如何获取联系人的头像:
这里采用
protected HashMap<Long, SoftReference<Bitmap>> mBitmapCache = new HashMap<Long, SoftReference<Bitmap>>(); protected HashSet<ImageView> mItemsMissingImages = new HashSet<ImageView>(); protected ImageLoaderHandler mHandler; protected ImageLoader mImageFetcher;
这边是根据photoId去数据库里查询:
public static Bitmap getContactPhoto(Context context, long photoId, BitmapFactory.Options options) {
if (photoId < 0) {
return null;
}
Cursor cursor = null;
try {
cursor = context.getContentResolver().query(
ContentUris.withAppendedId(ContactsContract.Data.CONTENT_URI, photoId),
new String[] { Photo.PHOTO }, null, null, null);
if (cursor != null && cursor.moveToFirst() && !cursor.isNull(0)) {
byte[] photoData = cursor.getBlob(0);
// Workaround for Android Issue 8488 http://code.google.com/p/android/issues/detail?id=8488
if (options == null) {
options = new BitmapFactory.Options();
}
options.inTempStorage = new byte[16 * 1024];
options.inSampleSize = 2;
return BitmapFactory.decodeByteArray(photoData, 0, photoData.length, options);
}
} catch (java.lang.Throwable error) {
} finally {
if (cursor != null) {
cursor.close();
}
}
return null;
}这个图片是压缩两倍，再转成bitmap的，我们需要考虑如果联系人非常多，我们不能把联系人的所有
头像都实时获取，再把转换得到的bitmap放到imageView中
在getView中，如果我们快速滑动列表，那么肯定不能去做获取图片的操作
if (mScrollState != OnScrollListener.SCROLL_STATE_FLING) {
sendFetchImageMessage(viewToUse);
}在检测到scrollview停顿的时候我们再去获取
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
if (SCROLL_STATE_TOUCH_SCROLL == scrollState) {
View currentFocus = getCurrentFocus();
if (currentFocus != null) {
currentFocus.clearFocus();
}
}
mScrollState = scrollState;
if (scrollState == OnScrollListener.SCROLL_STATE_FLING) {
clearImageFetching();
} else {
processMissingImageItems(view);
}
}然后图片的获取放到单独的线程中进行，通过线程池来管理:
mImageFetcher = new ImageLoader(photoId, view);
synchronized (ContactsList.this) {
if (sImageFetchThreadPool == null) {
sImageFetchThreadPool = Executors.newFixedThreadPool(3);
}
sImageFetchThreadPool.execute(mImageFetcher);
}如果在线程中获取到了bitmap那么我们通过handler来进行通知:
Message msg = new Message(); msg.what = FETCH_IMAGE_MSG; msg.obj = mImageView; mHandler.sendMessage(msg);
然后在handlermessage中进行处理:
private class ImageLoaderHandler extends Handler {
@Override
public void handleMessage(Message message) {
if (isFinishing()) {
return;
}
switch (message.what) {
case FETCH_IMAGE_MSG: {
final ImageView imageView = (ImageView) message.obj;
if (imageView == null) {
break;
}
final PhotoInfo info = (PhotoInfo) imageView.getTag();
if (info == null) {
break;
}
final long photoId = info.photoId;
if (photoId == 0) {
break;
}
SoftReference<Bitmap> photoRef = mBitmapCache.get(photoId);
if (photoRef == null) {
break;
}
Bitmap photo = photoRef.get();
if (photo == null) {
mBitmapCache.remove(photoId);
break;
}
synchronized (imageView) {
final PhotoInfo updatedInfo = (PhotoInfo) imageView
.getTag();
long currentPhotoId = updatedInfo.photoId;
if (currentPhotoId == photoId) {
imageView.setImageBitmap(photo);
mItemsMissingImages.remove(imageView);
} else {
}
}
break;
}
}
}
public void clearImageFecthing() {
removeMessages(FETCH_IMAGE_MSG);
}
}完整代码如下:
protected void setContactPhoto(Cursor cursor, final ImageView viewToUse, int column) {
long photoId = 0;
