android 如何避免出现 memory 错误

Question

我有很多图像说 500ish 分布在 20 个左右的片段中，图像都非常小并且加载都很好，但是我让用户可以选择 3 种不同的图像，现在如果用户更改图像我出现 OOM 错误，所以我认为这是我处理图像的方式，我认为我需要先回收旧图像，但我对如何做到这一点没有信心，有人能帮忙吗？

这是我如何填充我的适配器我刚刚添加了两个项目来简化事情

    private void prepareCardData(){

    CardWriter cardWriter = new CardWriter(getResources().getDrawable(R.drawable.dog),"DOG","dog ");
    cardMakerList.add(cardWriter);

    cardWriter = new CardWriter(getResources().getDrawable(R.drawable.cat_ic),"CAT","cat ");
    cardMakerList.add(cardWriter);

    cardAdapter.notifyDataSetChanged();
}

这就是我实际上只是等待共享偏好更改并调用方法的地方

private SharedPreferences.OnSharedPreferenceChangeListener listener = new     
SharedPreferences.OnSharedPreferenceChangeListener() {
    @Override
    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
        if(key.equals("ICONS SELECTED")){
            cardsChoice.setIcons(getActivity());
            cardsToSet();
            System.out.println("OneFrag pref listener");
        }
    }
};
public void cardsToSet(){
    if (cardsChoice.bool_fragTwo == false) {
        if (cardsChoice.group == 1) {
            cardMakerList.clear();
            prepareCardData();
            cardsChoice.bool_fragTwo = true;
        }
        if (cardsChoice.group == 2) {
            cardMakerList.clear();
            prepareSimpleCardData();
            cardsChoice.bool_fragTwo = true;
        }
        if (cardsChoice.group == 3) {
            cardMakerList.clear();
            preparePhotoCardData();
            cardsChoice.bool_fragTwo = true;
        }
    }
}

