android 記憶體溢出

標籤：

參考：http://1002878825-qq-com.iteye.com/blog/1735356

出現情況：

1.使用大圖片，沒有及時recycle。
　　4.0後bitmap.option 中有 inPurgeable 記憶體不足可以回收,之前版本必須自己回收

解決：1.option 減小圖片載入 2.使用軟引用，及時recycle

2.listview的convertView 以及未用holder機制的運用

　　原因：contentView 系統已經緩衝

解決：1.holder 判斷 contentView是會否為空白

　　   2.提高順滑度listview lazy loading data ----- 參考資料：api demo list 13 滑動時不賦值

public class List13 extends ListActivity implements ListView.OnScrollListener {    private TextView mStatus;        private boolean mBusy = false;        /**     * Will not bind views while the list is scrolling     *      */    private class SlowAdapter extends BaseAdapter {        private LayoutInflater mInflater;                public SlowAdapter(Context context) {            mInflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);        }        /**         * The number of items in the list is determined by the number of speeches         * in our array.         *          * @see android.widget.ListAdapter#getCount()         */        public int getCount() {            return mStrings.length;        }        /**         * Since the data comes from an array, just returning the index is         * sufficent to get at the data. If we were using a more complex data         * structure, we would return whatever object represents one row in the         * list.         *          * @see android.widget.ListAdapter#getItem(int)         */        public Object getItem(int position) {            return position;        }        /**         * Use the array index as a unique id.         *          * @see android.widget.ListAdapter#getItemId(int)         */        public long getItemId(int position) {            return position;        }        /**         * Make a view to hold each row.         *          * @see android.widget.ListAdapter#getView(int, android.view.View,         *      android.view.ViewGroup)         */        public View getView(int position, View convertView, ViewGroup parent) {            TextView text;                        if (convertView == null) {                text = (TextView)mInflater.inflate(android.R.layout.simple_list_item_1, parent, false);            } else {                text = (TextView)convertView;            }            if (!mBusy) {                text.setText(mStrings[position]);                // Null tag means the view has the correct data                text.setTag(null);            } else {                text.setText("Loading...");                // Non-null tag means the view still needs to load it‘s data                text.setTag(this);            }            return text;        }    }        @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.list_13);        mStatus = (TextView) findViewById(R.id.status);        mStatus.setText("Idle");                // Use an existing ListAdapter that will map an array        // of strings to TextViews        setListAdapter(new SlowAdapter(this));                getListView().setOnScrollListener(this);    }            public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount,            int totalItemCount) {    }        public void onScrollStateChanged(AbsListView view, int scrollState) {        switch (scrollState) {        case OnScrollListener.SCROLL_STATE_IDLE:            mBusy = false;                        int first = view.getFirstVisiblePosition();            int count = view.getChildCount();            for (int i=0; i<count; i++) {                TextView t = (TextView)view.getChildAt(i);                if (t.getTag() != null) {                    t.setText(mStrings[first + i]);                    t.setTag(null);                }            }                        mStatus.setText("Idle");            break;        case OnScrollListener.SCROLL_STATE_TOUCH_SCROLL:            mBusy = true;            mStatus.setText("Touch scroll");            break;        case OnScrollListener.SCROLL_STATE_FLING:            mBusy = true;            mStatus.setText("Fling");            break;        }    }

View Code

3.單個頁面，橫豎屏切換N次後

　　解決：1.去除xml中相關設定，改在程式中設定背景圖（放在onCreate()方法中）：
　　　　　2. 跟上面方法相似，直接把xml設定檔載入成view 再放到一個容器裡，然後直接調用 this.setContentView(View view)方法，避免xml的重複載入

　　　　　3.Activity中添加了 android:configChanges屬性，目的是當所指定屬性(Configuration Changes)發生改變時，通知程式調用 onConfigurationChanged()函數

解決通用方法：

1.SoftReference 和 WeakReference的使用

2.壓縮圖片參考解決bitmap章節

3.修改虛擬機器參數 VMRuntime.getRuntime().setTargetHeapUtilization(0.75); 

4.不要為Context長期儲存引用(生命週期結束處理掉)

5.盡量用ApplicationContext

6.記憶體回收行程並不保證能準確回收記憶體，這樣在使用自己需要的內容時，主要生命週期和及時釋放掉不需要的對象。盡量在Activity的生命週期結束時，在onDestroy中把我們做引用的其他對象做釋放，比如：cursor.close()。

 

android 記憶體溢出