网络模块
1、URL
--------openStream()
return InputStream
--------openConnection()
return URLConnection
2、URLConnection
--------getInputStream()用于获取URLConnection响应的内容
--------getOutputStream()用户向URLConnection发送请求参数
2、HttpURLConnection
--------getResponseCode()
--------getResponseMessage()
--------getRequestMethod()
--------setRequestMethod()
3、HttpClient
--------execute()
--------setParams()
--------setEntity()
--------getHeaders()
--------getAllHeaders()
4、Webservice