当使用asynctask加载图像时，Android listview中的行为异常

Fergers 发表于 Dev

费格斯

我希望有人能帮助我解决我遇到的ListView问题。昨天我一直在用铁墙砸头，因为我不知道是什么问题。原来不是我的项目使它变得更加困难。

我有一个列表视图，我想在其中加载联系人行。在每行的左侧，我想（向下）加载图像异步。为此，我正在使用以下ArrayAdapter和ListItem布局，请忽略不推荐使用的函数。

这是一个视频http://www.youtube.com/watch?v=aMqI9_y3pag&feature=youtu.be

问题：每当列表加载时，所有图像就会相互加载，然后将蜜蜂放置在正确的位置。它看起来确实有故障，即使响应速度很快，而且看起来也很恐怖。我在arrayadapter中添加了一个计数器，以计算getView被调用的时间。

没有异步图像的4个项目-大约 38时代
带有异步图像的4个项目-大约 180时代

希望有人可以帮助我！

阵列适配器

    public class ChatContactListArrayAdapter extends ArrayAdapter<ChatContact>{

    private Context context;
    private ArrayList<ChatContact> chatContacts;

    public static DiskImageLoaderHelper diskImageLoader;

    public int count = 0;

    public ChatContactListArrayAdapter(Context context, int resource, ArrayList<ChatContact> chatContacts) {
        super(context, resource, chatContacts);

        this.chatContacts = chatContacts;
        this.context = context;
        diskImageLoader = new DiskImageLoaderHelper(context, "ChatListImages", (1024 * 1024 * 10), CompressFormat.JPEG, 90);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        count++;
        Log.e(DebugHelper.TAG_DEBUG, "Count: " + count + " Position: " + position);
        ChatContact chatContact = chatContacts.get(position);

        View view = convertView;

        if (view == null) {
            LayoutInflater inflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            view = inflater.inflate(R.layout.chat_contact_list_row, null);
        }

        ImageView contactImageView = (ImageView) view.findViewById(R.id.contact_image);
        if (chatContact.Picture != null) {
            BitmapWorkerTask bitmapWorker = new BitmapWorkerTask(contactImageView, diskImageLoader);
            bitmapWorker.execute(chatContact.Picture);
        } else {
            contactImageView.setVisibility(View.INVISIBLE);
        }

        TextView fromTextView = (TextView) view.findViewById(R.id.fromName);
        fromTextView.setText(chatContact.Name);

        Boolean l_blToMe = false;
        if (chatContact.From == chatContact.Id) {
            l_blToMe = true;
        }

        LinearLayout chatContactRow = (LinearLayout) view.findViewById(R.id.chatContactRow);
        ImageView imageViewStatusMessage = (ImageView) view.findViewById(R.id.lastMessageStatusImg);

        TextView lastMessage = (TextView) view.findViewById(R.id.lastMessage);
        if (CommonUtilities.isNullOrEmpty(chatContact.Message) && !CommonUtilities.isNullOrEmpty(chatContact.MessageId)) {
            lastMessage.setText("<afbeelding>");
        } else {
            lastMessage.setText(chatContact.Message);
        }

        imageViewStatusMessage.setImageResource(0);

        if (!CommonUtilities.isNullOrEmpty(chatContact.Received)) {
            imageViewStatusMessage.setImageDrawable(context.getResources().getDrawable(R.drawable.chat_double_check));
            chatContactRow.setBackgroundColor(Color.parseColor("#F2F2F2"));
            lastMessage.setTypeface(null, Typeface.NORMAL);
        } else if (!CommonUtilities.isNullOrEmpty(chatContact.Sent) && !l_blToMe) {
            imageViewStatusMessage.setImageDrawable(context.getResources().getDrawable(R.drawable.chat_single_check));
            chatContactRow.setBackgroundColor(Color.parseColor("#F2F2F2"));
            lastMessage.setTypeface(null, Typeface.NORMAL);
        } else if (!CommonUtilities.isNullOrEmpty(chatContact.Sent) && l_blToMe) {
            imageViewStatusMessage.setImageDrawable(context.getResources().getDrawable(R.drawable.chat_arrow));
            chatContactRow.setBackgroundColor(Color.parseColor("#F4E0CC"));
            lastMessage.setTypeface(null, Typeface.BOLD);
        } else {
            imageViewStatusMessage.setVisibility(View.INVISIBLE);
        }

