在Android应用中加载和显示位图需要很长时间

时间:2014-05-30 15:18:15

标签: java android listview bitmap

现在我有一个LocationAdapter类,它接收我的"Location"对象,并将每个Location显示为ListView。我试图在Bitmap图像中传递它并让它在ListView行中显示该图像。它工作正常,但即使加载了行中的文本,图像也需要一段时间才能加载。我正在测试一个实际的设备。这是我的活动代码:

public class MainActivity extends ActionBarActivity {

ArrayList<Location> arrayOfLocations;
LocationAdapter adapter;
private static Bitmap bitmap;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
            WindowManager.LayoutParams.FLAG_FULLSCREEN);
    setContentView(R.layout.activity_main);

    // Construct the data source
    arrayOfLocations = new ArrayList<Location>();

    // Create the adapter to convert the array to views
    adapter = new LocationAdapter(this, arrayOfLocations);

    Bitmap image = getBitmapFromID(1);

    adapter.add(new Location(image, "Place 1",
            "We have the freshest fruit in the whole world!", "2 miles",
            "8-5 mon-sat\nclosed sun"));
    adapter.add(new Location(image, "Place 2",
            "We have the freshest fruit in the whole world!", "2 miles",
            "8-5 mon-sat"));
    adapter.add(new Location(image, "Place 3",
            "We have the best cakes in the whole world!", "2 miles",
            "8-5 mon-fri\n10-1 sat\nclosed sun\nclosed Memorial Day"));
    adapter.add(new Location(image, "Fruit Stand",
            "Best place!", "2 miles",
            "8-5 mon-sat"));
    adapter.add(new Location(image, "Place 4",
            "Food!", "2 miles",
            "8-5 mon-sat"));
    adapter.add(new Location(image, "Place 5",
            "Toys!", "2 miles",
            "8-5 mon-sat"));

    // Attach the adapter to a ListView
    ListView listView = (ListView) findViewById(R.id.listView1);

    View header = (View) getLayoutInflater().inflate(
            R.layout.listview_header, null);
    listView.addHeaderView(header);

    listView.setAdapter(adapter);

}

public static Bitmap getBitmapFromID(int id) {

    //final Bitmap bitmap;

    Thread thread = new Thread(new Runnable() {
        @Override
        public void run() {

            try {
                bitmap = BitmapFactory
                        .decodeStream((InputStream) new URL(
                                "http://icons.iconarchive.com/icons/yellowicon/game-stars/256/Mario-icon.png")
                                .getContent());

            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
    });

    thread.start();
    return bitmap;
}

}

我做错了什么吗?这需要一段时间加载是正常的吗?谢谢!

3 个答案:

答案 0 :(得分:1)

你需要在后台线程中AsyncTask你的工作。然而,为了更好的方法,请看一下:

https://stackoverflow.com/a/23941258/276949

Android Volley是Google推出的一款非常新的非详细资料库,可以很好地加载图像,并且可以自动处理单独线程上的所有下载。

答案 1 :(得分:0)

加载位图可能需要一段时间,您可以在此处阅读:Android doc。但是,您需要同步您的线程,因为在调用start()之后,该方法立即返回。你需要收到一个&#34;嘿,我已经完成了#34;从你的线程,然后加载位图。

答案 2 :(得分:0)

您是否可以将Mario_icon.png放置在应用内部,而不是通过网址进行访问?这样,应用程序将花费更少的时间来检索图像,并且它将允许应用程序需要更少的权限

当您需要连接到网址时,加载图片需要更长的时间。