e.getMessage()); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } }
public static void HttpClientFileDownload() { try { int BUFFER_SIZE = 1024 * 1024; String urlStr = "http://XXX.XXX.XXX.XXX:8888/pic/two.png"; HttpGet httpGet = new HttpGet(urlStr); HttpClient httpClient = new DefaultHttpClient(); HttpResponse httpResponse = httpClient.execute(httpGet); HttpEntity httpEntity = httpResponse.getEntity(); InputStream is = httpEntity.getContent(); FileOutputStream fos = new FileOutputStream(new File(Environment .getExternalStorageDirectory().getPath() + "/NetConn/downtwo.png")); byte[] buffer = new byte[BUFFER_SIZE]; int count = 0; while ((count = is.read(buffer)) > 0) { fos.write(buffer, 0, count); } is.close(); fos.close(); Log.v("a2bgeek", "HttpClientFileDownload success"); } catch (ClientProtocolException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } }
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shape_rectangle.xml shape_oval.xml shape_line.xml
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