Question

我的服务器限制图像大小上传图像（2MB）。我想将图像从Android设备上传到服务器。我想调整图像大小。我可以调整图像大小的最佳方法是什么？

Answer 1

使用以下代码。使用“MAX_IMAGE_SIZE”指定最大文件大小（千字节）。在这段代码中;首先我调整图像大小，然后压缩它。请参阅代码中的注释以更好地理解逻辑。

     public static String resizeAndCompressImageBeforeSend(Context context,String filePath,String fileName){
     final int MAX_IMAGE_SIZE = 700 * 1024; // max final file size in kilobytes

     // First decode with inJustDecodeBounds=true to check dimensions of image
     final BitmapFactory.Options options = new BitmapFactory.Options();
     options.inJustDecodeBounds = true;
     BitmapFactory.decodeFile(filePath,options);

     // Calculate inSampleSize(First we are going to resize the image to 800x800 image, in order to not have a big but very low quality image.
     //resizing the image will already reduce the file size, but after resizing we will check the file size and start to compress image
     options.inSampleSize = calculateInSampleSize(options, 800, 800);

     // Decode bitmap with inSampleSize set
     options.inJustDecodeBounds = false;
     options.inPreferredConfig= Bitmap.Config.ARGB_8888;

     Bitmap bmpPic = BitmapFactory.decodeFile(filePath,options);


     int compressQuality = 100; // quality decreasing by 5 every loop.
     int streamLength;
     do{
         ByteArrayOutputStream bmpStream = new ByteArrayOutputStream();
         Log.d("compressBitmap", "Quality: " + compressQuality);
         bmpPic.compress(Bitmap.CompressFormat.JPEG, compressQuality, bmpStream);
         byte[] bmpPicByteArray = bmpStream.toByteArray();
         streamLength = bmpPicByteArray.length;
         compressQuality -= 5;
         Log.d("compressBitmap", "Size: " + streamLength/1024+" kb");
     }while (streamLength >= MAX_IMAGE_SIZE);

     try {
         //save the resized and compressed file to disk cache
         Log.d("compressBitmap","cacheDir: "+context.getCacheDir());
         FileOutputStream bmpFile = new FileOutputStream(context.getCacheDir()+fileName);
         bmpPic.compress(Bitmap.CompressFormat.JPEG, compressQuality, bmpFile);
         bmpFile.flush();
         bmpFile.close();
     } catch (Exception e) {
         Log.e("compressBitmap", "Error on saving file");
     }
     //return the path of resized and compressed file
     return  context.getCacheDir()+fileName;
 }



 public static int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
     String debugTag = "MemoryInformation";
     // Image nin islenmeden onceki genislik ve yuksekligi
     final int height = options.outHeight;
     final int width = options.outWidth;
     Log.d(debugTag,"image height: "+height+ "---image width: "+ width);
     int inSampleSize = 1;

     if (height > reqHeight || width > reqWidth) {

         final int halfHeight = height / 2;
         final int halfWidth = width / 2;

         // Calculate the largest inSampleSize value that is a power of 2 and keeps both
         // height and width larger than the requested height and width.
         while ((halfHeight / inSampleSize) > reqHeight && (halfWidth / inSampleSize) > reqWidth) {
             inSampleSize *= 2;
         }
     }
     Log.d(debugTag,"inSampleSize: "+inSampleSize);
     return inSampleSize;
 }

Answer 2

Bitmap scaledBitmap = scaleDown(realImage, MAX_IMAGE_SIZE, true);

缩小方法：

public static Bitmap scaleDown(Bitmap realImage, float maxImageSize,
    boolean filter) {
float ratio = Math.min(
        (float) maxImageSize / realImage.getWidth(),
        (float) maxImageSize / realImage.getHeight());
int width = Math.round((float) ratio * realImage.getWidth());
int height = Math.round((float) ratio * realImage.getHeight());

Bitmap newBitmap = Bitmap.createScaledBitmap(realImage, width,
        height, filter);
return newBitmap;

}

Answer 3

您也可以在将图像编码为字符串，然后压缩其中的字节，然后在保存图像之前计算所需的长度，然后执行此操作。在这种情况下，如果太大，将迫使用户更改图像。我以为您已经对图像进行了编码。

     long myBitmapLength = myEncodedImage.getBytes().length/1024;
       if(myBitmapLength < 200){
           //allow saving 
     }

[Android] -Resize image上传到服务器

3 个答案: