安卓中關於圖片從網絡獲取，壓縮，上傳，下載，縮略圖，緩存的一些處理總結（四）

這裏根絕網上的一些文章寫了一個工具類  pictureSize 一般寫成1080*1920  這個數值越大圖片越清晰 加載需要的內存越多   請大家根據情況自行設定    這裏2個方法 一個是針對網上URL 一個是本地path

public static Bitmap downloadImgByUrl(String imgUrl, int pictureSize) {
        BufferedInputStream is = null;
        HttpURLConnection conn = null;
        try {
            URL url = new URL(imgUrl);
            conn = (HttpURLConnection) url.openConnection();
            is = new BufferedInputStream(conn.getInputStream());
            is.mark(is.available());
        } catch (IOException e) {
            e.printStackTrace();
        }
        Bitmap bitmap = null;
        BitmapFactory.Options opts = new BitmapFactory.Options();
        //2.爲位圖設置100K的緩存
        opts.inTempStorage = new byte[100 * 1024];
        //3.設置位圖顏色顯示優化方式
        opts.inPreferredConfig = Bitmap.Config.RGB_565;
        //4.設置圖片可以被回收，創建Bitmap用於存儲Pixel的內存空間在系統內存不足時可以被回收
        opts.inPurgeable = true;
        //6.設置解碼位圖的尺寸信息
        opts.inInputShareable = true;
        opts.inJustDecodeBounds = true;
//        bitmap=BitmapFactory.decodeStream(is, null, opts);
        opts.inSampleSize = computeSampleSize(opts, -1, pictureSize);
        opts.inJustDecodeBounds = false;
        try {
            bitmap = BitmapFactory.decodeStream(is, null, opts);
            is.reset();
            conn.disconnect();
        } catch (Exception e) {
            // TODO: handle exception
        }


        return bitmap;
    }

    public static Bitmap revitionImageSize(String filePath, int pictureSize) {
        Bitmap bitmap = null;
        BitmapFactory.Options opts = new BitmapFactory.Options();
        //2.爲位圖設置100K的緩存
        opts.inTempStorage = new byte[100 * 1024];
        //3.設置位圖顏色顯示優化方式
        opts.inPreferredConfig = Bitmap.Config.RGB_565;
        //4.設置圖片可以被回收，創建Bitmap用於存儲Pixel的內存空間在系統內存不足時可以被回收
        opts.inPurgeable = true;
        //6.設置解碼位圖的尺寸信息
        opts.inInputShareable = true;
        opts.inJustDecodeBounds = true;
        bitmap=BitmapFactory.decodeFile(filePath, opts);
        opts.inSampleSize = computeSampleSize(opts, -1, pictureSize);
        opts.inJustDecodeBounds = false;

        try {
            bitmap = BitmapFactory.decodeFile(filePath, opts);
        } catch (Exception e) {
            // TODO: handle exception
        }
        return bitmap;
    }

    public static int computeSampleSize(BitmapFactory.Options options, int minSideLength, int maxNumOfPixels) {
        int initialSize = computeInitialSampleSize(options, minSideLength, maxNumOfPixels);
        int roundedSize;
        if (initialSize <= 8) {
            roundedSize = 1;
            while (roundedSize < initialSize) {
                roundedSize <<= 1;
            }
        } else {
            roundedSize = (initialSize + 7) / 8 * 8;
        }
        return roundedSize;
    }

    private static int computeInitialSampleSize(BitmapFactory.Options options, int minSideLength, int maxNumOfPixels) {
        double w = options.outWidth;
        double h = options.outHeight;
        int lowerBound = (maxNumOfPixels == -1) ? 1 : (int) Math.ceil(Math.sqrt(w * h / maxNumOfPixels));
        int upperBound = (minSideLength == -1) ? 128 : (int) Math.min(Math.floor(w / minSideLength), Math.floor(h / minSideLength));
        if (upperBound < lowerBound) {
            // return the larger one when there is no overlapping zone.
            return lowerBound;
        }
        if ((maxNumOfPixels == -1) && (minSideLength == -1)) {
            return 1;
        } else if (minSideLength == -1) {
            return lowerBound;
        } else {
            return upperBound;
        }
    }