[Android] - 将图片上传到服务器

Question

我的服务器限制图片大小上传图片（2MB）。 我想从android设备上传图片到服务器。我想调整图像大小。什么是我可以调整图像大小的最佳方式？

Answer 1

使用下面的代码。使用“MAX_IMAGE_SIZE”，以千字节为单位指定最大文件大小。在这个代码中;首先我调整图像大小，然后压缩它。在代码中查看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); 

比例缩小方法：

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; 

}