【发布时间】：2017-10-28 05:14:56
【问题描述】：
我正在尝试制作一个文件浏览器。我实现了这一切，只是我的图像缩略图加载太慢了。所以我读到我必须转移到 asynctask，然后在执行后更新 ui。在运行 asynctask 之前，我为所有文件提供了默认缩略图。在 asynctask 中，我将位置作为参数，因为我使用它们设置标签。然后我使用该位置检查文件。如果那是图像或视频，我会为它创建一个位图。在后期执行中，我创建了一个新的查看器并使用 getTag(position) 为其分配相同的标签。然后我使用 setBitmapImage 分配位图。问题：即使不是图像/视频的文件，缩略图也会发生变化/闪烁。
到目前为止我尝试过的事情：
a)updating of Image Thumbnails using AsyncTask for Android ListView not coming proper
b)Android ListView updating of Image Thumbnails using AsyncTask Causes View recycling
这是我的 getView 代码：
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
File file=new File(String.valueOf(filenames[position]));
if(file.isDirectory()){
img=R.drawable.folder;
}
else{
img=getImage(filenames[position]);
}
ViewHolder viewHolder = null;
if (convertView == null) {
LayoutInflater inflator = LayoutInflater.from(getContext());
convertView = inflator.inflate(R.layout.list_item, null);
viewHolder = new ViewHolder();
viewHolder.tv = (TextView) convertView.findViewById(R.id.textView1);
viewHolder.cb = (CheckBox) convertView.findViewById(R.id.checkBox1);
viewHolder.iv= (ImageView)convertView.findViewById(R.id.imageView);
viewHolder.cb.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
int getPosition = (Integer) buttonView.getTag(); // Here we get the position that we have set for the checkbox using setTag.
myList.get(getPosition).setSelected(buttonView.isChecked()); // Set the value of checkbox to maintain its state.
}
});
convertView.setTag(viewHolder);
convertView.setTag(R.id.textView1, viewHolder.tv);
convertView.setTag(R.id.checkBox1, viewHolder.cb);
convertView.setTag(R.id.checkBox1, viewHolder.iv);
}
else {
viewHolder = (ViewHolder) convertView.getTag();
}
viewHolder.iv.getLayoutParams().height = 80;
viewHolder.iv.getLayoutParams().width = 80;
viewHolder.cb.setTag(position);
final ViewHolder ViewHolder= viewHolder;
ViewHolder.iv.setImageResource(img);
ViewHolder.tv.setText(myList.get(position).getName());
ViewHolder.cb.setChecked(myList.get(position).isSelected());
final View finalConvertView = convertView;
class myTask extends AsyncTask<Integer,Void,Bitmap>{
int pos;
public myTask(int pos){
this.pos=pos;
}
@Override
protected Bitmap doInBackground(Integer... params) {
Bitmap thumb=null;
if((String.valueOf(filenames[pos])).contains(".jpeg")||String.valueOf(filenames[pos]).contains(".jpg")||String.valueOf(filenames[pos]).contains(".png")||String.valueOf(filenames[pos]).contains(".bmp")||String.valueOf(filenames[pos]).contains(".webp")||String.valueOf(filenames[pos]).contains(".gif")){
thumb = ThumbnailUtils.extractThumbnail(BitmapFactory.decodeFile(String.valueOf(filenames[pos])), 64, 64);
}
else if((String.valueOf(filenames[pos])).contains(".mp4")||String.valueOf(filenames[pos]).contains(".mkv")||String.valueOf(filenames[pos]).contains(".webm")||String.valueOf(filenames[pos]).contains(".3gp")||String.valueOf(filenames[pos]).contains(".3gpp")){
thumb=ThumbnailUtils.createVideoThumbnail(filenames[pos].getPath(), MediaStore.Video.Thumbnails.MINI_KIND);
}
return thumb;
}
@Override
protected void onPostExecute(Bitmap thumb){
if(isCancelled()){
return;
}
ViewHolder v= (ViewHolder) finalConvertView.getTag(pos);
if((String.valueOf(filenames[pos])).contains(".jpeg")||String.valueOf(filenames[pos]).contains(".jpg")||String.valueOf(filenames[pos]).contains(".png")||String.valueOf(filenames[pos]).contains(".bmp")||String.valueOf(filenames[pos]).contains(".webp")||String.valueOf(filenames[pos]).contains(".gif")){
v.iv.setImageBitmap(thumb);
}
else if((String.valueOf(filenames[pos])).contains(".mp4")||String.valueOf(filenames[pos]).contains(".mkv")||String.valueOf(filenames[pos]).contains(".webm")||String.valueOf(filenames[pos]).contains(".3gp")||String.valueOf(filenames[pos]).contains(".3gpp")){
v.iv.setImageBitmap(thumb);
}
}
}
myTask m=new myTask(position);
m.execute();
return convertView;
}
【问题讨论】：
标签： android image listview android-asynctask