ListView在一些屏幕分辨率上的滾動性能

Question

我寫了一些代碼來加載JSON並將其顯示在ListView（該部分正在工作），但我的問題是，當我嘗試在某些設備上滾動我的ListView時，它有問題。特別是在Nexus S設備上，它完美的工作，但我在其他設備（例如Nexus 4，Nexus 7）上測試過，並且在這些設備上，ListView的渲染滯後不穩定（當我試着滾動它時）。

在模擬器和480x800分辨率設備上工作。

BRIgeAdapter：

package com.brige.adapter; 

import java.util.ArrayList; 
import java.util.HashMap; 

import com.brige.MainActivity; 
import com.brige.R; 
import com.brige.json.ImageLoader; 

import android.app.Activity; 
import android.content.Context; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.BaseAdapter; 
import android.widget.ImageView; 
import android.widget.TextView; 

public class BRIgeAdapter extends BaseAdapter { 
    private LayoutInflater inflater; 
    private Activity activity; 
    private ArrayList<HashMap<String, String>> data; 

    public ImageLoader imageLoader; 
    HashMap<String, String> itemList; 

    public BRIgeAdapter(Activity a, ArrayList<HashMap<String, String>> d) { 
     activity = a; 
     data = d; 
     inflater = (LayoutInflater) activity 
       .getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
     imageLoader = new ImageLoader(activity.getApplicationContext()); 
    } 

    public int getCount() { 
     return data.size(); 
    } 

    public Object getItem(int position) { 
     return null; 
    } 

    public long getItemId(int position) { 
     return 0; 
    } 



    @Override 
    public View getView(int position, View convertView, ViewGroup parent) { 
     ViewHolder holder; 
     if (convertView == null) { 
      holder = new ViewHolder(); 
      convertView = inflater.inflate(R.layout.list_row, parent, false); 

      holder.journal = (TextView) convertView 
        .findViewById(R.id.smalljournal); 
      holder.thumb_image = (ImageView) convertView 
        .findViewById(R.id.smallthumb); 
      holder.title = (TextView) convertView.findViewById(R.id.smalltitle); 
      holder.description = (TextView) convertView 
        .findViewById(R.id.smalldesc); 
      holder.statId = (TextView) convertView 
        .findViewById(R.id.smallstatID); 

      convertView.setTag(holder); 

     } else { 

      holder = (ViewHolder) convertView.getTag(); 
     } 

     itemList = data.get(position); 

     if (itemList != null) { 
      holder.journal.setText(itemList.get(MainActivity.KEY_journal)); 
      holder.statId.setText(itemList.get(MainActivity.KEY_statID)); 
      holder.journal.setTypeface(MainActivity.tf2); 

      String titleString = itemList.get(MainActivity.KEY_title); 

      holder.title.setText(titleString); 
      holder.title.setTypeface(MainActivity.tf2); 
      holder.description.setText(itemList 
        .get(MainActivity.KEY_description)); 
      holder.description.setTypeface(MainActivity.tf2); 
      imageLoader.DisplayImage(itemList.get(MainActivity.KEY_image), 
        holder.thumb_image); 

     } 

     return convertView; 
    } 

    static class ViewHolder { 
     TextView journal, title, description, statId; 
     ImageView thumb_image; 
    } 

} 

ImageLoader的：

package com.brige.json; 

import java.io.File; 
import java.io.FileInputStream; 
import java.io.FileNotFoundException; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.OutputStream; 
import java.net.HttpURLConnection; 
import java.net.URL; 
import java.util.Collections; 
import java.util.Map; 
import java.util.WeakHashMap; 
import java.util.concurrent.ExecutorService; 
import java.util.concurrent.Executors; 

import com.brige.R; 

import android.app.Activity; 
import android.content.Context; 
import android.graphics.Bitmap; 
import android.graphics.BitmapFactory; 
import android.widget.ImageView; 

public class ImageLoader { 
    MemoryCache memoryCache = new MemoryCache(); 
    FileCache fileCache; 
    private Map<ImageView, String> imageViews = Collections 
      .synchronizedMap(new WeakHashMap<ImageView, String>()); 
    ExecutorService executorService; 

    public ImageLoader(Context context) { 
     fileCache = new FileCache(context); 
     executorService = Executors.newFixedThreadPool(5); 
    } 

