android 优化

1.图像缩放

private  void  compressImage(String pathName) {
        BitmapFactory.Options options =  new  BitmapFactory.Options();
        options.inSampleSize =  10 ;  // 为原来图形的1/10
        Bitmap bitmap  = BitmapFactory.decodeFile(pathName ,options);
        // 显示图像到控件
        ImageView imageView =  new  ImageView(getApplicationContext());
        imageView.setImageBitmap(bitmap);
        bitmap.recycle();
    }

2.及时释放对象

class  ImageManager{
    //实现统一管理位图资源
    private  WeakHashMap<Integer, WeakReference<Bitmap>> mBitmaps;
    private  WeakHashMap<Integer, WeakReference<Drawable>> mDrawable;
    private  boolean  mActive =  true ;
    public  ImageManager(){
        mBitmaps =  new  WeakHashMap<Integer, WeakReference<Bitmap>>();
        mDrawable =  new  WeakHashMap<Integer, WeakReference<Drawable>>();
    }
    public   Bitmap  getmBitmaps( int  resource) {
        if  (mActive) {
            if  (!mBitmaps.containsKey(resource)) {
                mBitmaps.put(resource,  new  WeakReference<Bitmap>(BitmapFactory.decodeResource(getResources(), resource)));
                return  ((WeakReference<Bitmap>)mBitmaps.get(resource)).get();
            }
        }
        return   null ;
    }

    public  Drawable getDrawable( int  resource){
        if  (mActive) {
            if  (!mDrawable.containsKey(resource)) {
                mDrawable.put(resource,  new  WeakReference<Drawable>(getResources().getDrawable(resource)));
                return  ((WeakReference<Drawable>)mDrawable.get(resource)).get();
            }
        }

        return  null ;
    }
    public  void  recycleBitmaps(){
        Iterator iterator = mBitmaps.entrySet().iterator();
        while  (iterator.hasNext()) {
            Map.Entry type = (Map.Entry) iterator.next();
            ((WeakReference<Bitmap>)type.getValue()).get().recycle();

        }
    }
    private  ImageManager setActive( boolean  b) {
        // TODO Auto-generated method stub
        mActive = b;
        return  this ;

    }
    public  boolean  isActive(){
        return  mActive;
    }
}

3.

哟话网络连接, 

首先检测网络是否正常, 如没有网络就不执行相应的程序, 

检查网络连接的演示代码如下:

public  boolean  isConnected(){
        ConnectivityManager manager  = (ConnectivityManager) getSystemService(CONNECTIVITY_SERVICE);
        TelephonyManager telephonyManager = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE);
        NetworkInfo info = manager.getActiveNetworkInfo();
        if  (info== null ||!manager.getBackgroundDataSetting()) { // 无可用网络连接
            return  false ;
        }
        //网络类型判断, 只有3G或者wifi里进行数据更新
        int  netType = info.getType();
        int  netsubType = info.getSubtype();
        if  (netType == ConnectivityManager.TYPE_WIFI) {
            return  info.isConnected();
        }
        else  if  (netType == ConnectivityManager.TYPE_MOBILE&&netsubType == TelephonyManager.NETWORK_TYPE_UMTS&&!telephonyManager.isNetworkRoaming()){
            return  info.isConnected();
        } else {
            return  false ;
        }
    }

​