3

I created a ListView using an ArrayAdapter that implements the getView() method in this way:

public View getView(int position, View convertView, ViewGroup parent) {
    View rowView = convertView;
    if(rowView ==null){
    LayoutInflater inflater = (LayoutInflater) context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);         
    rowView = inflater.inflate(R.layout.rowlayout_member, parent, false);
            }
    TextView textView = (TextView) rowView.findViewById(R.id.label);
    TextView textView1 = (TextView) rowView.findViewById(R.id.label1);
    ImageView imageView = (ImageView) rowView.findViewById(R.id.icon);
    textView.setText(values[position]);
    textView1.setText(surname[position]);

    String s = values[position];
    if(foto[position] != null){
    Drawable c = Drawable.createFromPath(basePath+foto[position]);   // line 56 
    if(c!=null)
        imageView.setImageDrawable(c);
    else
        imageView.setImageResource(R.drawable.default);
    }else{
        imageView.setImageResource(R.drawable.default);                
    }
    return rowView;
}

All seems to work fine, but when I come in and go out to the List for many times(changing Activity) sometimes I obtain the following error:

08-06 15:06:14.110: E/dalvikvm-heap(3527): Out of memory on a 2380816-byte allocation.
08-06 15:06:14.110: W/dalvikvm(3527): threadid=1: thread exiting with uncaught exception (group=0x40a3d1f8)
08-06 15:06:14.120: E/AndroidRuntime(3527): FATAL EXCEPTION: main
08-06 15:06:14.120: E/AndroidRuntime(3527): java.lang.OutOfMemoryError
08-06 15:06:14.120: E/AndroidRuntime(3527):     at android.graphics.BitmapFactory.nativeDecodeStream(Native Method)
08-06 15:06:14.120: E/AndroidRuntime(3527):     at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:493)
08-06 15:06:14.120: E/AndroidRuntime(3527):     at android.graphics.BitmapFactory.decodeFile(BitmapFactory.java:299)
08-06 15:06:14.120: E/AndroidRuntime(3527):     at android.graphics.BitmapFactory.decodeFile(BitmapFactory.java:324)
08-06 15:06:14.120: E/AndroidRuntime(3527):     at android.graphics.drawable.Drawable.createFromPath(Drawable.java:880)
08-06 15:06:14.120: E/AndroidRuntime(3527):     at host.framework.component.MySimpleArrayAdapter.getView(MySimpleArrayAdapter.java:56)
08-06 15:06:14.120: E/AndroidRuntime(3527):     at android.widget.AbsListView.obtainView(AbsListView.java:2012)
08-06 15:06:14.120: E/AndroidRuntime(3527):     at android.widget.ListView.makeAndAddView(ListView.java:1772)
08-06 15:06:14.120: E/AndroidRuntime(3527):     at android.widget.ListView.fillUp(ListView.java:705)
08-06 15:06:14.120: E/AndroidRuntime(3527):     at android.widget.ListView.fillGap(ListView.java:645)
08-06 15:06:14.120: E/AndroidRuntime(3527):     at android.widget.AbsListView.trackMotionScroll(AbsListView.java:4546)
08-06 15:06:14.120: E/AndroidRuntime(3527):     at android.widget.AbsListView$FlingRunnable.run(AbsListView.java:3813)
08-06 15:06:14.120: E/AndroidRuntime(3527):     at android.os.Handler.handleCallback(Handler.java:605)
08-06 15:06:14.120: E/AndroidRuntime(3527):     at android.os.Handler.dispatchMessage(Handler.java:92)
08-06 15:06:14.120: E/AndroidRuntime(3527):     at android.os.Looper.loop(Looper.java:137)
08-06 15:06:14.120: E/AndroidRuntime(3527):     at android.app.ActivityThread.main(ActivityThread.java:4424)
08-06 15:06:14.120: E/AndroidRuntime(3527):     at java.lang.reflect.Method.invokeNative(Native Method)
08-06 15:06:14.120: E/AndroidRuntime(3527):     at java.lang.reflect.Method.invoke(Method.java:511)
08-06 15:06:14.120: E/AndroidRuntime(3527):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
08-06 15:06:14.120: E/AndroidRuntime(3527):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
08-06 15:06:14.120: E/AndroidRuntime(3527):     at dalvik.system.NativeStart.main(Native Method)
08-06 15:06:14.120: W/ActivityManager(149):   Force finishing activity host.activity/.ACT_CircoliDiSupporto
08-06 15:06:14.640: W/ActivityManager(149): Activity pause timeout for ActivityRecord{413de508 host.activity/.ACT_CircoliDiSupporto}
08-06 15:06:24.140: W/ActivityManager(149): Launch timeout has expired, giving up wake lock!
08-06 15:06:24.650: W/ActivityManager(149): Activity idle timeout for ActivityRecord{41389d58 host.activity/.HostActivity}

The line 56 (highlighted in the code) seems to generate the error

Drawable c = Drawable.createFromPath(basePath+foto[position]);
4

2 回答 2

3

当前的实现存在许多问题：

  1. 代码在主/UI 线程 ( ) 上访问并构建位图Drawable c = Drawable.createFromPath(basePath+foto[position]); // line 56，这会使您的列表滚动非常不稳定
  2. 每次请求视图时都会创建一个新的可绘制对象，在 2.x Android 系统上，垃圾收集器 (GC) 收集未引用的位图需要一段时间，从而加剧内存问题
  3. 您从存储中加载图像而不将其缩放到适当的大小，这可能是也可能不是问题，因为我不知道您正在显示的图像的尺寸，也不知道图像的尺寸

我建议您使用通用图像加载器库（https://github.com/nostra13/Android-Universal-Image-Loader），它可以解决上述所有问题。虽然我不确定它是否提供本机本地图像加载功能，或者您是否必须扩展某些类才能拥有这种能力。

[编辑]

我不建议推出你自己的解决方案，因为它需要的时间比你最初想象的要多（相信我......）。但是，如果您真的想这样做，可以查看本教程：http ://codehenge.net/blog/2011/06/android-development-tutorial-asynchronous-lazy-loading-and-caching-of-listview-images /

上面的教程解决了 #1 和 #2，对于 #3，请检查：Strange out of memory issue while loading an image to a Bitmap object

于 2013-08-06T14:24:57.923 回答
1

首先，您需要一个像LruCache这样的数据结构来保存正在创建的可绘制对象。

如何确保我的对象被正确释放？

在使用数据结构破坏活动时，确保将类的对象设为空或清除它的内部对象。（这将告诉 gc 该对象已准备好被清除（在大多数情况下））。

在主线程上运行文件操作也不是最好的方法，因为它会在列表视图滚动中引入抖动。尝试在辅助线程中执行此操作。

于 2013-08-06T14:15:02.080 回答