如前所述，我认为我需要在自己的线程中运行它并清理和不再需要的图像，但我认为还有更多其他人可以提供帮助？

这是堆栈跟踪

06-12 17:39:47.878 13189-13219/ss.sealstudios.com.socialstories E/Surface: getSlotFromBufferLocked: unknown buffer: 0x8a12fe70
06-12 17:39:47.985 13189-13189/ss.sealstudios.com.socialstories I/System.out: OneFrag pref listener
06-12 17:39:47.987 13189-13189/ss.sealstudios.com.socialstories I/System.out: OneFrag pref listener
06-12 17:39:48.233 13189-13199/ss.sealstudios.com.socialstories I/art: Clamp target GC heap from 265MB to 256MB
06-12 17:39:48.380 13189-13189/ss.sealstudios.com.socialstories I/System.out: OneFrag pref listener
06-12 17:39:48.410 13189-13189/ss.sealstudios.com.socialstories I/art: Starting a blocking GC Alloc
06-12 17:39:48.410 13189-13189/ss.sealstudios.com.socialstories I/art: Starting a blocking GC Alloc
06-12 17:39:48.416 13189-13189/ss.sealstudios.com.socialstories I/art: Alloc sticky concurrent mark sweep GC freed 108(4KB) AllocSpace objects, 0(0B) LOS objects, 0% free, 254MB/256MB, paused 303us total 5.710ms
06-12 17:39:48.417 13189-13189/ss.sealstudios.com.socialstories I/art: Starting a blocking GC Alloc
06-12 17:39:48.433 13189-13189/ss.sealstudios.com.socialstories I/art: Clamp target GC heap from 283MB to 256MB
06-12 17:39:48.433 13189-13189/ss.sealstudios.com.socialstories I/art: Alloc partial concurrent mark sweep GC freed 5841(393KB) AllocSpace objects, 2(3MB) LOS objects, 1% free, 251MB/256MB, paused 793us total 15.361ms
06-12 17:39:48.493 13189-13189/ss.sealstudios.com.socialstories I/art: Starting a blocking GC Alloc
06-12 17:39:48.494 13189-13189/ss.sealstudios.com.socialstories I/art: Starting a blocking GC Alloc
06-12 17:39:48.502 13189-13189/ss.sealstudios.com.socialstories I/art: Alloc sticky concurrent mark sweep GC freed 17(688B) AllocSpace objects, 0(0B) LOS objects, 0% free, 255MB/256MB, paused 545us total 7.748ms
06-12 17:39:48.503 13189-13189/ss.sealstudios.com.socialstories I/art: Starting a blocking GC Alloc
06-12 17:39:48.526 13189-13189/ss.sealstudios.com.socialstories I/art: Clamp target GC heap from 287MB to 256MB
06-12 17:39:48.526 13189-13189/ss.sealstudios.com.socialstories I/art: Alloc partial concurrent mark sweep GC freed 23(944B) AllocSpace objects, 0(0B) LOS objects, 0% free, 255MB/256MB, paused 494us total 22.482ms
06-12 17:39:48.527 13189-13189/ss.sealstudios.com.socialstories I/art: Starting a blocking GC Alloc
06-12 17:39:48.567 13189-13189/ss.sealstudios.com.socialstories I/art: Clamp target GC heap from 287MB to 256MB
06-12 17:39:48.567 13189-13189/ss.sealstudios.com.socialstories I/art: Alloc concurrent mark sweep GC freed 9(12KB) AllocSpace objects, 0(0B) LOS objects, 0% free, 255MB/256MB, paused 499us total 38.887ms
06-12 17:39:48.568 13189-13189/ss.sealstudios.com.socialstories I/art: Forcing collection of SoftReferences for 2025KB allocation
06-12 17:39:48.568 13189-13189/ss.sealstudios.com.socialstories I/art: Starting a blocking GC Alloc
06-12 17:39:48.597 13189-13189/ss.sealstudios.com.socialstories I/art: Clamp target GC heap from 287MB to 256MB
06-12 17:39:48.597 13189-13189/ss.sealstudios.com.socialstories I/art: Alloc concurrent mark sweep GC freed 11(344B) AllocSpace objects, 0(0B) LOS objects, 0% free, 255MB/256MB, paused 501us total 28.481ms
06-12 17:39:48.601 13189-13189/ss.sealstudios.com.socialstories W/art: Throwing OutOfMemoryError "Failed to allocate a 2073612 byte allocation with 559872 free bytes and 546KB until OOM"
06-12 17:39:48.603 13189-13189/ss.sealstudios.com.socialstories I/art: Starting a blocking GC Alloc
06-12 17:39:48.603 13189-13189/ss.sealstudios.com.socialstories I/art: Starting a blocking GC Alloc
06-12 17:39:48.610 13189-13189/ss.sealstudios.com.socialstories I/art: Alloc sticky concurrent mark sweep GC freed 3(448B) AllocSpace objects, 0(0B) LOS objects, 0% free, 255MB/256MB, paused 484us total 6.214ms
06-12 17:39:48.611 13189-13189/ss.sealstudios.com.socialstories I/art: Starting a blocking GC Alloc
06-12 17:39:48.643 13189-13189/ss.sealstudios.com.socialstories I/art: Clamp target GC heap from 287MB to 256MB
06-12 17:39:48.643 13189-13189/ss.sealstudios.com.socialstories I/art: Alloc partial concurrent mark sweep GC freed 6(192B) AllocSpace objects, 0(0B) LOS objects, 0% free, 255MB/256MB, paused 1.131ms total 31.104ms
06-12 17:39:48.644 13189-13189/ss.sealstudios.com.socialstories I/art: Starting a blocking GC Alloc
06-12 17:39:48.673 13189-13189/ss.sealstudios.com.socialstories I/art: Clamp target GC heap from 287MB to 256MB
06-12 17:39:48.673 13189-13189/ss.sealstudios.com.socialstories I/art: Alloc concurrent mark sweep GC freed 3(96B) AllocSpace objects, 0(0B) LOS objects, 0% free, 255MB/256MB, paused 631us total 29.306ms
06-12 17:39:48.674 13189-13189/ss.sealstudios.com.socialstories I/art: Forcing collection of SoftReferences for 2025KB allocation
06-12 17:39:48.674 13189-13189/ss.sealstudios.com.socialstories I/art: Starting a blocking GC Alloc
06-12 17:39:48.704 13189-13189/ss.sealstudios.com.socialstories I/art: Clamp target GC heap from 287MB to 256MB