        TextView receivedDate = (TextView) view.findViewById(R.id.receivedDate);

        if (!CommonUtilities.isNullOrEmpty(chatContact.Sent) && CommonUtilities.isNullOrEmpty(chatContact.Received)) {
            try {
                SimpleDateFormat l_dbDateFormatter = new SimpleDateFormat("yyyyMMddHHmmss");
                Date l_dOrgDate = (Date) l_dbDateFormatter.parse(chatContact.Sent);
                SimpleDateFormat l_showDateFormatter = new SimpleDateFormat("dd-MM-yyyy HH:mm");

                String newDateStr = l_showDateFormatter.format(l_dOrgDate);
                receivedDate.setText(newDateStr);
            } catch (ParseException e) {
                Log.e(DebugHelper.TAG_ERROR, "ChatContactListAdapter::" + e.toString());
//              ACRA.getErrorReporter().handleSilentException(e);
            }
        } else if (!CommonUtilities.isNullOrEmpty(chatContact.Received)) {
            try {
                SimpleDateFormat l_dbDateFormatter = new SimpleDateFormat(
                        "yyyyMMddHHmmss");
                Date l_dOrgDate = (Date) l_dbDateFormatter.parse(chatContact.Received);
                SimpleDateFormat l_showDateFormatter = new SimpleDateFormat(
                        "dd-MM-yyyy HH:mm");

                String newDateStr = l_showDateFormatter.format(l_dOrgDate);
                receivedDate.setText(newDateStr);
            } catch (ParseException e) {
                Log.e(DebugHelper.TAG_ERROR, "ChatContactListAdapter::" + e.toString());
//              ACRA.getErrorReporter().handleSilentException(e);
            }
        } else {
            receivedDate.setVisibility(View.INVISIBLE);
        }

        return view;
    }

    @Override
    public void clear() {
        count = 0;
        super.clear();
    }

    class BitmapWorkerTask extends AsyncTask<String, Void, Drawable> {

        private final WeakReference<ImageView> contactImageView;
        private DiskImageLoaderHelper diskImageLoader;

        public BitmapWorkerTask(ImageView imageView, DiskImageLoaderHelper diskImageLoader) {
            this.contactImageView = new WeakReference<ImageView>(imageView);
            this.diskImageLoader = diskImageLoader;
        }

        @Override
        protected Drawable doInBackground(String... params) {
            String imageUrl = params[0];
            Bitmap bitmap = null;
            if (!diskImageLoader.containsKey(CommonUtilities.filePathToCacheKey(imageUrl, false)) || false) {
                bitmap = CommonUtilities.getCroppedBitmap(CommonUtilities.createBitmapFromImageLocation(CommonUtilities.mStrBasePath + imageUrl), 50);
                if(bitmap != null) {
                    diskImageLoader.put(CommonUtilities.filePathToCacheKey(imageUrl, true), bitmap);
                }
            } else {
                bitmap = diskImageLoader.getBitmap(CommonUtilities.filePathToCacheKey(imageUrl, false));
            }

            return new BitmapDrawable(context.getResources(), bitmap);
        }

        @Override
        protected void onPostExecute(Drawable drawable) {
            ImageView view = contactImageView.get();
            if (view != null && drawable != null) {
                view.setBackgroundDrawable(drawable);
//              contactImageView.setImageBitmap(bitmap);
                view.setImageDrawable(context.getResources().getDrawable(R.drawable.image_round_overlay_grey));
            }
        }
    }
}

ListViewItem布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@drawable/chat_contact_list_selector"
    android:orientation="horizontal"
    android:id="@+id/chatContactRow" >

