android - 使用 viewpager + imageview 时出现内存不足错误，即使使用缓存内存和异步任务也是如此

Question

请问以前有人在 viewpager 中添加过很多 ImageView 吗？我有一个调用 fragment 类的 Activity 来将包含图像的 fragment 创建到 viewpager 中，并且这个 fragment 类包含缓存图像的方法，如果它不存在于缓存内存中并调整图像大小并让可绘制对象在异步任务中执行减少前台任务的时间消耗......但是用所有这些方法来消除内存不足错误我仍然有这个错误!!!已经两三天尝试不同的方法，但没有一个奏效...所以请有任何想法!!

我的代码是:

import java.lang.ref.WeakReference;

import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.drawable.BitmapDrawable;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.util.LruCache;
import android.util.DisplayMetrics;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;


public class ScreenSlidePageFragment extends Fragment {
    /**
     * The argument key for the page number this fragment represents.
     */
    public static final String ARG_PAGE = "page";
    private LruCache<String, Bitmap> mMemoryCache;

    /**
     * The fragment's page number, which is set to the argument value for {@link #ARG_PAGE}.
     */
    ImageView img;
    int height;
    int width;
    private int mPageNumber;
    private int[] pics = {R.drawable.intro1, R.drawable.intro2,R.drawable.intro3,R.drawable.intro4,R.drawable.intro5,R.drawable.intro6,R.drawable.intro7,R.drawable.intro8,
            R.drawable.intro9,R.drawable.intro10,R.drawable.intro11,R.drawable.intro12,R.drawable.intro13,R.drawable.intro14,R.drawable.intro15,R.drawable.intro16,R.drawable.intro17,R.drawable.intro18,
            R.drawable.intro19,R.drawable.intro20,R.drawable.intro21,R.drawable.intro22,R.drawable.intro23,R.drawable.intro24,R.drawable.intro25,R.drawable.intro26,R.drawable.intro27,R.drawable.intro28,R.drawable.intro29,R.drawable.intro30,
            R.drawable.intro31,R.drawable.intro32,R.drawable.intro33,R.drawable.intro34,R.drawable.intro35,R.drawable.intro36,R.drawable.intro37,R.drawable.intro38,R.drawable.intro39,R.drawable.intro40,R.drawable.intro41,R.drawable.intro42,
            R.drawable.intro43,R.drawable.intro44,R.drawable.intro45,R.drawable.intro46,R.drawable.intro47,R.drawable.intro48,R.drawable.intro49,R.drawable.intro50,R.drawable.intro51,R.drawable.intro52,R.drawable.intro53,R.drawable.intro54,
            R.drawable.intro55,R.drawable.intro56,R.drawable.intro57,R.drawable.intro58,R.drawable.intro59,R.drawable.intro60,R.drawable.intro61,R.drawable.intro62,R.drawable.intro63,R.drawable.intro64,R.drawable.intro65,R.drawable.intro66,
            R.drawable.intro67,R.drawable.intro68,R.drawable.intro69,R.drawable.intro70,R.drawable.intro71,R.drawable.intro72,R.drawable.intro73};
    int count=72;//it's the number of the images-1;


    /**
     * Factory method for this fragment class. Constructs a new fragment for the given page number.
     */
    public static ScreenSlidePageFragment create(int pageNumber) {
        ScreenSlidePageFragment fragment = new ScreenSlidePageFragment();
        Bundle args = new Bundle();
        args.putInt(ARG_PAGE, pageNumber);
        fragment.setArguments(args);
        return fragment;
    }

    public ScreenSlidePageFragment() {
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
     // Get max available VM memory, exceeding this amount will throw an
        // OutOfMemory exception. Stored in kilobytes as LruCache takes an
        // int in its constructor.
        DisplayMetrics displaymetrics = new DisplayMetrics();
        getActivity().getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
        height = displaymetrics.heightPixels;
        width = displaymetrics.widthPixels;
        final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);