06-12 17:39:48.704 13189-13189/ss.sealstudios.com.socialstories I/art: Alloc concurrent mark sweep GC freed 3(96B) AllocSpace objects, 0(0B) LOS objects, 0% free, 255MB/256MB, paused 306us total 29.616ms
06-12 17:39:48.705 13189-13189/ss.sealstudios.com.socialstories W/art: Throwing OutOfMemoryError "Failed to allocate a 2073612 byte allocation with 559872 free bytes and 546KB until OOM"
06-12 17:39:48.709 13189-13189/ss.sealstudios.com.socialstories D/skia: --- allocation failed for scaled bitmap
06-12 17:39:48.709 13189-13189/ss.sealstudios.com.socialstories D/AndroidRuntime: Shutting down VM
06-12 17:39:48.724 13189-13189/ss.sealstudios.com.socialstories E/AndroidRuntime: FATAL EXCEPTION: main
                                                                                  Process: ss.sealstudios.com.socialstories, PID: 13189
                                                                                  java.lang.OutOfMemoryError: Failed to allocate a 2073612 byte allocation with 559872 free bytes and 546KB until OOM
                                                                                      at dalvik.system.VMRuntime.newNonMovableArray(Native Method)
                                                                                      at android.graphics.BitmapFactory.nativeDecodeAsset(Native Method)
                                                                                      at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:609)
                                                                                      at android.graphics.BitmapFactory.decodeResourceStream(BitmapFactory.java:444)
                                                                                      at android.graphics.drawable.Drawable.createFromResourceStream(Drawable.java:1080)
                                                                                      at android.content.res.Resources.loadDrawableForCookie(Resources.java:2738)
                                                                                      at android.content.res.Resources.loadDrawable(Resources.java:2643)
                                                                                      at android.content.res.Resources.getDrawable(Resources.java:833)
                                                                                      at android.content.res.Resources.getDrawable(Resources.java:786)
                                                                                      at ss.sealstudios.com.socialstories.TwoFragment.prepareCardData(TwoFragment.java:280)
                                                                                      at ss.sealstudios.com.socialstories.TwoFragment.cardsToSet(TwoFragment.java:245)
                                                                                      at ss.sealstudios.com.socialstories.TwoFragment$2.onSharedPreferenceChanged(TwoFragment.java:236)
                                                                                      at android.app.SharedPreferencesImpl$EditorImpl.notifyListeners(SharedPreferencesImpl.java:479)
                                                                                      at android.app.SharedPreferencesImpl$EditorImpl.apply(SharedPreferencesImpl.java:387)
                                                                                      at android.preference.Preference.tryCommit(Preference.java:1419)
                                                                                      at android.preference.Preference.persistString(Preference.java:1452)
                                                                                      at android.preference.ListPreference.setValue(ListPreference.java:148)
                                                                                      at android.preference.ListPreference.onDialogClosed(ListPreference.java:283)
                                                                                      at android.preference.DialogPreference.onDismiss(DialogPreference.java:395)
                                                                                      at android.app.Dialog$ListenersHandler.handleMessage(Dialog.java:1328)
                                                                                      at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                                      at android.os.Looper.loop(Looper.java:148)
                                                                                      at android.app.ActivityThread.main(ActivityThread.java:5527)
                                                                                      at java.lang.reflect.Method.invoke(Native Method)
                                                                                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:730)
                                                                                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:620)

