代码:指定大小的图片

    /**
     * 从文件解析出Bitmap格式的图片
     * 
     * @param path
     * @param maxWidth
     * @param maxHeight
     * @return
     */
    public static Bitmap decodeFile(String path, int maxWidth, int maxHeight){
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        Bitmap image = null;
        image = BitmapFactory.decodeFile(path, options);
        double ratio = 1D;
        if (maxWidth > 0 && maxHeight <= 0) {
            // 限定宽度，高度不做限制
            ratio = Math.ceil(options.outWidth / maxWidth);
        } else if (maxHeight > 0 && maxWidth <= 0) {
            // 限定高度，不限制宽度
            ratio = Math.ceil(options.outHeight / maxHeight);
        } else if (maxWidth > 0 && maxHeight > 0) {
            // 高度和宽度都做了限制，这时候我们计算在这个限制内能容纳的最大的图片尺寸，不会使图片变形
            double _widthRatio = Math.ceil(options.outWidth / maxWidth);
            double _heightRatio = (double) Math.ceil(options.outHeight / maxHeight);
            ratio = _widthRatio > _heightRatio ? _widthRatio : _heightRatio;
        }
        if (ratio > 1) {
            options.inSampleSize = (int) ratio;
        }
        options.inSampleSize = calcScaleRatio(maxWidth, maxHeight, options.outWidth, options.outHeight);
        options.inJustDecodeBounds = false;
        options.inPreferredConfig = Bitmap.Config.RGB_565;
        image = BitmapFactory.decodeFile(path, options);
        return image;
    }