if (!cursor.isNull(column)) {
photoId = cursor.getLong(column);
}
final int position = cursor.getPosition();
viewToUse.setTag(new PhotoInfo(position, photoId));
if (photoId == 0) {
viewToUse.setImageResource(R.drawable.avatar);
} else {
Bitmap photo = null;
SoftReference<Bitmap> ref = mBitmapCache.get(photoId);
if (ref != null) {
photo = ref.get();
if (photo == null) {
mBitmapCache.remove(photoId);
}
}
if (photo != null) {
viewToUse.setImageBitmap(photo);
} else {
viewToUse.setImageResource(R.drawable.avatar);
mItemsMissingImages.add(viewToUse);
if (mScrollState != OnScrollListener.SCROLL_STATE_FLING) {
sendFetchImageMessage(viewToUse);
}
}
}
}
private void processMissingImageItems(AbsListView view) {
for (ImageView iv : mItemsMissingImages) {
sendFetchImageMessage(iv);
}
}
protected void sendFetchImageMessage(ImageView view) {
final PhotoInfo info = (PhotoInfo) view.getTag();
if (info == null) {
return;
}
final long photoId = info.photoId;
if (photoId == 0) {
return;
}
mImageFetcher = new ImageLoader(photoId, view);
synchronized (ContactsList.this) {
if (sImageFetchThreadPool == null) {
sImageFetchThreadPool = Executors.newFixedThreadPool(3);
}
sImageFetchThreadPool.execute(mImageFetcher);
}
}
public void clearImageFetching() {
synchronized (ContactsList.this) {
if (sImageFetchThreadPool != null) {
sImageFetchThreadPool.shutdownNow();
sImageFetchThreadPool = null;
}
}
mHandler.clearImageFecthing();
}
public void clearMessages() {
if (mHandler != null) {
try {
mHandler.removeCallbacksAndMessages(null);
} catch (java.lang.Throwable th) {
}
mHandler = null;
}
}
//image downloader
private class ImageLoaderHandler extends Handler {
@Override
public void handleMessage(Message message) {
if (isFinishing()) {
return;
}
switch (message.what) {
case FETCH_IMAGE_MSG: {
final ImageView imageView = (ImageView) message.obj;
if (imageView == null) {
break;
}
final PhotoInfo info = (PhotoInfo) imageView.getTag();
if (info == null) {
break;
}
final long photoId = info.photoId;
if (photoId == 0) {
break;
}
SoftReference<Bitmap> photoRef = mBitmapCache.get(photoId);
if (photoRef == null) {
break;
}
Bitmap photo = photoRef.get();
if (photo == null) {
mBitmapCache.remove(photoId);
break;
}
synchronized (imageView) {
final PhotoInfo updatedInfo = (PhotoInfo) imageView
.getTag();
long currentPhotoId = updatedInfo.photoId;
if (currentPhotoId == photoId) {
imageView.setImageBitmap(photo);
mItemsMissingImages.remove(imageView);
} else {
}
}
break;
}
}
}
public void clearImageFecthing() {
removeMessages(FETCH_IMAGE_MSG);
}
}
private class ImageLoader implements Runnable {
long mPhotoId;
private ImageView mImageView;
public ImageLoader(long photoId, ImageView imageView) {
this.mPhotoId = photoId;
this.mImageView = imageView;
}
public void run() {
if (isFinishing()) {
return;
}
if (Thread.interrupted()) {
return;
}
if (mPhotoId < 0) {
return;
}
Bitmap photo = ContactsUtils.getContactPhoto(getBaseContext(),
mPhotoId, null);
if (photo == null) {
return;
}
mBitmapCache.put(mPhotoId, new SoftReference<Bitmap>(photo));
if (Thread.interrupted()) {
return;
}
Message msg = new Message();
msg.what = FETCH_IMAGE_MSG;
msg.obj = mImageView;
mHandler.sendMessage(msg);
}
}
}//end of adapter