        // Use 1/8th of the available memory for this memory cache.
        final int cacheSize = maxMemory / 8;

        mMemoryCache = new LruCache<String, Bitmap>(cacheSize) {
            @Override
            protected int sizeOf(String key, Bitmap bitmap) {
                // The cache size will be measured in kilobytes rather than
                // number of items.
                return bitmap.getRowBytes()*bitmap.getHeight() / 1024;
            }
        };

        mPageNumber = getArguments().getInt(ARG_PAGE);
    }

    public void addBitmapToMemoryCache(String key, Bitmap bitmap) {
        if (getBitmapFromMemCache(key) == null) {
            mMemoryCache.put(key, bitmap);
        }
    }

    public Bitmap getBitmapFromMemCache(String key) {
        return mMemoryCache.get(key);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {       
    ViewGroup rootView = (ViewGroup) inflater.inflate(R.layout.image_view_layout, container, false);
    img=(ImageView) rootView.findViewById(R.id.img_pager);
    final String imageKey = String.valueOf(pics[count-mPageNumber]);
    final Bitmap bitmap = getBitmapFromMemCache(imageKey);
            if (bitmap != null) {
                    img.setImageBitmap(bitmap);
                } else {
                    img.setImageResource(pics[count-mPageNumber]);
                    BitmapWorkerTask task = new BitmapWorkerTask(img);
                    task.execute(pics[count-mPageNumber]);
                }
        return rootView;
    }




    @Override
    public void onDetach(){
         super.onDetach();
         super.onDetach();
        Bitmap bitmap = ((BitmapDrawable)img.getDrawable()).getBitmap();
        bitmap.recycle();       
        //FragmentManager fragmentManager = getFragmentManager();
        //FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        //fragmentTransaction.remove(this).commit();
    }


    /**
     * Returns the page number represented by this fragment object.
     */
    public int getPageNumber() {
        return mPageNumber;
    }

    class BitmapWorkerTask extends AsyncTask<Integer, Void, Bitmap> {
        private final WeakReference<ImageView> imageViewReference;

        public BitmapWorkerTask(ImageView imageView) {
            // Use a WeakReference to ensure the ImageView can be garbage collected
            imageViewReference = new WeakReference<ImageView>(imageView);
        }

        // Decode image in background.
        @Override
        protected Bitmap doInBackground(Integer... params) {
            final Bitmap bitmap = decodeSampledBitmapFromResource(getResources(), params[0],width,height);
            addBitmapToMemoryCache(String.valueOf(params[0]), bitmap);
            return bitmap;
        }

        // Once complete, see if ImageView is still around and set bitmap.
        @Override
        protected void onPostExecute(Bitmap bitmap) {
            if (imageViewReference != null && bitmap != null) {
                final ImageView imageView = imageViewReference.get();
                if (imageView != null) {
                    imageView.setImageBitmap(bitmap);
                }
            }
        }
    }

    public static Bitmap decodeSampledBitmapFromResource(Resources res, int resId,
            int reqWidth, int reqHeight) {

        // First decode with inJustDecodeBounds=true to check dimensions
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeResource(res, resId, options);

        // Calculate inSampleSize
        options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);

        // Decode bitmap with inSampleSize set
        options.inJustDecodeBounds = false;
        return BitmapFactory.decodeResource(res, resId, options);
    }


    public static int calculateInSampleSize(
            BitmapFactory.Options options, int reqWidth, int reqHeight) {
    // Raw height and width of image
    final int height = options.outHeight;
    final int width = options.outWidth;
    int inSampleSize = 1;

    if (height > reqHeight || width > reqWidth) {

        // Calculate ratios of height and width to requested height and width
        final int heightRatio = Math.round((float) height / (float) reqHeight);
        final int widthRatio = Math.round((float) width / (float) reqWidth);

        // Choose the smallest ratio as inSampleSize value, this will guarantee
        // a final image with both dimensions larger than or equal to the
        // requested height and width.
        inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
    }

    return inSampleSize;
}

}

Activity 是:

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.Menu;



public class Introduction_Activity extends FragmentActivity {
     private static final int NUM_PAGES = 73;

    private ViewPager mPager;

    /**
     * The pager adapter, which provides the pages to the view pager widget.
     */
    private PagerAdapter mPagerAdapter;

