How to reduce the picture proportionally by Java

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Upload a file @ RequestParam (value= ", required=true) using the spring annotation. You cannot pass a null value when required is true, and vice versa; UploadFile.getOriginalFilename () gets the file name of the uploaded file; System.nanoTime () returns the nanosecond of the current time, which is used as the file name; FileUtils.writeByteArrayToFile () uploads the file to the local directory; uses BufferedImage to load the image into memory, and then modifies the image, such as resizing, graying, setting transparency, and so on.

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