Test environment for adnroid more than 2.1.
1.androidmanifest.xml Permission Configuration：
To add Internet access rights:
Copy Code code as follows:
<uses-permission android:name= "Android.permission.INTERNET"/>
2. Asynchronous Picture class Imagedownloadtask
Copy Code code as follows:
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;
/***
* Here to get the resolution size of the phone
* */
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;
@Override
Protected Bitmap doinbackground (Object ... params) {
TODO auto-generated Method Stub
Bitmap 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 ();
}
}
/**
* Get online pictures via URL. such as: yun_qi_img/www.sexyxxx.com
* */
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);
These 3 sentences are to handle the image overflow begin (If the overflow is not needed to deal with the opts.insamplesize=1 directly;)
Opts.injustdecodebounds = true;
Bitmapfactory.decodebytearray (bytes, 0, Bytes.length, opts);
Opts.insamplesize = Computesamplesize (opts,-1, displaypixels);
End
Opts.injustdecodebounds = false;
bmp = Bitmapfactory.decodebytearray (bytes, 0, Bytes.length, opts);
return BMP;
}
/**
* Data flow into btyle[] Array
* */
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;
}
/****
* Processing picture bitmap size exceeds VM budget (out of Memory memory overflow)
*/
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;
}
}
}
3. Test Call Code：
Copy Code code as follows:
@Override
public void OnCreate (Bundle savedinstancestate) {
Super.oncreate (savedinstancestate);
Setcontentview (R.layout.main);
Imagedownloadtask imgtask =new imagedownloadtask ();
/** here is to get the resolution of the phone screen to handle the picture overflow problem. begin*/
Displaymetrics dm = new Displaymetrics ();
Getwindowmanager (). Getdefaultdisplay (). Getmetrics (DM);
Imgtask.setdisplaywidth (Dm.widthpixels);
Imgtask.setdisplayheight (Dm.heightpixels);
End
ImageView imageview_test= (ImageView) Findviewbyid (r.id.imageview_test);
Imgtask.execute ("Yun_qi_img/201201031116491.jpg", imageview_test);
}
4. Summary：
Mainly through extends Asynctask<object, Object, bitmap> to achieve asynchronous.
Picture out of Memory memory overflow This operation, in practical applications should be considered calm extraction. It's easy to put in here for convenience. Overflow processing is actually to obtain the device resolution to compress the picture.
