import org.apache.commons.codec.binary.Hex;import org.apache.commons.codec.digest.DigestUtils;import org.apache.log4j.Logger;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.security.MessageDigest;import java.security.NoSuchAlgorithmException;/** * md5算法工具 */public class MD5BigFileUtil {    private final static Logger logger = Logger.getLogger(MD5BigFileUtil.class);    static MessageDigest md = null;    static {        try {            md = MessageDigest.getInstance("MD5");        } catch (NoSuchAlgorithmException ne) {            logger.error("NoSuchAlgorithmException: md5", ne);        }    }    /**     * 对一个文件求他的md5值     * @param f 要求md5值的文件     * @return md5串     */    public static String md5(File f) {        FileInputStream fis = null;        try {            fis = new FileInputStream(f);            //100KB each time            byte[] buffer = new byte[102400];            int length;            long loopCount = 0;            while ((length = fis.read(buffer)) != -1) {                md.update(buffer, 0, length);                loopCount++;            }                        logger.debug("read file to buffer loopCount:"+loopCount);            return new String(Hex.encodeHex(md.digest()));        } catch (FileNotFoundException e) {            logger.error("md5 file " + f.getAbsolutePath() + " failed:" + e.getMessage());            return null;        } catch (IOException e) {            logger.error("md5 file " + f.getAbsolutePath() + " failed:" + e.getMessage());            return null;        } finally {            try {                if (fis != null) fis.close();            } catch (IOException e) {                e.printStackTrace();            }        }    }    /**     * 求一个字符串的md5值     * @param target 字符串     * @return md5 value     */    public static String md5(String target) {        return DigestUtils.md5Hex(target);    }        public static void main(String[] args) {        long begin =System.currentTimeMillis();        System.out.println(md5(new File("G:/BT/PremierePro_6_LS7.7z")));        long end =System.currentTimeMillis();        System.out.println("time:"+((end-begin)/1000)+"s");                System.out.println(md5("hello world"));    }}