java - 内存不足异常+分析hprof文件转储

Question

这与这个问题有关:

java.lang.OutOfMemoryError at android.graphics.BitmapFactory.nativeDecodeAsset(Native Method)

我创建了有问题的转储文件，它提供了以下信息:

One instance of "byte[]" loaded by "<system class loader>" occupies 1,10,59,216
(51.02%) bytes. The memory is accumulated in one instance of "byte[]" 
 loaded by "<system class loader>".

Keywords byte[]

那么现在可以做什么呢？如何清除问题？

我的 list_objects[context]-入站文件:

CLASS NAME                                                                 SHALLOW HEAP   RETAINED HEAP  
byte[11059200] @ 0xb4979590                                               |  1,10,59,216 |   1,10,59,216
mBuffer android.graphics.Bitmap @ 0xb3dc68d8                              |48            | 48
mBitmap android.graphics.drawable.BitmapDrawable @ 0xb3dbba60             | 72           | 144
mBackground android.widget.RelativeLayout @ 0xb3db3fc0                    |512           | 10,144
mBitmap android.graphics.drawable.BitmapDrawable$BitmapState @ 0xb3dc0068 |40          | 40
mBitmapState android.graphics.drawable.BitmapDrawable @ 0xb3dbba60        |72          |  144
referent java.lang.ref.WeakReference @ 0xb3dc2d68                         |24          |  24

如何解决内存问题？

我的home_screen.java

 protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.home_page);
    main();
 private void main() {
    // TODO Auto-generated method stub
    
    
    final Button home;
    final Button aboutus;
    final Button contacts;
    final Button clients;
    final Button services;
    
    try
    {

    home = (Button)findViewById(R.id.btnHome);
    aboutus = (Button)findViewById(R.id.btnAboutus);
    clients = (Button)findViewById(R.id.btnClients);
    contacts = (Button)findViewById(R.id.btnContacts);
    services = (Button)findViewById(R.id.btnServices);
    
    home.setOnClickListener(new OnClickListener() {
        
        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            Bitmap b = BitmapFactory.decodeResource(getResources(),R.drawable.home1);
            Drawable d = new BitmapDrawable(getResources(),b);              
            home.setBackgroundDrawable(d);
            System.gc();
            Intent myIntent = new Intent(Home_Screen.this, Button_Anime.class);
            startActivity(myIntent);
        }
    });
    aboutus.setOnClickListener(new OnClickListener() {
        
        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            Bitmap b = BitmapFactory.decodeResource(getResources(),R.drawable.about1 );
            Drawable d = new BitmapDrawable(getResources(),b); 
            aboutus.setBackgroundDrawable(d);
            Intent myIntent = new Intent(Home_Screen.this, AboutUs.class);
            startActivity(myIntent);
        }
    });
    clients.setOnClickListener(new  OnClickListener() {
        
        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            
            Bitmap b = BitmapFactory.decodeResource(getResources(),R.drawable.clients1 );
            Drawable d = new BitmapDrawable(getResources(),b); 
            clients.setBackgroundDrawable(d);
            Intent myIntent = new Intent(Home_Screen.this, Clients.class);
            startActivity(myIntent);
        }
    });
    contacts.setOnClickListener(new OnClickListener() {
        
        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            
            Bitmap b = BitmapFactory.decodeResource(getResources(),R.drawable.contact1);
            Drawable d = new BitmapDrawable(getResources(),b);
            contacts.setBackgroundDrawable(d);
            Intent myIntent = new Intent(Home_Screen.this, Contacts.class);
            startActivity(myIntent);
        }
    });
    services.setOnClickListener(new OnClickListener() {
        
        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            
            Bitmap b = BitmapFactory.decodeResource(getResources(),R.drawable.services1 );
            Drawable d = new BitmapDrawable(getResources(),b);
            services.setBackgroundDrawable(d);
            Intent myIntent = new Intent(Home_Screen.this, Services.class);
            startActivity(myIntent);
        }
    });

    }
    catch(Exception e)
    {
        e.printStackTrace();
    }
}

Answer 1

想法是对图像进行降采样，使其在较小的屏幕上看起来不错，并且您不必将整个位图加载到内存中。

1) 首先获取您将在其上显示的 ImageView/屏幕的大小。

2) 通过传入BitmapFactory.Options.inJustDecodeBounds 读取您的位图大小。这将为您提供位图的大小，而不是加载整个位图。

3) 获取样本量。计算屏幕的高和宽与图像高和宽的比值。使用最小的尺寸，这样最大的尺寸看起来也不错。

4) 最后使用下面的函数得到不会占用你内存的下采样图像。

2)(代码)

BitmapFactory.Options bitmapOptions = new BitmapFactory.Options();
bitmapOptions.inJustDecodeBounds = true;
BitmapFactory.decodeStream(inputStream, null, bitmapOptions);
int imageWidth = bitmapOptions.outWidth;
int imageHeight = bitmapOptions.outHeight;
inputStream.close();

4)(代码)

private Bitmap downscaleBitmapUsingDensities(final int sampleSize,final int imageResId)
  {
  final Options bitmapOptions=new Options();
  bitmapOptions.inDensity=sampleSize;
  bitmapOptions.inTargetDensity=1;
  final Bitmap scaledBitmap=BitmapFactory.decodeResource(getResources(),imageResId,bitmapOptions);
  scaledBitmap.setDensity(Bitmap.DENSITY_NONE);
  return scaledBitmap;
  }