java对base64的图片进行压缩

目标：用java将图片的base64码压缩到40kb以下。

依赖

  <!--  压缩图片-->

        <dependency>

            <groupId>net.coobird</groupId>

            <artifactId>thumbnailator</artifactId>

            <version>0.4.8</version>

        </dependency>

压缩的方法：

import net.coobird.thumbnailator.Thumbnails;

import org.springframework.stereotype.Service;

import sun.misc.BASE64Decoder;
import javax.imageio.ImageIO;

import java.awt.image.BufferedImage;

import java.io.ByteArrayInputStream;

import java.io.InputStream;

import org.apache.commons.codec.binary.Base64;

import java.io.*;
/*

   图片压缩

 */
@Service

public class Imageys {
/**

     * 压缩base64编码至40K以内

     * @param base64Img

     * @return

     */

    public   String resizeImageTo40K(String base64Img) {

        try{

            BASE64Decoder decoder = new BASE64Decoder();

            byte[] bytes1 = decoder.decodeBuffer(base64Img);

            InputStream stream = new ByteArrayInputStream(bytes1);

            BufferedImage src = ImageIO.read(stream);

            //BufferedImage output = Thumbnails.of(src).size(src.getWidth() / 3, src.getHeight() / 3).asBufferedImage();

            BufferedImage output = Thumbnails.of(src).size(50, 50).asBufferedImage();

            String base64 = imageToBase64(output);

            if (base64.length() - base64.length() / 8 * 2 > 40000) {

                output = Thumbnails.of(output).scale(1 / (base64.length() / 40000)).asBufferedImage();

                base64 = imageToBase64(output);

            }

            return base64;

        } catch (Exception e) {

            return base64Img;

        }

    }
// BufferedImage转换成base64，在这里需要设置图片格式，如下是jpg格式图片：

    public static String imageToBase64(BufferedImage bufferedImage) {

        Base64 encoder = new Base64();

        ByteArrayOutputStream baos = new ByteArrayOutputStream();

        try {

            ImageIO.write(bufferedImage, "jpg", baos);

        } catch (IOException e) {

        }

        return new String(encoder.encode((baos.toByteArray())));

    }
}

调用方法和输出结果

 //压缩图片

@Autowired
Imageys imageys;

String imageBase64 = "/9j/4AAQSkZJRgABAgAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDA.........";//此处省略

System.out.println("old:"+imageBase64.length());

imageBase64 = imageys.resizeImageTo40K(imageBase64);

System.out.println("new:"+imageBase64.length());

//输出结果
old:328724
new:7974

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