1.壓縮到指定尺寸

//使用Bitmap加Matrix來縮放
    public static Drawable resizeImage(Bitmap bitmap, int w, int h) 
    {  
        Bitmap BitmapOrg = bitmap;  
        int width = BitmapOrg.getWidth();  
        int height = BitmapOrg.getHeight();  
        int newWidth = w;  
        int newHeight = h;  

        float
 
 scaleWidth = ((float) newWidth) / width;  
        float scaleHeight = ((float) newHeight) / height;  

        Matrix matrix = new Matrix();  
        matrix.postScale(scaleWidth, scaleHeight);  
        // if you want to rotate the Bitmap   
        // matrix.postRotate(45);   
        Bitmap resizedBitmap = Bitmap.createBitmap(BitmapOrg, 0
 
, 0, width,  
                        height, matrix, true);  
        return new BitmapDrawable(resizedBitmap);  
    }

優缺點分析:
優點 : 能將圖片壓縮導致定尺寸
缺點:比較耗費記憶體 要先獲取整個圖片載入到記憶體中 初始輸入的 Bitmap只能通過BitmapFactory.decodeFile(productPath);
原始圖片較大,會費記憶體

2.按照比例壓縮

//使用BitmapFactory.Options的inSampleSize引數來縮放
    public
 
 static Drawable resizeImage2(String path,
            int width,int height) 
    {
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;//不載入bitmap到記憶體中
        BitmapFactory.decodeFile(path,options); 
        int outWidth = options.outWidth;
        int outHeight = options.outHeight;
        options.inDither = false;
        options.inPreferredConfig = Bitmap.Config.ARGB_8888;
        options.inSampleSize = 1;

        if (outWidth != 0 && outHeight != 0 && width != 0 && height != 0) 
        {
            int sampleSize=(outWidth/width+outHeight/height)/2;
            Log.d(tag, "sampleSize = " + sampleSize);
            options.inSampleSize = sampleSize;
        }

        options.inJustDecodeBounds = false;
        return new BitmapDrawable(BitmapFactory.decodeFile(path, options));     
    }

優缺點分析:
優點 :比較身記憶體,開始不需要載入整個圖片到記憶體中.只獲取原始圖片的寬高就可以了~
缺點:只能按照幾分之幾壓縮
options.inSampleSize
取樣率只能是int值,寬高只能壓縮到原來的1/2;1/3等等~~