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我新在Android上我想在後臺設置的圖像是從URL獲取..我現在用ImageLoader的類 請幫我設置圖像視圖背景..如何設置背景圖像視
這是我的圖像裝載機類
public class ImageLoader {
// the simplest in-memory cache implementation. This should be replaced with
// something like SoftReference or BitmapOptions.inPurgeable(since 1.6)
private HashMap<String, Bitmap> cache = new HashMap<String, Bitmap>();
private File cacheDir;
static ArrayList<String> img_path = new ArrayList<String>();
static String sd_card_folder_name = "ImageLoader";
static int width;
public ImageLoader(Context context, Activity acc) {
// Make the background thead low priority. This way it will not affect
// the UI performance
photoLoaderThread.setPriority(Thread.NORM_PRIORITY - 1);
DisplayMetrics displaymetrics = new DisplayMetrics();
acc.getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
width = displaymetrics.widthPixels;
Log.d("width", "width = " + width);
cache.clear();
img_path = new ArrayList<String>();
// Find the dir to save cached images
if (android.os.Environment.getExternalStorageState().equals(
android.os.Environment.MEDIA_MOUNTED))
cacheDir = new File(android.os.Environment
.getExternalStorageDirectory(), sd_card_folder_name);
else
cacheDir = context.getCacheDir();
if (!cacheDir.exists())
cacheDir.mkdirs();
}
final int stub_id = R.drawable.loader;
public void DisplayImage(String url, Activity activity, ImageView imageView) {
try {
String filename = String.valueOf(url.hashCode());
File[] file_array = cacheDir.listFiles();
for (int i = 0; i < file_array.length; i++) {
img_path.add(file_array[i].getName());
}
if (img_path.contains(filename)) {
imageView.setImageBitmap(BitmapFactory
.decodeFile("/mnt/sdcard/" + sd_card_folder_name + "/"
+ filename));
} else {
if (cache.containsKey(url)) {
imageView.setImageBitmap(cache.get(url));
} else {
queuePhoto(url, activity, imageView, filename);
imageView.setImageResource(stub_id);
}
}
} catch (Exception e) {
// TODO: handle exception
}
}
private void queuePhoto(String url, Activity activity, ImageView imageView, String _name) {
// This ImageView may be used for other images before. So there may be
// some old tasks in the queue. We need to discard them.
photosQueue.Clean(imageView);
PhotoToLoad p = new PhotoToLoad(url, imageView, _name);
synchronized (photosQueue.photosToLoad) {
photosQueue.photosToLoad.push(p);
photosQueue.photosToLoad.notifyAll();
}
// start thread if it's not started yet
if (photoLoaderThread.getState() == Thread.State.NEW)
photoLoaderThread.start();
}
private Bitmap getBitmap(String url) {
// I identify images by hashcode. Not a perfect solution, good for the
// demo.
if (url != null && !(url.equals(""))) {
String filename = String.valueOf(url.hashCode());
File f = new File(cacheDir, filename);
/*
* // from SD cache Bitmap b = decodeFile(f); if (b != null) return
* b;
*/
// from web
try {
Bitmap bitmap = null;
InputStream is = new URL(url).openStream();
OutputStream os = new FileOutputStream(f);
Utils.CopyStream(is, os);
os.close();
bitmap = decodeFile(f);
return bitmap;
} catch (Exception ex) {
ex.printStackTrace();
return null;
}
}
return null;
}
// decodes image and scales it to reduce memory consumption
private Bitmap decodeFile(File f) {
try {
// decode image size
BitmapFactory.Options o = new BitmapFactory.Options();
o.inJustDecodeBounds = true;
BitmapFactory.decodeStream(new FileInputStream(f), null, o);
// Find the correct scale value. It should be the power of 2.
