Android如何给asp网页传递参数?

我想做一个学校图书馆的手机客户端,图书馆网页http://222.24.94.225/gdlisnet/ReaderLogin.aspx登陆时需选择登录方式,学号和密码.然后登陆成功跳转到http://222.24.94.225/gdlisnet/ReaderTable.aspx.我使用一下传递参数,

String url = "http://222.24.94.225/gdlisnet/ReaderLogin.aspx?";
            HttpPost httpre = new HttpPost(url);
            List<NameValuePair> params = new ArrayList<NameValuePair>();
            BasicNameValuePair pair1 = new BasicNameValuePair("DropDownList1", "借书证号");
            BasicNameValuePair pair2 = new BasicNameValuePair("TextBox1", "我的学号");
            BasicNameValuePair pair3 = new BasicNameValuePair("TextBox2", "我的密码");
            params.add(pair1);
            params.add(pair2);
            params.add(pair3);
            try {
                HttpEntity entity = new UrlEncodedFormEntity(params,"utf-8");
                httpre.setEntity(entity);
                HttpClient httpClient = new DefaultHttpClient();
                HttpResponse response = httpClient.execute(httpre);
                if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                    String result = EntityUtils.toString(response.getEntity());
                    //Looper.prepare();
                    tv.setText(result);
                    //Looper.loop();
                } else {
                    tv.setText("应答错误");
                }
            } catch (UnsupportedEncodingException e) {
                // TODO: handle exception
                e.printStackTrace();
            }catch(ClientProtocolException e){
                e.printStackTrace();
            }catch (IOException e){
                e.printStackTrace();
            }

但是得不到登陆后的页面源代码,为何?

可能是因为图书馆网站使用了防抓取技术。您可以尝试添加请求头信息，模拟浏览器请求，试图绕过防抓取措施。添加请求头信息的代码如下：

httpre.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/89.0.4389.82 Safari/537.36");
httpre.setHeader("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9");