public class HttpUtils {
 public static byte[] get(String urlString) {
  HttpURLConnection urlConnection = null;
  try {
   URL url = new URL(urlString);
   urlConnection = (HttpURLConnection) url.openConnection();
   //设置请求方法
   urlConnection.setRequestMethod("GET");
   //设置超时时间
   urlConnection.setConnectTimeout(5000);
   urlConnection.setReadTimeout(3000);

   //获取响应的状态码
   int responseCode = urlConnection.getResponseCode();
   if (responseCode == 200) {
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    InputStream in = urlConnection.getInputStream();
    byte[] buffer = new byte[4 * 1024];
    int len = -1;
    while((len = in.read(buffer)) != -1) {
     bos.write(buffer, 0, len);
    }
    close(in);
    byte[] result = bos.toByteArray();
    close(bos);
    return result;
   } else {
    return null;
   }
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   if (urlConnection != null) {
    urlConnection.disconnect();
   }
  }

  return null;
 }

 private static void close(Closeable stream) {
  if (stream != null) {
   try {
    stream.close();
   } catch (IOException e) {
    e.printStackTrace();
   }
  }
 }

} 

public class AsyncHttpUtils {public static byte[] get(String url, ResponseHandler handler) {
  final Handler mHandler = new Handler();
  new Thread(new Runnable() {
   @Override
   public void run() {
    final byte[] result = HttpUtils.get(url);
    handler.post(new Runnable() {
     @Override
     public void run() {
      responseHandler.onSuccess(result);
     }
    });
   }
  });
 }
} 

public interface ResponseHandler {
 void onSucess(bytep[] result);
}
 

public class AsyncHttpUtils {
 //获取当前设备的CPU数
 public static final int CPU_COUNT = Runtime.getRuntime().availableProcessors();
 //核心池大小设为CPU数加1
 private static final int CORE_POOL_SIZE = CPU_COUNT + 1;
 //设置线程池的最大大小
 private static final int MAX_POOL_SIZE = 2 * CPU_COUNT + 1;
 //存活时间
 private static final long KEEP_ALIVE = 5L;
 
 //创建线程池对象
 public static final Executor threadPoolExecutor = new ThreadPoolExecutor(CORE_POOL_SIZE,
   MAX_POOL_SIZE, KEEP_ALIVE, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>());

 public static void get(final String url, final ResponseHandler responseHandler) {
  final Handler mHandler = new Handler(Looper.getMainLooper());
  
  //创建一个新的请求任务
  Runnable requestRunnable = new Runnable() {
   @Override
   public void run() {
    final byte[] result = HttpUtils.get(url);
    if (result != null) {
     mHandler.post(new Runnable() {
      @Override
      public void run() {
       //result不为空表明请求成功，回调onSuccess方法
       responseHandler.onSuccess(result);
      }
     });
    }
   }
  };
  threadPoolExecutor.execute(requestRunnable);
 }
}