在 Java 中调整 base64 字符串图像的大小

Question

I'm trying to resize a Base64 String image with java and I have looked for different approaches without any result.

I was trying using the Cloudinary library but finally I noticed that it doesn't has support for Base64 Strings.

I also tried using

package com.rccl.middleware.kidsclub.engine.util;

import sun.misc.BASE64Decoder;
import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.IOException;

public class ResizeImage {
    private static final int IMG_WIDTH = 100;
    private static final int IMG_HEIGHT = 100;

    public static void main(String[] args) {
        String input = "data:image/jpeg;base64,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";
        // decode base64 encoded image
        try {
            BufferedImage image = ImageIO.read(new ByteArrayInputStream(input.getBytes()));
            resizeImage(image, image.getType());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static BufferedImage resizeImage(BufferedImage originalImage, int type) {
        BufferedImage resizedImage = new BufferedImage(IMG_WIDTH, IMG_HEIGHT, type);
        Graphics2D g = resizedImage.createGraphics();
        g.drawImage(originalImage, 0, 0, IMG_WIDTH, IMG_HEIGHT, null);
        g.dispose();

        return resizedImage;
    }

}

But I'm getting an NullPointerExepction, because in this line:

 BufferedImage image = ImageIO.read(new ByteArrayInputStream(decodedBytes));

The image object is null. I don't know if it is a good approach due to I don't have experience in this topic.

Any advices? Thanks.

Answer 1

I had the same problem. After I did some reading on the topic, I did the following:

First, I save the image in the file system (this could be saved on some temporary location if you don't need it). I have as an input the base64 string of the image to be saved (and later resized), its name (fileName) and the path on which to be saved. Note: the file name must contain the extension of the image as well.

    byte[] bytes = Base64.getDecoder().decode(base64);
    Path path = Paths.get(location, fileName);
    try {
        Files.write(path, bytes);
    } catch (IOException e) {
        // handle
    }

Now once we have saved the original, we receive the following input: the file path of the original (the image that we saved), the path on which to save the new resized image, the file name of the new scaled image and the width in pixels by which we want it scaled. The height will be automatically adjusted in this code, but otherwise it can be hard-coded instead as well if you need a specific height.

public boolean saveScaledImage(String originalFilePath, String path, String fileNameToSave, int width) {
    File input = new File(originalFilePath);
    try {
        BufferedImage image = ImageIO.read(input);
        BufferedImage resized = resize(image, width, width * image.getHeight() / image.getWidth());
        File output = new File(path, fileNameToSave);
        String[] parts = fileNameToSave.split("\\.");
        String extension = parts[parts.length - 1];
        ImageIO.write(resized, extension, output);
        return true;
    } catch (IOException e) {
        // handle
    }
}

private BufferedImage resize(BufferedImage img, int width, int height) {
    Image tmp = img.getScaledInstance(width, height, Image.SCALE_SMOOTH);
    BufferedImage resized = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
    Graphics2D g2d = resized.createGraphics();
    g2d.drawImage(tmp, 0, 0, null);
    g2d.dispose();
    return resized;
}

In the end, if you don't need the original you can delete it (in my case I needed it anyway).

Here are the used imports:

import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Base64;
import javax.imageio.ImageIO;

Reference that helped: https://memorynotfound.com/java-resize-image-fixed-width-height-example/