Android：在gridview中重用嵌入式视图[解决方案已发布]

2019年8月3日 88次阅读

我正在尝试重用一个在其中包含图像和textview的framelayout,但我不认为我这样做是正确的.代码工作,显示正确,但性能很差,我相信这是因为每次适配器返回项目位置时我都会创建一个新的
ImageView和TextView.

有人能告诉我如何在不创建新对象的情况下重用嵌入式ImageView(称为i)和TextView(称为t)吗？我是Java新手,这是我尝试构建Android应用程序.

        public View getView(int position, View convertView, ViewGroup parent) {  

            FrameLayout F;
            FrameLayout ImageBorder;
            FrameLayout TextBG;

            ImageView i;
            TextView t;

            if(convertView == null) {
                F = new FrameLayout(mContext);

            } else {
                F = (FrameLayout) convertView;
            }

            ImageBorder = new FrameLayout(F.getContext());
            FrameLayout.LayoutParams params1 = new FrameLayout.LayoutParams(FrameLayout.LayoutParams.FILL_PARENT,300,Gravity.BOTTOM);
            ImageBorder.setLayoutParams(params1);

            i = new ImageView(F.getContext()); 
            TextBG = new FrameLayout(F.getContext());
            t = new TextView(F.getContext());

            F.setBackgroundColor(Color.BLACK);
            ImageBorder.setPadding(2, 2, 2, 2);
            ImageBorder.setBackgroundColor(Color.BLACK);

            FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(FrameLayout.LayoutParams.FILL_PARENT,40,Gravity.BOTTOM);

            TextBG.setLayoutParams(params);
            TextBG.setBackgroundColor(Color.BLACK);
            TextBG.setAlpha(.6f);

            t.setLayoutParams(params);

            t.setGravity(Gravity.CENTER_VERTICAL);

            String pathToPhoto = FileList.get(position).toString();
            String fileDescription = pathToPhoto.replaceAll("/mnt/external1/PaliPhotography/","");

            fileDescription = fileDescription.replaceAll(".jpg","");
            fileDescription = fileDescription.toUpperCase();


            Bitmap bm = Cache.getCacheFile("thumb",pathToPhoto);

             if (bm == null) {
                ImageDownloader downloader = new ImageDownloader(i);
                downloader.execute("thumb", pathToPhoto, "400", "400");
             } else {

                i.setImageBitmap(bm);
                i.setScaleType(ImageView.ScaleType.CENTER_CROP);

                t.setTextAppearance(getApplicationContext(), android.R.style.TextAppearance_Large);
                t.setText(" " + fileDescription);

             }

             ImageBorder.addView(i);
             ImageBorder.addView(TextBG);
             ImageBorder.addView(t);

             F.addView(ImageBorder);

             return F;  

        }  
    }

先感谢您！

[编辑]

—————————解决方案———————- ——————————-

以下是我根据以下反馈实施的解决方案！谢谢！

        public View getView(int position, View convertView, ViewGroup parent) {  

            View ReturnThisView;
            ViewHolder holder;

            LayoutInflater inflater;
            holder = new ViewHolder();

            if(convertView == null) {
                inflater = (LayoutInflater)mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                ReturnThisView = inflater.inflate(R.layout.imagecell, null);
                ReturnThisView.setTag(holder);
            } else {
                ReturnThisView = convertView;
            }

            holder.TextDescription = (TextView) ReturnThisView.findViewById(R.id.PhotoDesc);
            holder.ImageThumbnail = (ImageView) ReturnThisView.findViewById(R.id.Thumbnail);

            String pathToPhoto = FileList.get(position).toString();
            String fileDescription = pathToPhoto.replaceAll("/mnt/external1/PaliPhotography/","");

            fileDescription = fileDescription.replaceAll(".jpg","");
            fileDescription = fileDescription.toUpperCase();

            Bitmap bm = Cache.getCacheFile("thumb",pathToPhoto);

             if (bm == null) {
                ImageDownloader downloader = new ImageDownloader(holder.ImageThumbnail);
                downloader.execute("thumb", pathToPhoto, "400", "400");
             } else {

                holder.ImageThumbnail.setImageBitmap(bm);
                holder.ImageThumbnail.setScaleType(ImageView.ScaleType.CENTER_CROP);

                holder.TextDescription.setTextAppearance(getApplicationContext(), android.R.style.TextAppearance_Large);
                holder.TextDescription.setText(" " + fileDescription);

             }

             return ReturnThisView;
        }  
    }

    static class ViewHolder {
    TextView TextDescription;
    ImageView ImageThumbnail;
}

最佳答案 >而不是为每个元素动态创建View,而是创建一个XML布局文件,比如row.xml.

>如果通过使用inflater检测到convertView == null为新行充气

>使用View#findViewById找到TextView和ImageView

>创建一个Holder对象,它有助于保存对新发现的TextView和ImageView的引用

>将持有者保存为标记,以便convertView.setTag(holder)

>对于现有的convertView,通过执行holder = convertView.getTag()查找Holder对象

>为这两个保存的对象设置文本和图像,例如holder.txt.setText( “富”)

>重新使用膨胀行的实例,Android适配器将完成其余工作

可以说甚至对于你的代码你可以查看初始化和布局一次并使用Holder模式来避免重新初始化元素但我认为XML会给你更好的体验

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