1   public void urlConnection() 2    { 3        String urltext = ""; 4        try { 5 //          方法一： 6           URL url = new URL(urltext); 7           URLConnection conn = url.openConnection();//取得一个新的链接对指定的URL 8           conn.connect();//本方法不会自动重连 9           InputStream is = conn.getInputStream();10           is.close();//关闭InputStream11 //          方法二：12           URL url2 = new URL(urltext);13           InputStream is2 = url2.openStream();14           is2.close();//关闭InputStream15           //URL对象也提供取得InputStream的方法。URL.openStream()会打开自动链接，所以不需要运行openConnection16 17           //方法三：本方法同一，但是openConnection返回值直接转为HttpsURLConnection，18           //这样可以使用一些Http连接特有的方法,如setRequestMethod19           URL url3 = new URL(urltext);20           HttpsURLConnection conn3 =(HttpsURLConnection)url.openConnection();21           conn3.setRequestMethod("POST");22           //允许Input、Output,不使用Cache23           conn3.setDoInput(true);24           conn3.setDoOutput(true);25           conn3.setUseCaches(false);26           /*27            * setRequestProperty28            */29           conn3.setRequestProperty("Connection", "Keep-Alive");30           conn3.setRequestProperty("Charset", "UTF-8");31           conn3.setRequestProperty("Content-type", "multipart/form-data;boundary=*****");32           //在与服务器连接之前，设置一些网络参数33           conn3.setConnectTimeout(10000);34           35           conn3.connect();36         // 与服务器交互:向服务器端写数据，这里可以上传文件等多个操作37           OutputStream outStream = conn3.getOutputStream();38           ObjectOutputStream objOutput = new ObjectOutputStream(outStream);39           objOutput.writeObject(new String("this is a string…"));40           objOutput.flush();41     42           // 处理数据, 取得响应内容43           InputStream is3 = conn.getInputStream();44           is3.close();//关闭InputStream45        } catch (IOException e) {46             // TODO Auto-generated catch block47             e.printStackTrace();48         }49    }