import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.widget.ImageView;public class ImageDownloadTask extends AsyncTask<Object, Object, Bitmap> {private ImageView imageView = null;/**** 这里获取到手机的分辨率大小* */public  void setDisplayWidth(int width) {_displaywidth = width;}public  int getDisplayWidth() {return _displaywidth;}public  void setDisplayHeight(int height) {_displayheight = height;}public  int getDisplayHeight() {return _displayheight;}public  int getDisplayPixels() {return _displaypixels;}private  int _displaywidth = 480;private  int _displayheight = 800;private  int _displaypixels = _displaywidth * _displayheight;@Overrideprotected Bitmap doInBackground(Object... params) {// TODO Auto-generated method stubBitmap bmp = null;imageView = (ImageView) params[1];try {String url = (String) params[0];bmp = getBitmap(url, _displaypixels,true);} catch (Exception e) {return null;}return bmp;}protected void onPostExecute(Bitmap result) {if (imageView != null&&result!=null) {imageView.setImageBitmap(result);if (null != result && result.isRecycled() == false)System.gc();}}/*** 通过URL获得网上图片。如:http://www.xxxxxx.com/xx.jpg* */public Bitmap getBitmap(String url, int displaypixels, Boolean isBig) throws MalformedURLException, IOException {Bitmap bmp = null;BitmapFactory.Options opts = new BitmapFactory.Options();InputStream stream = new URL(url).openStream();byte[] bytes = getBytes(stream);//这3句是处理图片溢出的begin( 如果不需要处理溢出直接 opts.inSampleSize=1;)opts.inJustDecodeBounds = true;BitmapFactory.decodeByteArray(bytes, 0, bytes.length, opts);opts.inSampleSize = computeSampleSize(opts, -1, displaypixels);//endopts.inJustDecodeBounds = false;bmp = BitmapFactory.decodeByteArray(bytes, 0, bytes.length, opts);return bmp;}/*** 数据流转成btyle[]数组* */private byte[] getBytes(InputStream is) {ByteArrayOutputStream baos = new ByteArrayOutputStream();byte[] b = new byte[2048];int len = 0;try {while ((len = is.read(b, 0, 2048)) != -1) {baos.write(b, 0, len);baos.flush();}} catch (IOException e) {e.printStackTrace();}byte[] bytes = baos.toByteArray();return bytes;}/*****    处理图片bitmap size exceeds VM budget （Out Of Memory 内存溢出）*/private int computeSampleSize(BitmapFactory.Options options,int minSideLength, int maxNumOfPixels) {int initialSize = computeInitialSampleSize(options, minSideLength,maxNumOfPixels);int roundedSize;if (initialSize <= 8) {roundedSize = 1;while (roundedSize < initialSize) {roundedSize <<= 1;}} else {roundedSize = (initialSize + 7) / 8 * 8;}return roundedSize;}private int computeInitialSampleSize(BitmapFactory.Options options,int minSideLength, int maxNumOfPixels) {double w = options.outWidth;double h = options.outHeight;int lowerBound = (maxNumOfPixels == -1) ? 1 : (int) Math.ceil(Math.sqrt(w * h / maxNumOfPixels));int upperBound = (minSideLength == -1) ? 128 : (int) Math.min(Math.floor(w / minSideLength), Math.floor(h / minSideLength));if (upperBound < lowerBound) {return lowerBound;}if ((maxNumOfPixels == -1) && (minSideLength == -1)) {return 1;} else if (minSideLength == -1) {return lowerBound;} else {return upperBound;}}
}

@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);ImageDownloadTask imgtask =new ImageDownloadTask();/**这里是获取手机屏幕的分辨率用来处理 图片 溢出问题的。begin*/DisplayMetrics dm = new DisplayMetrics();getWindowManager().getDefaultDisplay().getMetrics(dm);imgtask.setDisplayWidth(dm.widthPixels);imgtask.setDisplayHeight(dm.heightPixels);//endImageView imageView_test= (ImageView)findViewById(R.id.imageView_test);imgtask.execute("http://pic.qukantu.com/big/7515/201201031116491.jpg",imageView_test);}