上传图片,在线地址获取文件大小,md5(32位的)文件转码

1.上传图片

 private void himages(MultipartFile multipartFile){
        try {
            if (multipartFile.isEmpty()) {
                return ResultVo.failure("请选择文件");
            }
            // 获取文件的名称
            String originalFilename = multipartFile.getOriginalFilename();
            // 文件后缀 例如：.png
            String fileSuffix = originalFilename.substring(originalFilename.lastIndexOf("."));
            // uuid 生成文件名
            String uuid = String.valueOf(UUID.randomUUID());
            // 根路径，在 resources/static/upload
            String basePath = ResourceUtils.getURL("classpath:static/ltimages/").getPath();
            // 新的文件名，使用uuid生成文件名
            String fileName = uuid + fileSuffix;
            // 创建新的文件
            File fileExist = new File(basePath);
            // 文件夹不存在，则新建
            System.out.println("是否存在:=="+fileExist.exists());
            if (!fileExist.exists()) {
                fileExist.mkdirs();
            }
            // 获取文件对象
            File file = new File(basePath, fileName);
            // 完成文件的上传
            multipartFile.transferTo(file);
            System.out.println("文件上传完成!");
//            resultVo.setData("http:/127.0.0.1:8070/static/images/"+uuid +fileSuffix);
//            http://makers.zcwjvr.com:9010/static/ltimages/bdcf1a7b-3389-4300-a992-9887d9319de9.jpg
            System.out.println(uuid +fileSuffix);
            return resultVo;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return ResultVo.failure("上传失败");
    }

2.通过在线地址获取文件大小

/**
     * 获取网络文件大小
     */
    private long getFileLength(String downloadUrl) throws IOException{
        if(downloadUrl == null || "".equals(downloadUrl)){
            return 0L ;
        }
        URL url = new URL(downloadUrl);
        HttpURLConnection conn = null;
        try {
            conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("HEAD");
            conn.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows 7; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/47.0.2526.73 Safari/537.36 YNoteCef/5.8.0.1 (Windows)");
            return (long) conn.getContentLength();
        } catch (IOException e) {
            return 0L;
        } finally {
            conn.disconnect();
        }
    }

3.md5(32位的)文件转码

//filename文件根路径
public  String getMD5Checksum(String filename) throws Exception {
        byte[] b = createChecksum(filename);
        String result = "";

        for (int i=0; i < b.length; i++) {
            result += Integer.toString( ( b[i] & 0xff ) + 0x100, 16).substring(1);//加0x100是因为有的b[i]的十六进制只有1位
        }
        return result;
    }


public  byte[] createChecksum(String filename) throws Exception {
        InputStream fis =  new FileInputStream(filename);          //<span style="color: rgb(51, 51, 51); font-family: arial; font-size: 13px; line-height: 20px;">将流类型字符串转换为String类型字符串</span>

        byte[] buffer = new byte[1024];
        MessageDigest complete = MessageDigest.getInstance("MD5"); //如果想使用SHA-1或SHA-256，则传入SHA-1,SHA-256
        int numRead;

        do {
            numRead = fis.read(buffer);    //从文件读到buffer，最多装满buffer
            if (numRead > 0) {
                complete.update(buffer, 0, numRead);  //用读到的字节进行MD5的计算，第二个参数是偏移量
            }
        } while (numRead != -1);

        fis.close();
        return complete.digest();
    }