Answer 1

如果图像视图包含一个可绘制位图的实例

Drawable drawable = imageView.getDrawable();
if(drawable!=null && BitmapDrawable.class.isAssignableFrom(drawable.getClass())) {
    BitmapDrawable bitmapDrawable = (BitmapDrawable) drawable;
    Bitmap bitmap = bitmapDrawable.getBitmap();
    if(bitmap != null && !bitmap.isRecycled()) bitmap.recycle();
}

但...

如果您从不大的可绘制文件夹中加载位图（以兆字节为单位），那么您应该不会真正遇到问题。

如果您加载资产，您需要检查它们是否最适合您显示它们的位置，例如，如果您显示图像的区域大小为 64x64，则将 ImageView 设置为大小为 1024 x 1024 的图像是没有意义的。

OOM 通常是由于加载了未知大小的图像或只是如上所述的图像大小错误，频繁交换 ImageView 通常不会给您带来最佳大小图像的问题。

您应该阅读一些关于位图的指南：

https://developer.android.com/training/displaying-bitmaps/index.html

对于您的情况：

这是堆栈跟踪的基本片段：

FATAL EXCEPTION: main Process: ss.sealstudios.com.socialstories, PID: 13189 
java.lang.OutOfMemoryError: Failed to allocate a 2073612 byte allocation with 559872 free bytes and 546KB until OOM 
at dalvik.system.VMRuntime.newNonMovableArray(Native Method) 
at android.graphics.BitmapFactory.nativeDecodeAsset(Native Method) at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:609) 
at android.graphics.BitmapFactory.decodeResourceStream(BitmapFactory.java:444) 
at android.graphics.drawable.Drawable.createFromResourceStream(Drawable.java:1080) 
at android.content.res.Resources.loadDrawableForCookie(Resources.java:2738) 
at android.content.res.Resources.loadDrawable(Resources.java:2643) 
at android.content.res.Resources.getDrawable(Resources.java:833) at android.content.res.Resources.getDrawable(Resources.java:786) 
at ss.sealstudios.com.socialstories.TwoFragment.prepareCardData(TwoFragment.java:280) 

未能分配 2073612 字节分配，其中 559872 字节和 546KB 直到 OOM

所以一般来说：

• 在方法TwoFragment.prepareCardData(TwoFragment.java:280)之前调用Resources.getDrawable(..)你应该得到图像视图和回收位图..
• 在片段/活动中，您还应该在 onDestroy() 方法中回收位图

没有更多代码，我无法确定例如某些循环是否导致 OOM 或者您没有释放资源......

您也可以在将资源设置为图像视图之前执行此操作（缩放图像）：

内存不足错误 ImageView 问题

警告！！！

不要使用您已经回收的图像。

你会得到例外：画布：尝试使用回收的位图

android >2.3.3 并不严格要求bitmap.recycle() 。 如果您仍想强制回收此内存，则必须找到一种方法来检查何时确实不再需要该位图（即，Canvas 有机会完成其绘图操作）。

问题是您可能广泛使用位图（分配速度可能大于位图被回收的速度），那么您可能希望尽快回收未使用的位图。使用完位图后，您应该调用 recycle()。

永远记住不要在屏幕上显示位图时尝试回收它。

所以：

• 获取对旧位图的引用
• 设置新的
• 无效视图
• 检查旧位图是否尚未回收
• 回收旧的
• 你也可以调用 System.gc(); ^

^向虚拟机表明现在是运行垃圾收集器的好时机。 请注意，这只是一个提示。 不能保证垃圾收集器会真正运行。

调用ImageView.setImageBitmap(); 或相似性不会回收位图使用的内存...

为什么？ 因为当您特别查看 ImageView 方法的 impl 时：

private void updateDrawable(Drawable d) {
    if (d != mRecycleableBitmapDrawable && mRecycleableBitmapDrawable != null) {
        mRecycleableBitmapDrawable.setBitmap(null);
    }
...


public void setImageResource(@DrawableRes int resId) {
    // The resource configuration may have changed, so we should always
    // try to load the resource even if the resId hasn't changed.
    final int oldWidth = mDrawableWidth;
    final int oldHeight = mDrawableHeight;

    updateDrawable(null);
....

public void setImageBitmap(Bitmap bm) {
    // Hacky fix to force setImageDrawable to do a full setImageDrawable
    // instead of doing an object reference comparison
    mDrawable = null;
    if (mRecycleableBitmapDrawable == null) {
        mRecycleableBitmapDrawable = new ImageViewBitmapDrawable(
                mContext.getResources(), bm);
    } else {
        mRecycleableBitmapDrawable.setBitmap(bm);
    }
    setImageDrawable(mRecycleableBitmapDrawable);
}

也可以看看：

https://developer.android.com/training/displaying-bitmaps/manage-memory.html

Answer 2

项目中的线程完成后，调用 System.gc(); 方法。