方法 ： 传入文件路径和base64位的编码

/**
 * base64转为图片
 * @param path
 * 文件路径：到文件夹即可，代码里会在文件夹里生成对应的jpg文件
 * @param base64
 * @return
 */
public static String base64ToJpg(String path,String base64){
    // 判断文件路径是否存在
    File filePath = new File(path);
    if (!filePath.exists()){
        filePath.mkdirs();
    }
    // 创建文件
    String jpgFile = path + "\\" + UUID.randomUUID() + ".jpg";
    File file = new File(jpgFile);
    boolean jpgFileExist = false;
    try {
        jpgFileExist = file.createNewFile();
        log.info("jpg文件创建成功");
    } catch (IOException e) {
        log.info("jpg文件创建失败");
        e.printStackTrace();
    }
    if (jpgFileExist){
        // 解密
        Base64.Decoder decoder = Base64.getDecoder();
        // 去掉base64前缀 data:image/jpeg;base64,
        base64 = base64.substring(base64.indexOf(",", 1) + 1, base64.length());
        byte[] b = decoder.decode(base64);
        // 处理数据
        for (int i = 0; i < b.length; ++i) {
            if (b[i] < 0) {
                b[i] += 256;
            }
        }
        // 保存图片
        try {
            FileOutputStream out = new FileOutputStream(jpgFile);
            out.write(b);
            out.flush();
            out.close();
            // 写入成功返回文件路径
            return jpgFile;
        } catch (FileNotFoundException e) {
            log.info("文件未找到");
            e.printStackTrace();
        } catch (IOException e) {
            log.info("写入失败");
            e.printStackTrace();
        }
    }
    return "文件不存在";
}

public static void main(String[] args) {
Map<String, Object> imageCode = getImageCode();
log.info(imageCode.get(“imageCodeKey”).toString());
log.info(imageCode.get(“imageCodeBase64”).toString());
String base64 = imageCode.get(“imageCodeBase64”).toString();
String filePath = “C:\Users\Asus\Desktop\temp”;
String res = base64ToJpg(filePath, base64);
log.info(res);
}