//使用HttpURLConnection get 实现网络数据请求 

public class HttpUtils {
    private static final String TAG = "HttpUtils----";
    //单利模式
    private static HttpUtils httpUtils = new HttpUtils();
    private final static int SUCCESS = 0;
    private final static int ERROR = 1;
    private MyHandler myHandler = new MyHandler();
    private HttpUtilsListener httpUtilsListener;

    public static HttpUtils getInstance() {
        if (httpUtils == null) {
            httpUtils = new HttpUtils();
        }
        return httpUtils;
    }

    //封装get
    public void get(final String url) {
        new Thread() {
            @Override
            public void run() {
                //进行网络请求
                try {
                    URL url1 = new URL(url);
                    HttpURLConnection connection = (HttpURLConnection) url1.openConnection();
                    connection.setConnectTimeout(3000);
                    if (connection.getResponseCode() == 200) {
                        InputStream inputStream = connection.getInputStream();
                        //inputstream--string
                        String json = inputStreamToString(inputStream);
                        //发送
                        Message message = myHandler.obtainMessage();
                        message.what = SUCCESS;
                        message.obj = json;
                        myHandler.sendMessage(message);

                    } else {
                        Message message = myHandler.obtainMessage();
                        message.what = ERROR;
                        message.obj = "失败";
                        myHandler.sendMessage(message);
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                    Message message = myHandler.obtainMessage();
                    message.what = ERROR;
                    message.obj = e.getMessage();
                    myHandler.sendMessage(message);
                }
            }
        }.start();
    }

    //使用Handler 处理线程问题
    class MyHandler extends Handler {
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
                case SUCCESS:
                    //成功
                    String json = (String) msg.obj;
                    Log.d(TAG, "handleMessage: " + json);
                    //使用回调
                    httpUtilsListener.getDataSuccess(json);
                    break;
                case ERROR:
                    //成功
                    String error = (String) msg.obj;
                    Log.d(TAG, "handleMessage: " + error);
                    //使用回调
                    httpUtilsListener.getDataError(error);
                    break;
            }
        }
    }

    public String inputStreamToString(InputStream inputStream) throws IOException {
        int len = 0;
        byte[] butter = new byte[1024];
        StringBuffer stringBuffer = new StringBuffer();
        while ((len = inputStream.read(butter)) != -1) {
            String s = new String(butter, 0, len);
            stringBuffer.append(s);

        }
        return stringBuffer.toString();
    }

    //接口回调
    public interface HttpUtilsListener {
        void getDataSuccess(String json);

        void getDataError(String error);
    }

    //外部访问的方法
    public void setHttpUtilsListener(HttpUtilsListener httpUtilsListener) {
        this.httpUtilsListener = httpUtilsListener;
    }
}