Android 加载图片显示加载进度

我使用该功能显示图片：

Bitmap imageBitmap = loadBitmap(URL);

加载位图，如下所示：

private Bitmap loadBitmap(String url) {
try {
Bitmap bm = BitmapFactory.decodeStream((InputStream)this.fetch(url));
return bm;
}
catch(Exception e) {
e.printStackTrace();
return null;
}
} 

并获取以下信息：

public Object fetch(String address) {
try {
URL url = new URL(address);
Object content = url.getContent();
return content;
}
catch(Exception e) {
e.printStackTrace();
}
return this;
}

我想在加载时显示加载进度或load.png。 并以图片加载结束并显示它。 我该怎么办？ 我试着做一些类似的对话。 但是我不知道怎么用？

你可以用a来做这个。 查看以下链接：

你可以用a来做这个。 查看以下链接：

---

你不能直接这么做，因为Android不支持GIF文件。因此，为了消除这种情况，您必须创建单独的图像，将图像加载到分割图像中并制作动画。加载时，运行动画，一旦位图可用，停止动画并在ImageView上设置位图，您不能直接这样做，因为Android不支持GIF文件。因此，为了消除这种情况，您必须创建单独的图像，将图像加载到分割图像中并制作动画。加载时，运行动画，一旦位图可用，停止动画并在ImageView上设置位图

此示例在下载图像时显示progressbar，稍后它将不可见

public class ImageDownload extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main1);

        ImageView mainImageView = (ImageView) findViewById(R.id.imageView);
        ProgressBar progressBar = (ProgressBar) findViewById(R.id.progressBar);
        String imageurl = "http://ipadwallpaperportal.com/wp-content/main/2011_09/purple-flower-close-up-1024x1024-wallpaper.jpg";
        ImageDownloadMessageHandler imageDownloadMessageHandler1 = new ImageDownloadMessageHandler(
                progressBar, mainImageView);
        ImageDownlaodThread imageDownlaodThread = new ImageDownlaodThread(
                imageDownloadMessageHandler1, imageurl);
        imageDownlaodThread.start();

    }

    class ImageDownlaodThread extends Thread {
        ImageDownloadMessageHandler imageDownloadMessageHandler;
        String imageUrl;

        public ImageDownlaodThread(
                ImageDownloadMessageHandler imageDownloadMessageHandler,
                String imageUrl) {
            this.imageDownloadMessageHandler = imageDownloadMessageHandler;
            this.imageUrl = imageUrl;
        }

        @Override
        public void run() {
            Drawable drawable = LoadImageFromWebOperations(imageUrl);
            Message message = imageDownloadMessageHandler.obtainMessage(1,
                    drawable);
            imageDownloadMessageHandler.sendMessage(message);
            System.out.println("Message sent");
        }

    }

    class ImageDownloadMessageHandler extends Handler {
        ProgressBar progressBar;
        View imageTextView;

        public ImageDownloadMessageHandler(ProgressBar progressBar,
                View imageTextView) {
            this.progressBar = progressBar;
            this.imageTextView = imageTextView;
        }

        @Override
        public void handleMessage(Message message) {
            progressBar.setVisibility(View.GONE);
            imageTextView.setBackgroundDrawable(((Drawable) message.obj));
            imageTextView.setVisibility(View.VISIBLE);
        }

    }

    Drawable LoadImageFromWebOperations(String strUrl) {
        /**
         * This is one method
         */
        long x1 = System.currentTimeMillis();

        Drawable d = null;
        InputStream is = null;
        try {
            is = (InputStream) new URL(strUrl).getContent();
            d = Drawable.createFromStream(is, "src name");
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        long x2 = System.currentTimeMillis();
        long res = x2 - x1;
        Log.v("Image Downloading Time", "" + res);
}

---

此示例在下载图像时显示progressbar，稍后它将不可见

public class ImageDownload extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main1);

        ImageView mainImageView = (ImageView) findViewById(R.id.imageView);
        ProgressBar progressBar = (ProgressBar) findViewById(R.id.progressBar);
        String imageurl = "http://ipadwallpaperportal.com/wp-content/main/2011_09/purple-flower-close-up-1024x1024-wallpaper.jpg";
        ImageDownloadMessageHandler imageDownloadMessageHandler1 = new ImageDownloadMessageHandler(
                progressBar, mainImageView);
        ImageDownlaodThread imageDownlaodThread = new ImageDownlaodThread(
                imageDownloadMessageHandler1, imageurl);
        imageDownlaodThread.start();

    }

    class ImageDownlaodThread extends Thread {
        ImageDownloadMessageHandler imageDownloadMessageHandler;
        String imageUrl;

        public ImageDownlaodThread(
                ImageDownloadMessageHandler imageDownloadMessageHandler,
                String imageUrl) {
            this.imageDownloadMessageHandler = imageDownloadMessageHandler;
            this.imageUrl = imageUrl;
        }

        @Override
        public void run() {
            Drawable drawable = LoadImageFromWebOperations(imageUrl);
            Message message = imageDownloadMessageHandler.obtainMessage(1,
                    drawable);
            imageDownloadMessageHandler.sendMessage(message);
            System.out.println("Message sent");
        }

    }

    class ImageDownloadMessageHandler extends Handler {
        ProgressBar progressBar;
        View imageTextView;

        public ImageDownloadMessageHandler(ProgressBar progressBar,
                View imageTextView) {
            this.progressBar = progressBar;
            this.imageTextView = imageTextView;
        }

        @Override
        public void handleMessage(Message message) {
            progressBar.setVisibility(View.GONE);
            imageTextView.setBackgroundDrawable(((Drawable) message.obj));
            imageTextView.setVisibility(View.VISIBLE);
        }

    }

    Drawable LoadImageFromWebOperations(String strUrl) {
        /**
         * This is one method
         */
        long x1 = System.currentTimeMillis();

        Drawable d = null;
        InputStream is = null;
        try {
            is = (InputStream) new URL(strUrl).getContent();
            d = Drawable.createFromStream(is, "src name");
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        long x2 = System.currentTimeMillis();
        long res = x2 - x1;
        Log.v("Image Downloading Time", "" + res);
}

您可以使用AsyncTask在PreExecute方法上显示进度对话框，并在PostExecute方法中隐藏/取消它

您可以使用AsyncTask在PreExecute方法上显示进度对话框，并在PostExecute方法中隐藏/取消它

DownloadBitmap dd = new DownloadBitmap();
dd.execute();