本文使用okHttp+Jsoup,所需要的JAR请自行在网上下载,添加JAR的方式,参见http://blog.csdn.net/ervincm/article/details/67821256

import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;

import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
public class LoginActivity extends Activity {

    private ImageView checkCodePicture;
     private OkHttpClient client;
      public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);
        setContentView(R.layout.login_main);  
            initView();  
            loadingCaptchaPic();
            }
   public void initView() {  
        Log.i(TAG, "初始化视图控件");  

    ;
        checkCodePicture=(ImageView) findViewById(R.id.checkCode_picture);

    }  
      public void loadingCaptchaPic() {

          client=new OkHttpClient();

        //加载验证码图片代码
        new Thread(new Runnable() {
            String src;
            Bitmap captchaPic;

            @Override
            public void run() {
                try{

                    //http使用get方式获得返回的html代码
                    Request request = new Request.Builder()
                            .url("http://hdhome.org/login.php")
                            .build();
                    Response response = client.newCall(request).execute();
                    String responseData = response.body().string();//返回的内容

                    //jsoup解析,从而得到动态验证码的url地址
                    Document parse = Jsoup.parse(responseData);
                    Elements select = parse.select("img[alt=CAPTCHA]");
                    Element element = select.get(0);
                    src = element.attr("src");
                     String imagehash = src.substring(36);
                     System.out.println("imagehash"+src);

                   //get方式请求验证码url地址,得到返回验证码图片文件
                    request = new Request.Builder()
                            .url("http://hdhome.org/"+src)
                            .build();
                    response = client.newCall(request).execute();
                    InputStream is = response.body().byteStream();

                   captchaPic = BitmapFactory.decodeStream(is);


                    checkCodePicture.post(new Runnable() {
                        @Override
                        public void run() {
                            checkCodePicture.setImageBitmap(captchaPic);
                        }
                    });
                }catch(Exception e){
                    e.printStackTrace();
                }
            }
        }).start();
    }


    }