安卓：活动时间太长，因为Web服务的HTTP请求来显示 [英] Android: Activity taking too long to display because of web service Http Request

问题描述

我的一个活动，做一个HTTP请求到web服务得到一些气象数据，当我启动应用程序。

该活动将采取3-4秒因为Web服务请求中显示的问题。 （测试实际设备）

我知道我米不这样做的正确的方式。所有我米做的是对的onCreate方法，我为发出请求，得到了XML回来，解析和显示数据。

什么是处理在Android的Web服务请求，这样应用程序将不会显示一个白色的屏幕发出请求，而最好的方法是什么？也许有些线程.......

我知道这是不会发生在其他的应用程序，我有我的设备，使请求来获取实时数据。

注：

1）我取回XML是没有那么大（5种元素与每一个5嵌套元素）。

2）我试图与3G网络和Wifi但响应时间仍然是相同的。

样品code：

  @覆盖
    公共无效的onCreate（包冰柱）{
    super.onCreate（冰柱）;
    的setContentView（R.layout.clock_weather）;

   //这是它提出请求并解析XML。
    WeatherSet设定= getWeatherCondition（纽约）;

    TextView的currentWeather =（TextView中）findViewById（R.id.current_weather）;
    currentWeather.setText（+ set.getWeatherCurrentCondition（）getTempFahrenheit（））;

    TextView的currentWeatherH =（TextView中）findViewById（R.id.current_weatherH）;
    currentWeatherH.setText（H：+ set.getWeatherForecastConditions（）得到（0）.getTempMaxFahrenheit（））;

    TextView的currentWeatherL =（TextView中）findViewById（R.id.current_weatherL）;
    currentWeatherL.setText（L：+ set.getWeatherForecastConditions（）得到（0）.getTempMinFahrenheit（））;

    ImageView的currentWeatherIcon =（ImageView的）findViewById（R.id.current_weather_icon）;
    字符串IMAGEURL = set.getWeatherCurrentCondition（）getIconURL（）。
    可绘制bitmapDrawable = getImageBitmap（IMAGEURL）;
    currentWeatherIcon.setImageDrawable（bitmapDrawable）;

    setForecastInfo（套，R.id.day1，R.id.day1_icon，R.id.day1_temp，1）;
    setForecastInfo（套，R.id.day2，R.id.day2_icon，R.id.day2_temp，2）;
    setForecastInfo（套，R.id.day3，R.id.day3_icon，R.id.day3_temp，3）;
    setForecastInfo（集，R.id.day4，R.id.day4_icon，R.id.day4_temp，4）;
}
 

解决方案

的时间为你的反应是联合国predictable - 您的网络连接可以是非常差的，并采取秒传输几个字节。所以正确的方式做到这一点（如你建议）是使用线程。在我们的例子Android提供了非常有用的类来处理这样的情况 - AsynTask 。在阅读的文档，你会发现，它有3个非常强大的方法，可以帮助你

1. 在preExecute 运行在UI线程 - 非常有帮助显示一些微调或者一些进度指示器，说明你正在做一些背景工作的用户
2. <一个href="http://developer.android.com/reference/android/os/AsyncTask.html#doInBackground%28Params...%29"相对=nofollow> doInBackground 在后台运行 - 在这里做你的工作背景
3. onPostExecute 运行在在UI线程 - 当你完成你的工作背景隐藏进度，并与新接收的数据更新GUI
。

One of my activities make a http request to a webservice to get some weather data when I start the application.

The issue that the activity will take 3-4 seconds to display because of the webservice request. ( Tested on actual device )

I know I m not doing this the right way. All I m doing is on the onCreate method, I m making the request , getting the xml back, parsing and displaying the data.

What is the best way to deal with webservice requests in Android so the application won't display a white screen while the request is being made? Maybe some threads.......

I know this is not happening on other application I have in my device that make request to get live data.

Notes:

1) The xml I getting back is not that big ( 5 elements with 5 nested elements on each one).

2) I tried with the 3G network and Wifi but the response time is still the same.

sample code:

   @Override
    public void onCreate(Bundle icicle) {
    super.onCreate(icicle);
    setContentView(R.layout.clock_weather);

   // this is where it is making the request and parsing the xml.
    WeatherSet set = getWeatherCondition("New York, NY");

    TextView currentWeather  = (TextView) findViewById(R.id.current_weather);
    currentWeather.setText("" + set.getWeatherCurrentCondition().getTempFahrenheit());

    TextView currentWeatherH  = (TextView) findViewById(R.id.current_weatherH);
    currentWeatherH.setText("H: " + set.getWeatherForecastConditions().get(0).getTempMaxFahrenheit());

    TextView currentWeatherL  = (TextView) findViewById(R.id.current_weatherL);
    currentWeatherL.setText("L: " + set.getWeatherForecastConditions().get(0).getTempMinFahrenheit());

    ImageView currentWeatherIcon  = (ImageView) findViewById(R.id.current_weather_icon);
    String imageUrl = set.getWeatherCurrentCondition().getIconURL();
    Drawable bitmapDrawable = getImageBitmap(imageUrl);
    currentWeatherIcon.setImageDrawable(bitmapDrawable); 

    setForecastInfo(set, R.id.day1, R.id.day1_icon, R.id.day1_temp, 1  );   
    setForecastInfo(set, R.id.day2, R.id.day2_icon, R.id.day2_temp, 2  );   
    setForecastInfo(set, R.id.day3, R.id.day3_icon, R.id.day3_temp, 3 );    
    setForecastInfo(set, R.id.day4, R.id.day4_icon, R.id.day4_temp, 4  );
}

解决方案

The time for your response is unpredictable - your network connection can be very poor and take seconds to transfer a few bytes. So the correct way to do this ( as you propose ) is to use thread. In our case android provides very useful class to handle this situations - AsynTask. After you read the docs you will notice that it has 3 very powerful methods that can help you

1. onPreExecute runs in the ui thread - very helpful to show some spinner or some progress indicator to show the user that you are doing some work in background
2. doInBackground runs in background - do your background work here
3. onPostExecute runs in the ui thread- when your are done with your background work hide the progress and update the gui with the newly received data.

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