android - 调整一个ImageView的大小后，出现无尽的GC_FOR_ALLOC

我在日志猫中得到了无尽的GC_FOR_ALLOC，如下所示：

32ms, total 32ms
07-01 12:23:28.946  14905-14905/com.dodosocial.lowongan D/dalvikvm﹕ GC_FOR_ALLOC freed 1994K, 32% free 18349K/26896K, paused 15ms, total 15ms
07-01 12:23:29.116  14905-14905/com.dodosocial.lowongan D/dalvikvm﹕ GC_FOR_ALLOC freed 3006K, 32% free 18381K/26896K, paused 20ms, total 20ms
07-01 12:23:29.376  14905-14905/com.dodosocial.lowongan D/dalvikvm﹕ GC_FOR_ALLOC freed 4671K, 33% free 18284K/26896K, paused 17ms, total 17ms
07-01 12:23:29.496  14905-14905/com.dodosocial.lowongan D/dalvikvm﹕ GC_FOR_ALLOC freed 1898K, 32% free 18379K/26896K, paused 18ms, total 18ms
07-01 12:23:29.606  14905-14905/com.dodosocial.lowongan D/dalvikvm﹕ GC_FOR_ALLOC freed 1994K, 32% free 18349K/26896K, paused 17ms, total 17ms
07-01 12:23:29.806  14905-14905/com.dodosocial.lowongan D/dalvikvm﹕ GC_FOR_ALLOC freed 3006K, 32% free 18381K/26896K, paused 15ms, total 16ms
07-01 12:23:30.086  14905-14905/com.dodosocial.lowongan D/dalvikvm﹕ GC_FOR_ALLOC freed 4671K, 33% free 18283K/26896K, paused 17ms, total 19ms
07-01 12:23:30.206  14905-14905/com.dodosocial.lowongan D/dalvikvm﹕ GC_FOR_ALLOC freed 2035K, 33% free 18242K/26896K, paused 14ms, total 15ms
07-01 12:23:30.316  14905-14905/com.dodosocial.lowongan D/dalvikvm﹕ GC_FOR_ALLOC freed 1994K, 33% free 18212K/26896K, paused 11ms, total 12ms
07-01 12:23:30.486  14905-14905/com.dodosocial.lowongan D/dalvikvm﹕ GC_FOR_ALLOC freed 3007K, 33% free 18245K/26896K, paused 17ms, total 17ms
07-01 12:23:30.736  14905-14905/com.dodosocial.lowongan D/dalvikvm﹕ GC_FOR_ALLOC freed 4359K, 33% free 18146K/26896K, paused 17ms, total 18ms
07-01 12:23:30.856  14905-14905/com.dodosocial.lowongan D/dalvikvm﹕ GC_FOR_ALLOC freed 1898K, 33% free 18242K/26896K, paused 16ms, total 17ms
07-01 12:23:30.966  14905-14905/com.dodosocial.lowongan D/dalvikvm﹕ GC_FOR_ALLOC freed 1994K, 33% free 18212K/26896K, paused 15ms, total 15ms
07-01 12:23:31.136  14905-14905/com.dodosocial.lowongan D/dalvikvm﹕ GC_FOR_ALLOC freed 3006K, 33% free 18245K/26896K, paused 20ms, total 21ms
07-01 12:23:31.396  14905-14905/com.dodosocial.lowongan D/dalvikvm﹕ GC_FOR_ALLOC freed 4359K, 33% free 18146K/26896K, paused 17ms, total 17ms
07-01 12:23:31.516  14905-14905/com.dodosocial.lowongan D/dalvikvm﹕ GC_FOR_ALLOC freed 1898K, 33% free 18242K/26896K, paused 17ms, total 17ms
07-01 12:23:31.636  14905-14905/com.dodosocial.lowongan D/dalvikvm﹕ GC_FOR_ALLOC freed 1994K, 33% free 18212K/26896K, paused 19ms, total 20ms
07-01 12:23:31.816  14905-14905/com.dodosocial.lowon

找出错误后，我发现这是因为我以编程方式修改了ImageView的高度。
这是我使用的代码：
MyActivity.java

private ImageView mImageUserProfile;
private Bitmap mBitmapIcon;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mImageUserProfile = (ImageView)findViewById(R.id.login_icon);
    mImageUserProfile.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
            mBitmapIcon = CommUtils.getUserProfileBitmap();
            if(mBitmapIcon!=null) {
                setupIcon();
            }
        }
    });
}

private void setupIcon() {
    int bmHeight = mBitmapIcon.getHeight();
    int bmWidth  = mBitmapIcon.getWidth();

    RelativeLayout.LayoutParams layoutParams = (RelativeLayout.LayoutParams)mImageUserProfile.getLayoutParams();
    layoutParams.height = layoutParams.width*bmHeight/bmWidth;
    mImageUserProfile.setLayoutParams(layoutParams);

    mImageUserProfile.setImageBitmap(mBitmapIcon);
}

删除了如下所示的更改高度的代码后，GC_FOR_ALLOC的内容消失了

private void setupIcon() {
  int bmHeight = mBitmapIcon.getHeight();
  int bmWidth  = mBitmapIcon.getWidth();

  /*
  RelativeLayout.LayoutParams layoutParams = (RelativeLayout.LayoutParams)mImageUserProfile.getLayoutParams();
  layoutParams.height = layoutParams.width*bmHeight/bmWidth;
  mImageUserProfile.setLayoutParams(layoutParams);
  */

  mImageUserProfile.setImageBitmap(mBitmapIcon);
}

最佳答案

就像@GabeSechan在对您的问题的评论中所说的那样，由于未删除布局侦听器，导致了无限循环。

通过更改ImageView的高度，可以使它的尺寸无效，从而导致布局不合格。系统将重新布局，然后重新触发GlobalLayoutListener，然后重新触发代码以更改高度...这将导致其他布局...等等。

如果您只记得在更改布局之前删除监听器，则应该没问题。

使用您的代码看起来像这样：

mImageUserProfile
    .getViewTreeObserver()
    .addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
            mBitmapIcon = CommUtils.getUserProfileBitmap();
            if(mBitmapIcon!=null) {
                mImageUserProfile
                    .getViewTreeObserver()
                    .removeGlobalOnLayoutListener(this);

                setupIcon();
            }
        }
    });