android发送数据到服务器的问题

Question

我用java单独测试能行，放到android里面就不行了，怎么回事，我是访问servelet的
public class HTTPDemoActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button btn = (Button) findViewById(R.id.send);
btn.setOnClickListener(new OnClickListener() { @Override
public void onClick(View v) {
URL url = null;
HttpURLConnection httpurlconnection = null;
try {
url = new URL("http://192.168.21.1:8080/GETDemo/MyServlet");
httpurlconnection = (HttpURLConnection) url.openConnection();
httpurlconnection.setDoOutput(true);
httpurlconnection.setRequestMethod("POST");
OutputStream out = httpurlconnection.getOutputStream();
out.write("daishunchao".getBytes());
out.write("&".getBytes());
out.write("wangling".getBytes());
out.flush();
out.close();
/* int code = httpurlconnection.getResponseCode();
// System.out.println("code" + code);
if (200 == code) {
InputStream is = httpurlconnection.getInputStream();
int a;
while ((a = is.read()) != -1) {
System.out.print("" + (char) a);
}
is.close();
} else {
System.out.println("an error occur!");
}*/ } catch (Exception e) {
e.printStackTrace();
System.out.println("失败了");
} finally {
if (httpurlconnection != null)
httpurlconnection.disconnect();
}
}
});
}
}