final int REQUIRED_SIZE=300;
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;
}
// decode with inSampleSize
BitmapFactory.Options o2 = new BitmapFactory.Options();
o2.inSampleSize = scale;
return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
} catch (FileNotFoundException e) {
}
return null;
}
// Task for the queue
private class PhotoToLoad {
public String url;
public ImageView imageView;
public String _name;
public PhotoToLoad(String u, ImageView i, String n) {
url = u;
imageView = i;
_name = n;
}
}
PhotosQueue photosQueue = new PhotosQueue();
public void stopThread() {
photoLoaderThread.interrupt();
}
// stores list of photos to download
class PhotosQueue {
private Stack<PhotoToLoad> photosToLoad = new Stack<PhotoToLoad>();
// removes all instances of this ImageView
public void Clean(ImageView image) {
for (int j = 0; j < photosToLoad.size();) {
if (photosToLoad.get(j).imageView == image)
photosToLoad.remove(j);
else
++j;
}
}
}
class PhotosLoader extends Thread {
public void run() {
try {
while (true) {
// thread waits until there are any images to load in the
// queue
if (photosQueue.photosToLoad.size() == 0)
synchronized (photosQueue.photosToLoad) {
photosQueue.photosToLoad.wait();
}
if (photosQueue.photosToLoad.size() != 0) {
PhotoToLoad photoToLoad;
synchronized (photosQueue.photosToLoad) {
photoToLoad = photosQueue.photosToLoad.pop();
}
Bitmap bmp = getBitmap(photoToLoad.url);
cache.put(photoToLoad.url, bmp);
Object tag = photoToLoad.imageView.getTag();
String FileName = photoToLoad._name;
if (FileName != null
&& ((String) FileName).equals(photoToLoad._name)) {
BitmapDisplayer bd = new BitmapDisplayer(bmp,
photoToLoad.imageView, FileName);
Activity a = (Activity) photoToLoad.imageView
.getContext();
a.runOnUiThread(bd);
}
}
if (Thread.interrupted())
break;
}
} catch (InterruptedException e) {
// allow thread to exit
}
}
}
PhotosLoader photoLoaderThread = new PhotosLoader();
// Used to display bitmap in the UI thread
class BitmapDisplayer implements Runnable {
Bitmap bitmap;
ImageView imageView;
String file_name;
public BitmapDisplayer(Bitmap b, ImageView i, String _name) {
bitmap = b;
imageView = i;
file_name = _name;
}
public void run() {
if (bitmap != null) {
load_full_image(imageView, file_name, bitmap);
} else
imageView.setImageResource(stub_id);
}
}
private Runnable mMyRunnable = new Runnable() {
@Override
public void run() {
}
};
public void load_full_image(ImageView img, String _name, Bitmap btmp) {
img_path = new ArrayList<String>();
File[] file_array = cacheDir.listFiles();
for (int i = 0; i < file_array.length; i++) {
img_path.add(file_array[i].getName());
}
if (img_path.contains(_name)) {
img.setImageBitmap(BitmapFactory
.decodeFile("/mnt/sdcard/" + sd_card_folder_name + "/"
+ _name));
} else {
img.setImageBitmap(btmp);
}
}
public void clearCache() {
// clear memory cache
cache.clear();
// clear SD cache
File[] files = cacheDir.listFiles();
for (File f : files)
f.delete();
}
這是我的活動我在哪裏獲取圖像在imagview
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.userprofile);
Button addfrnd=(Button)findViewById(R.id.addfrnd);
ImageView image = (ImageView) findViewById(R.id.imageView1);
UserModel user = (UserModel) getIntent().getSerializableExtra("User");
UserByIdModel tempuser = (UserByIdModel) getIntent().getSerializableExtra("UserById");
String UserId=String.valueOf(tempuser.getUser_Id());
String image_url=tempuser.getUser_Image();
int loader = R.drawable.loader;
ImageLoader imgLoader = new ImageLoader(getApplicationContext(),
UserByIdProfile.this);
image.setTag(image_url);
// whenever you want to load an image from url
// call DisplayImage function
// url - image url to load
// loader - loader image, will be displayed before getting image
// image - ImageView
imgLoader.DisplayImage(image_url, UserByIdProfile.this, image);
請參閱http://stackoverflow.com/questions/22322428/unable-to-set-image-view-background-image-using-universal-image-loader –