Android 怎么用HttpURLConnection访问网络？

HttpURLConnection connection = null;
try {
 URL url = new URL("https://www.xxx.com/");
 connection = (HttpURLConnection) url.openConnection();
 connection.setRequestMethod("GET");//设置访问方式为“GET”
 connection.setConnectTimeout(8000);//设置连接服务器超时时间为8秒
 connection.setReadTimeout(8000);//设置读取服务器数据超时时间为8秒

 if (HttpURLConnection.HTTP_OK == connection.getResponseCode()) {
  //从服务器获取响应并把响应数据转为字符串打印
  InputStream in = connection.getInputStream();
  BufferedReader reader = new BufferedReader(new InputStreamReader(in));

  StringBuilder response = new StringBuilder();
  String line;
  while (null != (line = reader.readLine())) {
    response.append(line);
  }
  Log.d(TAG, response.toString());
 }
} catch (Exception e) {
 e.printStackTrace();
} finally {
 if (null!= connection) {
   connection.disconnect();
 }
}

HttpURLConnection connection = null;
  try{
   URL url = new URL("https://www.xxx.com/");
   connection = (HttpURLConnection) url.openConnection();

   connection.setRequestMethod("POST");
   connection.setConnectTimeout(8000);
   connection.setReadTimeout(8000);
   connection.setDoOutput(true);// 使用 URL 连接进行输出
   connection.setDoInput(true);// 使用 URL 连接进行输入
   connection.setUseCaches(false);// 忽略缓存

   // 建立输出流，并写入数据
   OutputStream outputStream = connection.getOutputStream();
   DataOutputStream dataOutputStream = new DataOutputStream(outputStream);
   dataOutputStream.writeBytes("username=admin&password=888888");
   dataOutputStream.close();

   if (HttpURLConnection.HTTP_OK == connection.getResponseCode()) {
    // 当正确响应时处理数据
    StringBuffer response = new StringBuffer();
    String line;
    BufferedReader responseReader = 
      new BufferedReader(new InputStreamReader(connection.getInputStream(), "utf-8"));
    // 处理响应流，必须与服务器响应流输出的编码一致
    while (null != (line = responseReader.readLine())) {
     response.append(line);
    }
    responseReader.close();
    Log.d(TAG, response.toString());
   }

  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   if (null!= connection) {
    connection.disconnect();
   }
  }