Android加载一张3.4MB的图片，不出现OOM

package com.jianda.zuci.showbigphoto;import android.content.res.Resources;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.util.Log;import android.widget.ImageView;public class MainActivity extends AppCompatActivity {    private ImageView iv_bigPhoto;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        iv_bigPhoto = (ImageView)findViewById(R.id.iv_bigPhoto);        int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);//得到系统内存大小        Log.v("maxMemory",maxMemory+"KB");        iv_bigPhoto.setImageBitmap(decodeSampledBitmapFromResource(getResources(),R.drawable.bigphoto,256,144));    }    public static int calculateInSampleSize(BitmapFactory.Options options,int reqWidth,int reqHeight){        final int height = options.outHeight;        final int width = options.outWidth;        int inSampleSize = 1;//If set to a value > 1, requests the decoder to subsample the original image, returning a smaller image to save memory.        if (height > reqHeight || width > reqWidth){            final  int heightRatio = Math.round((float)height / (float)reqHeight);            final  int widthRatio = Math.round((float)width / (float)reqWidth);            inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;            Log.v("inSampleSize",Integer.toString(inSampleSize));        }        return inSampleSize;    }    public static Bitmap decodeSampledBitmapFromResource(Resources res, int resId, int reqWidth, int reqHeight) {        final BitmapFactory.Options options = new BitmapFactory.Options();        options.inJustDecodeBounds = true;//属性设置为true就可以让解析方法禁止为bitmap分配内存，返回值也不再是一个Bitmap对象，而是null        BitmapFactory.decodeResource(res,resId,options);        options.inSampleSize = calculateInSampleSize(options, reqWidth,reqHeight);        Log.v("压缩比",Integer.toString(options.inSampleSize));        options.inJustDecodeBounds = false;        return BitmapFactory.decodeResource(res, resId, options);    }}

运行效果：