    final int stub_id = R.drawable.aaaaaaaaaaaaaaa; 

    public void DisplayImage(String url, ImageView imageView) { 
     imageViews.put(imageView, url); 
     Bitmap bitmap = memoryCache.get(url); 
     if (bitmap != null) 
      imageView.setImageBitmap(bitmap); 
     else { 
      queuePhoto(url, imageView); 
      imageView.setImageResource(stub_id); 
     } 
    } 

    private void queuePhoto(String url, ImageView imageView) { 
     PhotoToLoad p = new PhotoToLoad(url, imageView); 
     executorService.submit(new PhotosLoader(p)); 
    } 

    private Bitmap getBitmap(String url) { 
     File f = fileCache.getFile(url); 

     // from SD cache 
     Bitmap b = decodeFile(f); 
     if (b != null) 
      return b; 

     // from web 
     try { 
      Bitmap bitmap = null; 
      URL imageUrl = new URL(url); 
      HttpURLConnection conn = (HttpURLConnection) imageUrl 
        .openConnection(); 
      conn.setConnectTimeout(30000); 
      conn.setReadTimeout(30000); 
      conn.setInstanceFollowRedirects(true); 
      InputStream is = conn.getInputStream(); 
      OutputStream os = new FileOutputStream(f); 
      Utils.CopyStream(is, os); 
      os.close(); 
      bitmap = decodeFile(f); 
      return bitmap; 
     } catch (Throwable ex) { 
      ex.printStackTrace(); 
      if (ex instanceof OutOfMemoryError) 
       memoryCache.clear(); 
      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; 
      FileInputStream stream1 = new FileInputStream(f); 
      BitmapFactory.decodeStream(stream1, null, o); 
      stream1.close(); 

      // Find the correct scale value. It should be the power of 2. 
      final int REQUIRED_SIZE = 70; 
      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; 
      FileInputStream stream2 = new FileInputStream(f); 
      Bitmap bitmap = BitmapFactory.decodeStream(stream2, null, o2); 
      stream2.close(); 
      return bitmap; 
     } catch (FileNotFoundException e) { 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 
     return null; 
    } 

    // Task for the queue 
    private class PhotoToLoad { 
     public String url; 
     public ImageView imageView; 

     public PhotoToLoad(String u, ImageView i) { 
      url = u; 
      imageView = i; 
     } 
    } 

    class PhotosLoader implements Runnable { 
     PhotoToLoad photoToLoad; 

     PhotosLoader(PhotoToLoad photoToLoad) { 
      this.photoToLoad = photoToLoad; 
     } 

     @Override 
     public void run() { 
      try { 
       if (imageViewReused(photoToLoad)) 
        return; 
       Bitmap bmp = getBitmap(photoToLoad.url); 
       memoryCache.put(photoToLoad.url, bmp); 
       if (imageViewReused(photoToLoad)) 
        return; 
       BitmapDisplayer bd = new BitmapDisplayer(bmp, photoToLoad); 
       Activity a = (Activity) photoToLoad.imageView.getContext(); 
       a.runOnUiThread(bd); 
      } catch (Throwable th) { 
       th.printStackTrace(); 
      } 
     } 
    } 

    boolean imageViewReused(PhotoToLoad photoToLoad) { 
     String tag = imageViews.get(photoToLoad.imageView); 
     if (tag == null || !tag.equals(photoToLoad.url)) 
      return true; 
     return false; 
    } 

    // Used to display bitmap in the UI thread 
    class BitmapDisplayer implements Runnable { 
     Bitmap bitmap; 
     PhotoToLoad photoToLoad; 

     public BitmapDisplayer(Bitmap b, PhotoToLoad p) { 
      bitmap = b; 
      photoToLoad = p; 
     } 

     public void run() { 
      if (imageViewReused(photoToLoad)) 
       return; 
      if (bitmap != null) 
       photoToLoad.imageView.setImageBitmap(bitmap); 
      else 
       photoToLoad.imageView.setImageResource(stub_id); 
     } 
    } 

    public void clearCache() { 
     memoryCache.clear(); 
     fileCache.clear(); 
    } 

} 

Answer 1

嘗試更改庫/執行你的ImageLoader的的。我可以推薦UniversalImageLoader。