生成文件或者字符的摘要校验码

   public static void main(String args[]){
        try{
            String myInfo = "我的测试摘要校验码";
            MessageDigest md = MessageDigest.getInstance("SHA-1");//SHA-256 SHA-512
            md.update(myInfo.getBytes(), 0, myInfo.getBytes().length);
            byte[] hashValue = md.digest();
            String hexValue = DigestUtils.sha1Hex(hashValue);
            System.out.println(hexValue);
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }

   @Test
    public void test2() throws IOException {

            InputStream in = null;
            try{
                MessageDigest md = MessageDigest.getInstance("SHA1");
                in = new FileInputStream("/usr/loacl/aa.txt");
                int blockSize = 131072;
                byte[] inBytes = new byte[blockSize];
                while (true){
                    int len = in.read(inBytes);
                    if (len == -1) {
                        break;
                    }
                    md.update(inBytes, 0, len);
                }
                byte[] hashValue = md.digest();
                String hexValue = DigestUtils.sha1Hex(hashValue);
                System.out.println(hexValue);
             }
            catch (Exception e) {
                e.printStackTrace();
            }finally {
                in.close();
            }
    }