计算文件MD5

import java.io.File;import java.io.FileInputStream;import java.math.BigInteger;import java.security.MessageDigest;/** * Created by guoliang.wgl on 2016/10/19. */public class Md5 {    public static String getFileMD5(File file) {        if (!file.isFile()) {            return null;        }        MessageDigest digest = null;        FileInputStream in = null;        byte buffer[] = new byte[1024];        int len;        try {            digest = MessageDigest.getInstance("MD5");            in = new FileInputStream(file);            while ((len = in.read(buffer, 0, 1024)) != -1) {                digest.update(buffer, 0, len);            }            in.close();        } catch (Exception e) {            e.printStackTrace();            return null;        }        BigInteger bigInt = new BigInteger(1, digest.digest());        return bigInt.toString(16);    }}