base64转MultipartFile并压缩得到压缩后对的MultipartFile

    net.coobird
    thumbnailator
    0.4.8



    org.springframework
    spring-test

package com.fillke.file.util;

import org.springframework.web.multipart.MultipartFile;
import sun.misc.BASE64Decoder;

import java.io.*;


public class BASE64DecodedMultipartFile implements MultipartFile {
    private final byte[] imgContent;
    private final String header;

    public BASE64DecodedMultipartFile(byte[] imgContent, String header) {
        this.imgContent = imgContent;
        this.header = header.split(";")[0];
    }

    @Override
    public String getName() {
        return System.currentTimeMillis() + Math.random() + "." + header.split("/")[1];
    }

    @Override
    public String getOriginalFilename() {
        return System.currentTimeMillis() + (int) Math.random() * 10000 + "." + header.split("/")[1];
    }

    @Override
    public String getContentType() {
        return header.split(":")[1];
    }

    @Override
    public boolean isEmpty() {
        return imgContent == null || imgContent.length == 0;
    }

    @Override
    public long getSize() {
        return imgContent.length;
    }

    @Override
    public byte[] getBytes() throws IOException {
        return imgContent;
    }

    @Override
    public InputStream getInputStream() throws IOException {
        return new ByteArrayInputStream(imgContent);
    }

    @Override
    public void transferTo(File file) throws IOException, IllegalStateException {
        new FileOutputStream(file).write(imgContent);
    }


    public static MultipartFile base64ToMultipart(String base64) {
        try {
            String[] baseStrs = base64.split(",");

            BASE64Decoder decoder = new BASE64Decoder();
            byte[] b = new byte[0];
            b = decoder.decodeBuffer(baseStrs[1]);

            for (int i = 0; i < b.length; ++i) {
                if (b[i] < 0) {
                    b[i] += 256;
                }
            }
            return new BASE64DecodedMultipartFile(b, baseStrs[0]);
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
    }
}

String base64 = "";
// 临时文件
File tempFile = null;
if (StrUtil.isNotBlank(base64 )) {
	// 将base64转成 MultipartFile
	MultipartFile multipartFile = BASE64DecodedMultipartFile.base64ToMultipart(deployProgram.getPic());
	
	// 压缩图片
	String originalFilename = multipartFile.getOriginalFilename();
	String prefix = originalFilename.substring(originalFilename.lastIndexOf("."));
	tempFile = File.createTempFile(UUID.randomUUID().toString(), prefix);
	// 需引入对应依赖
	Thumbnails.of(multipartFile.getInputStream())
		.scale(0.6) //图片大小（长宽）压缩比例 从0-1，1表示原图
		.outputQuality(0.6) //图片质量压缩比例 从0-1，越接近1质量越好
		.toFile(tempFile);
	MultipartFile reduceMultipartFile = new MockMultipartFile("file", tempFile.getName(), null, new FileInputStream(tempFile));
}
// 删除临时file
if (tempFile != null) {
	tempFile.deleteOnExit();
}