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


        // Instantiate a ViewPager and a PagerAdapter.
        mPager = (ViewPager) findViewById(R.id.imgs_viewpager);
        mPagerAdapter = new ScreenSlidePagerAdapter(getSupportFragmentManager());
        mPager.setAdapter(mPagerAdapter);
        mPager.setCurrentItem(NUM_PAGES-1,false);    
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.introduction_, menu);
        return true;
    }



    private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
        public ScreenSlidePagerAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int position) {

            return ScreenSlidePageFragment.create(position);

            }

        @Override
        public int getCount() {
            return NUM_PAGES;
        }


    }


}

问题:

10-02 06:21:48.230: E/dalvikvm-heap(8944): Out of memory on a 7071376-byte allocation.
10-02 06:21:48.245: E/AndroidRuntime(8944): FATAL EXCEPTION: AsyncTask #4
10-02 06:21:48.245: E/AndroidRuntime(8944): java.lang.RuntimeException: An error occured while executing doInBackground()
10-02 06:21:48.245: E/AndroidRuntime(8944):     at android.os.AsyncTask$3.done(AsyncTask.java:278)
10-02 06:21:48.245: E/AndroidRuntime(8944):     at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
10-02 06:21:48.245: E/AndroidRuntime(8944):     at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
10-02 06:21:48.245: E/AndroidRuntime(8944):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
10-02 06:21:48.245: E/AndroidRuntime(8944):     at java.util.concurrent.FutureTask.run(FutureTask.java:137)
10-02 06:21:48.245: E/AndroidRuntime(8944):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
10-02 06:21:48.245: E/AndroidRuntime(8944):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
10-02 06:21:48.245: E/AndroidRuntime(8944):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
10-02 06:21:48.245: E/AndroidRuntime(8944):     at java.lang.Thread.run(Thread.java:856)
10-02 06:21:48.245: E/AndroidRuntime(8944): Caused by: java.lang.OutOfMemoryError
10-02 06:21:48.245: E/AndroidRuntime(8944):     at android.graphics.Bitmap.nativeCreate(Native Method)
10-02 06:21:48.245: E/AndroidRuntime(8944):     at android.graphics.Bitmap.createBitmap(Bitmap.java:605)
10-02 06:21:48.245: E/AndroidRuntime(8944):     at android.graphics.Bitmap.createBitmap(Bitmap.java:551)
10-02 06:21:48.245: E/AndroidRuntime(8944):     at android.graphics.Bitmap.createScaledBitmap(Bitmap.java:437)
10-02 06:21:48.245: E/AndroidRuntime(8944):     at android.graphics.BitmapFactory.finishDecode(BitmapFactory.java:618)
10-02 06:21:48.245: E/AndroidRuntime(8944):     at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:593)
10-02 06:21:48.245: E/AndroidRuntime(8944):     at android.graphics.BitmapFactory.decodeResourceStream(BitmapFactory.java:445)
10-02 06:21:48.245: E/AndroidRuntime(8944):     at android.graphics.BitmapFactory.decodeResource(BitmapFactory.java:468)
10-02 06:21:48.245: E/AndroidRuntime(8944):     at packagename.ScreenSlidePageFragment.decodeSampledBitmapFromResource(ScreenSlidePageFragment.java:178)
10-02 06:21:48.245: E/AndroidRuntime(8944):     at packagename.ScreenSlidePageFragment$BitmapWorkerTask.doInBackground(ScreenSlidePageFragment.java:148)
10-02 06:21:48.245: E/AndroidRuntime(8944):     at packagename.ScreenSlidePageFragment$BitmapWorkerTask.doInBackground(ScreenSlidePageFragment.java:1)
10-02 06:21:48.245: E/AndroidRuntime(8944):     at android.os.AsyncTask$2.call(AsyncTask.java:264)
10-02 06:21:48.245: E/AndroidRuntime(8944):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
10-02 06:21:48.245: E/AndroidRuntime(8944):     ... 5 more

Answer 1

试试这个

将以下内容添加到 list 中的应用程序标签中

android:largeHeap="true"

希望对你有所帮助。