关于二次采样

publicclass TwoImageUtils { publicstaticvoidloadImage(String path, final ImageView imageView) { new AsyncTask<String, Void, Bitmap>() { @Override protectedvoidonPostExecute(Bitmap bitmap) { super.onPostExecute(bitmap); if (bitmap != null) imageView.setImageBitmap(bitmap); else imageView.setImageResource(R.drawable.ic_launcher); } @Override protected Bitmap doInBackground(String...params) { try { String path = params[0]; URL url = new URL(path); HttpURLConnection connection = (HttpURLConnection) url.openConnection(); connection.setRequestMethod("GET"); connection.setConnectTimeout(5000); connection.setReadTimeout(5000);int code = connection.getResponseCode(); if (code == 200) { //得到图片数据 InputStream is = connection.getInputStream(); //BitmapFactory.decodeStream(is);//ARGB_888 一个像素占 4个字节 ARGB_565 一个像素占 2 个字节 Alpha Red、Green、Blue(颜色) BitmapFactory.Options options = new BitmapFactory.Options(); //在图片真正解析之前，不要解析图片数据，只需要告诉一下转换器，只要获取图片的像素(宽高) options.inJustDecodeBounds = true;//告诉BitmapFactory转换工厂不去真正解析图片只需要拿到图片宽高就行//假解析 API 有bug BitmapFactory.decodeStream(is,null, options);//压缩，根据图片采样率进行二次采样 100 * 100 是你所期望的具体图片尺寸//options.inSampleSize = 2; //采样用来计算图片的宽高(1920 * 1080 -> 1920 / 2 1080 / 2)//获取图片宽高，注意：图片的原始宽高int width = options.outWidth; int height = options.outHeight; System.out.println("宽:" + width + "高 ： " + height); //定义一个变量去记住我们采样率int inSampleSize = 1;//默认是1 ,即不对图片进行任何压缩if (width > 100 || height > 100) { int halfWidth = width / 2;int halfHeight = height / 2;while ((halfWidth / inSampleSize) >= 100 && (halfHeight / inSampleSize) >= 100) { //计算采样率 inSampleSize *= 2; } } //采样率改变了 options.inSampleSize = inSampleSize;// 8//图片压缩完之后，放行图片解析 options.inJustDecodeBounds = false;//告诉图片转换工厂，可以解析图片了//关闭之前的流is.close();//重新再去得到当前这张图片的字节流数据is = url.openStream();//开始解析图片 Bitmap bitmap = BitmapFactory.decodeStream(is,null, options);//关闭流is.close();// Bitmap bitmap = BitmapFactory.decodeStream(is);return bitmap; } } catch (Exception e) { e.printStackTrace(); } returnnull; } }.execute(path); }}