//使用Bitmap加Matrix来缩放
    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);  
    }

//使用BitmapFactory.Options的inSampleSize参数来缩放
    public static Drawable resizeImage2(String path,
			int width,int height) 
    {
		BitmapFactory.Options options = new BitmapFactory.Options();
		options.inJustDecodeBounds = true;//不加载bitmap到内存中
		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));		
	}

Android图片缩放 指定尺寸