Android编程学习之异步加载图片的方法

return null; }

} // 解码图像和缩放以减少内存的消耗

private Bitmap decodeFile(File f) { try {

// 解码图像尺寸 BitmapFactory.Options o = new BitmapFactory.Options();

o.inJustDecodeBounds = true; BitmapFactory.decodeStream(new FileInputStream(f), null, o);

// 找到正确的缩放值。这应该是2的幂。 final int REQUIRED_SIZE = 70;

int width_tmp = o.outWidth, height_tmp = o.outHeight; int scale = 1;

while (true) { if (width_tmp / 2 < REQUIRED_SIZE

|| height_tmp / 2 < REQUIRED_SIZE) break;

width_tmp /= 2; height_tmp /= 2;

scale *= 2; }

// 设置恰当的inSampleSize可以使BitmapFactory分配更少的空间 // 用正确恰当的inSampleSize进行decode

BitmapFactory.Options o2 = new BitmapFactory.Options(); o2.inSampleSize = scale;

return BitmapFactory.decodeStream(new FileInputStream(f), null, o2); } catch (FileNotFoundException e) {

} return null;

} /**

* PictureToLoad类(包括图片的地址和ImageView对象) *

* @author loonggg *

*/ private class PictureToLoad {

public String url; public ImageView imageView;

public PictureToLoad(String u, ImageView i) { url = u;

imageView = i; }

} public void stopThread() {

pictureLoaderThread.interrupt(); }

// 存储下载的照片列表 class PicturesQueue {

private Stack<PictureToLoad> picturesToLoad = new Stack<PictureToLoad>(); // 删除这个ImageView的所有实例