【Android每周专题】网络编程
本系列文章均为A2BGeek原创,转载务必在明显处注明:
转载自A2BGeek的【Android每周专题】系列,原文链接:http://blog.csdn.net/a2bgeek/article/details/11580395
本期专题将讲解网络编程。
很多APP或多或少会有一些访问网络的功能,比如用户的登录,文件的上传和下载,更新等功能,本期专题将注重实践,会有大量的代码,读者可以直接拷贝使用。
概述
HTTP 协议可能是现在 Internet 上使用得最多、最重要的协议了,在 JDK 的 java.net 包中已经提供了访问 HTTP 协议的基本功能:HttpURLConnection。HttpURLConnection是java的标准类,HttpURLConnection继承自URLConnection,可用于向指定网站发送GET请求、POST请求。
在一般情况下,如果只是需要Web站点的某个简单页面提交请求并获取服务器响应,HttpURLConnection完全可以胜任。但在绝大部分情况下,Web站点的网页可能没这么简单,这些页面并不是通过一个简单的URL就可访问的,可能需要用户登录而且具有相应的权限才可访问该页面。在这种情况下,就需要涉及Session、Cookie的处理了,如果打算使用HttpURLConnection来处理这些细节,当然也是可能实现的,只是处理起来难度就大了。
为了更好地处理向Web站点请求,包括处理Session、Cookie等细节问题,Apache开源组织提供了一个HttpClient项目,看它的名称就知道,它是一个简单的HTTP客户端(并不是浏览器),可以用于发送HTTP请求,接收HTTP响应。但不会缓存服务器的响应,不能执行HTML页面中嵌入的Javascript代码,也不会对页面内容进行任何解析、处理。
简单来说,HttpClient就是一个增强版的HttpURLConnection,HttpURLConnection可以做的事情HttpClient全部可以做;HttpURLConnection没有提供的有些功能,HttpClient也提供了,但它只是关注于如何发送请求、接收响应,以及管理HTTP连接。简单登录功能
这里说的用户登录仅仅是向服务器发送用户名和密码,服务器验证一下,返回一个标志(比如1代表用户名和密码正确登录成功),真正的登录功能是没有这么简单的,还需要维护Session。在本小节我将通过四种方式编写登录代码,分别是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的网络编程。服务器端我选用了Facebook的开源框架Tornado,服务器端大家可以根据自己的喜好选择,比如LAMP的经典组合。接下来就直接上代码了。
HttpURLConnection GET
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 blockLog.v("a2bgeek", "MalformedURLException--->" + e.getMessage());} catch (IOException e) {// TODO Auto-generated catch blockLog.v("a2bgeek", "IOException--->" + e.getMessage());}return response;}我电脑的IP地址就不写啦,用XXX代替了。
HttpURLConnection POST
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 blockLog.v("a2bgeek", "MalformedURLException--->" + e.getMessage());} catch (IOException e) {// TODO Auto-generated catch blockLog.v("a2bgeek", "IOException--->" + e.getMessage());}return response;}
HttpGet
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 blockLog.v("a2bgeek", "ClientProtocolException--->" + e.getMessage());} catch (IOException e) {// TODO Auto-generated catch blockLog.v("a2bgeek", "IOException--->" + e.getMessage());}return response;}
HttpPost
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);List<NameValuePair> params = new ArrayList<NameValuePair>();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 blockLog.v("a2bgeek","UnsupportedEncodingException--->" + e.getMessage());} catch (ClientProtocolException e) {// TODO Auto-generated catch blockLog.v("a2bgeek", "ClientProtocolException--->" + e.getMessage());} catch (IOException e) {// TODO Auto-generated catch blockLog.v("a2bgeek", "IOException--->" + e.getMessage());}return response;}
服务器端代码
服务器端是使用tornado框架编写的,不了解的读者请谷歌一下。
server.py
import tornado.ioloopimport tornado.webfrom request import NormalRequestHandlerapplication = tornado.web.Application([ (r"/normalrequest", NormalRequestHandler),])if __name__ == "__main__": application.listen(8888) tornado.ioloop.IOLoop.instance().start()request.py
import tornado.webclass 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')在这里有一点必须要提醒读者,Android4.0以后涉及网络的操作不能放在主线程里面做了,所以需要开一个线程来做。
文件的上传
一般文件的上传使用POST方式,因为GET对字节数有限制只能传很少的数据,而POST理论上是没有限制的。
HttpURLConnection POST
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 blockLog.v("a2bgeek", "MalformedURLException--->" + e.getMessage());} catch (IOException e) {// TODO Auto-generated catch blockLog.v("a2bgeek", "IOException--->" + e.getMessage());}return response;}
HttpPost
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 blockLog.v("a2bgeek","UnsupportedEncodingException--->" + e.getMessage());} catch (ClientProtocolException e) {// TODO Auto-generated catch blockLog.v("a2bgeek", "ClientProtocolException--->" + e.getMessage());} catch (IOException e) {// TODO Auto-generated catch blockLog.v("a2bgeek", "IOException--->" + e.getMessage());}return response;}
服务器端代码
import tornado.webimport osclass UploadFileHandler(tornado.web.RequestHandler): def get(self): self.write('''<html> <head><title>Upload File</title></head> <body> <form action='fileupload' enctype="multipart/form-data" method='post'> <input type='file' name='file'/><br/> <input type='submit' value='submit'/> </form> </body></html>''') def post(self): upload_path=os.path.join(os.path.dirname(__file__),'files') if not os.path.exists(upload_path): os.makedirs(upload_path) file_metas=self.request.files['file'] for meta in file_metas: filename=meta['filename'] filepath=os.path.join(upload_path,filename) with open(filepath,'w') as up: up.write(meta['body']) self.write('upload success')
文件的下载
一般文件的下载使用的是GET方式,其实也可以使用POST方式,这两种是没有本质区别的。只是GET比较方便,POST的话需要在服务器端编写返回文件的代码。
HttpURLConnection GET
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 blockLog.v("a2bgeek", "MalformedURLException--->" + e.getMessage());} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}
HttpGet
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 blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}
好了今天就到这里了,代码的大部分已经放在博客里面了,由于个人时间紧张,上传代码又要等很长时间,代码就不贴了,需要的同学可以留言。
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