Android 内存溢出解决方案（OOM） 整理总结

1 首先将abcSoftRef的referent设置为null，不再引用heap中的new String(abc)对象。2 将heap中的new String(abc)对象设置为可结束的(finalizable)。3 当heap中的new String(abc)对象的finalize()方法被运行而且该对象占用的内存被释放， abcSoftRef被添加到它的ReferenceQueue中。

WeakReference wr = new WeakReference(obj);    obj = null;    //等待一段时间，obj对象就会被垃圾回收   

在此例中，透过 get() 可以取得此 Reference 的所指到的对象，如果返回值为 null 的话，代表此对象已经被清除。这类的技巧，在设计 Optimizer 或 Debugger 这类的程序时常会用到，因为这类程序需要取得某对象的信息，但是不可以 影响此对象的垃圾收集。 1.4:虚引用 就是没有的意思，建立虚引用之后通过get方法返回结果始终为null,通过源代码你会发现,虚引用通向会把引用的对象写进referent,只是get方法返回结果为null.先看一下和gc交互的过程在说一下他的作用.   1.4.1 不把referent设置为null, 直接把heap中的new String(abc)对象设置为可结束的(finalizable).  1.4.2 与软引用和弱引用不同, 先把PhantomRefrence对象添加到它的ReferenceQueue中.然后在释放虚可及的对象. 

public static void main(String[] args) throws Exception {           String abc = new String(abc);           System.out.println(abc.getClass()   @   abc.hashCode());           final ReferenceQueue referenceQueue = new ReferenceQueue();           new Thread() {               public void run() {                   while (isRun) {                       Object o = referenceQueue.poll();                       if (o != null) {                           try {                               Field rereferent = Reference.class                                      .getDeclaredField(referent);                               rereferent.setAccessible(true);                               Object result = rereferent.get(o);                               System.out.println(gc will collect:                                        result.getClass()   @                                        result.hashCode());                           } catch (Exception e) {                               e.printStackTrace();                           }                       }                   }               }           }.start();           PhantomReference abcWeakRef = new PhantomReference(abc,                   referenceQueue);           abc = null;           Thread.currentThread().sleep(3000);           System.gc();           Thread.currentThread().sleep(3000);           isRun = false;       }       

}  bitmapFactoryOptions.inJustDecodeBounds = false; bmap = BitmapFactory.decodeFile(picture.getAbsolutePath(),         bitmapFactoryOptions); if(bmap != null){                    //ivwCouponImage.setImageBitmap(bmap);     return bmap; } return null; 