    <ImageView
        android:id="@+id/contact_image"
        android:layout_width="55dp"
        android:layout_height="55dp"
        android:layout_marginBottom="10dp"
        android:layout_marginTop="10dp"
        android:layout_marginLeft="5dp"
        android:src="@drawable/image_round_overlay_grey"/>

    <LinearLayout
        android:id="@+id/TextualHolder"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical" 
        android:baselineAligned="false">

        <RelativeLayout 
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal" 
            android:baselineAligned="false">
            <TextView
                android:id="@+id/fromName"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginLeft="10dip"
                android:layout_marginTop="10dp"
                android:paddingBottom="10dip"
                android:textColor="#222222"
                android:ellipsize="end"
                android:singleLine="true"
                android:textSize="18sp" />

            <TextView
                android:id="@+id/receivedDate"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginRight="15dp"
                android:layout_marginTop="10dp"
                android:layout_alignParentRight="true"
                android:paddingBottom="10dip"
                android:textColor="#777777"
                android:textSize="10sp"
                android:textStyle="bold" />
        </RelativeLayout>

        <LinearLayout
            android:id="@+id/statusMessageHolder"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            android:layout_marginLeft="10dip"
            android:paddingBottom="10dip" >

            <ImageView
                android:id="@+id/lastMessageStatusImg"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center_vertical" />

            <TextView
                android:id="@+id/lastMessage"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:textColor="#777777"
                android:textSize="15sp"
                android:ellipsize="end"
                android:singleLine="true"
                android:textStyle="bold"/>
        </LinearLayout>
    </LinearLayout>
</LinearLayout>

在我的sherlockFragment中创建

@Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        context = getActivity().getApplicationContext();

        mLvContactList = (ListView) getView().findViewById(R.id.listContacts);
        if(mDbDataBase == null)
            mDbDataBase = nl.w3s.hulpverlener.JohelpenApplication.mDbDataBase;
        if(mCurDB == null)
            mCurDB = nl.w3s.hulpverlener.JohelpenApplication.mCurDB;

        mCursor = mCurDB.query(mTblChatContacts.mTable, mDbDataBase.dbFieldsToString(mTblChatContacts.mFields), null, null, null, null, null);
        chatContacts = CommonUtilities.getContactsFromCursor(mCursor);
        mCursor.close();

        chatContactArrayAdapter = new ChatContactListArrayAdapter(getActivity(), R.layout.chat_contact_list_row, chatContacts);
        mLvContactList.setAdapter(chatContactArrayAdapter);

        mLvContactList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                    @Override
                    public void onItemClick(AdapterView<?> parent,
                            final View view, int position, long id) {

                        ChatContact chatContact = (ChatContact) parent.getItemAtPosition(position);
                        ChatFragment chatFragment = new ChatFragment(chatContact.Id);
                        mMainObject.switchContent(chatFragment, true);
                    }
                });

        getSherlockActivity().getSupportActionBar().setIcon(R.drawable.icon_ab_chat);
        getSherlockActivity().getSupportActionBar().setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
        MainActivity.mMenuLayout = -1;
        getSherlockActivity().invalidateOptionsMenu();
        setStatusMessage();

        mMainObject.setTitle(mTitle);
    }

用户名

实际上，主要问题是您没有在自定义适配器的方法中的大多数条件语句中添加else条件语句。ifgetView()

喜欢，

放在else这里

if (chatContact.Picture != null) {
        BitmapWorkerTask bitmapWorker = new BitmapWorkerTask(contactImageView, diskImageLoader);
        bitmapWorker.execute(chatContact.Picture);
}
else
{
        contactImageView.setImageResource(R.id.icon); // only for your reference.. add default image
}

else在您的所有if-else if语句中添加语句以获取列表项行视图。要么使它们不可见，要么分配空白文本或默认图像。

更新：我怀疑这种情况是由于列表行的引用视图。

删除此代码，

 View view = convertView;

 if (view == null) {
     LayoutInflater inflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
     view = inflater.inflate(R.layout.chat_contact_list_row, null);
 }

随便用

LayoutInflater inflater = (LayoutInflater)getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
view = inflater.inflate(R.layout.chat_contact_list_row, null);

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