@Override public void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,      WindowManager.LayoutParams.FLAG_FULLSCREEN);      setContentView(R.layout.photoscan);     Intent intent = this.getIntent();     if(intent != null){         if(intent.getBundleExtra(bundle) != null){             Bundle bundle = intent.getBundleExtra(bundle);             path = bundle.getString(path);             shopType = bundle.getString(shopType);         }     }     init(); } private void init(){     imageCache = new HashMap>();      gallery = (Gallery)findViewById(R.id.gallery);      ImageList = getSD();      if(ImageList.size() == 0){         Toast.makeText(getApplicationContext(), 无照片，请返回拍照后再使用预览, Toast.LENGTH_SHORT).show();         return ;      }      adapter = new ImageAdapter(this, ImageList);      gallery.setAdapter(adapter);      gallery.setOnItemLongClickListener(longlistener); } /**  * Gallery长按事件操作实现  */ private OnItemLongClickListener longlistener = new OnItemLongClickListener() {     @Override     public boolean onItemLongClick(AdapterView parent, View view,             final int position, long id) {         //此处添加长按事件删除照片实现         AlertDialog.Builder dialog = new AlertDialog.Builder(PhotoScanActivity.this);         dialog.setIcon(R.drawable.warn);         dialog.setTitle(删除提示);         dialog.setMessage(你确定要删除这张照片吗？);         dialog.setPositiveButton(确定, new DialogInterface.OnClickListener() {             @Override             public void onClick(DialogInterface dialog, int which) {                 File file = new File(it.get(position));                 boolean isSuccess;                 if(file.exists()){                     isSuccess = file.delete();                     if(isSuccess){                         ImageList.remove(position);                         adapter.notifyDataSetChanged();                         //gallery.setAdapter(adapter);                         if(ImageList.size() == 0){                             Toast.makeText(getApplicationContext(), getResources().getString(R.string.phoSizeZero), Toast.LENGTH_SHORT).show();                         }                         Toast.makeText(getApplicationContext(), getResources().getString(R.string.phoDelSuccess), Toast.LENGTH_SHORT).show();                     }                 }             }         });         dialog.setNegativeButton(取消,new DialogInterface.OnClickListener() {             @Override             public void onClick(DialogInterface dialog, int which) {                 dialog.dismiss();             }         });         dialog.create().show();         return false;     } }; /**  * 获取SD卡上的所有图片文件  * @return  */ private List getSD() {     /* 设定目前所在路径 */     File fileK ;     it = new ArrayList();     if(newadd.equals(shopType)){           //如果是从查看本人新增列表项或商户列表项进来时         fileK = new File(ApplicationData.TEMP);     }else{         //此时为纯粹新增         fileK = new File(path);     }     File[] files = fileK.listFiles();     if(files != null && files.length>0){         for(File f : files ){             if(getImageFile(f.getName())){                 it.add(f.getPath());                 Options bitmapFactoryOptions = new BitmapFactory.Options();                 //下面这个设置是将图片边界不可调节变为可调节                 bitmapFactoryOptions.inJustDecodeBounds = true;                 bitmapFactoryOptions.inSampleSize = 5;                 int outWidth  = bitmapFactoryOptions.outWidth;                 int outHeight = bitmapFactoryOptions.outHeight;                 float imagew = 150;                 float imageh = 150;                 int yRatio = (int) Math.ceil(bitmapFactoryOptions.outHeight                         / imageh);                 int xRatio = (int) Math                         .ceil(bitmapFactoryOptions.outWidth / imagew);                 if (yRatio > 1 || xRatio > 1) {                     if (yRatio > xRatio) {                         bitmapFactoryOptions.inSampleSize = yRatio;                     } else {                         bitmapFactoryOptions.inSampleSize = xRatio;                     }                 }                  bitmapFactoryOptions.inJustDecodeBounds = false;                 bitmap = BitmapFactory.decodeFile(f.getPath(),                         bitmapFactoryOptions);                 //bitmap = BitmapFactory.decodeFile(f.getPath());                  srf = new SoftReference(bitmap);                 imageCache.put(f.getName(), srf);             }         }     }     return it; } /**  * 获取图片文件方法的具体实现   * @param fName  * @return  */ private boolean getImageFile(String fName) {     boolean re;     /* 取得扩展名 */     String end = fName             .substring(fName.lastIndexOf(.)   1, fName.length())             .toLowerCase();     /* 按扩展名的类型决定MimeType */     if (end.equals(jpg) || end.equals(gif) || end.equals(png)             || end.equals(jpeg) || end.equals(bmp)) {         re = true;     } else {         re = false;     }     return re; } public class ImageAdapter extends BaseAdapter{     /* 声明变量 */     int mGalleryItemBackground;     private Context mContext;     private List lis;     /* ImageAdapter的构造符 */     public ImageAdapter(Context c, List li) {         mContext = c;         lis = li;         TypedArray a = obtainStyledAttributes(R.styleable.Gallery);         mGalleryItemBackground = a.getResourceId(R.styleable.Gallery_android_galleryItemBackground, 0);         a.recycle();     }     /* 几定要重写的方法getCount,传回图片数目 */     public int getCount() {         return lis.size();     }     /* 一定要重写的方法getItem,传回position */     public Object getItem(int position) {         return lis.get(position);     }     /* 一定要重写的方法getItemId,传并position */     public long getItemId(int position) {         return position;     }     /* 几定要重写的方法getView,传并几View对象 */     public View getView(int position, View convertView, ViewGroup parent) {         System.out.println(lis: lis);         File file = new File(it.get(position));         SoftReference srf = imageCache.get(file.getName());         Bitmap bit = srf.get();         ImageView i = new ImageView(mContext);         i.setImageBitmap(bit);         i.setScaleType(ImageView.ScaleType.FIT_XY);         i.setLayoutParams( new Gallery.LayoutParams(WindowManager.LayoutParams.WRAP_CONTENT,                 WindowManager.LayoutParams.WRAP_CONTENT));         return i;     } } 

/** 这个地方大家别搞混了，为了方便小马把两个贴一起了，使用的时候记得分开使用 * 以最省内存的方式读取本地资源的图片  */   public static Bitmap readBitMap(Context context, int resId){       BitmapFactory.Options opt = new BitmapFactory.Options();       opt.inPreferredConfig = Bitmap.Config.RGB_565;       opt.inPurgeable = true;      opt.inInputShareable = true;         //获取资源图片      InputStream is = context.getResources().openRawResource(resId);          return BitmapFactory.decodeStream(is,null,opt);