MessageDigest
http://linyu19872008.iteye.com/blog/1825343
- import java.io.File;
- import java.io.FileInputStream;
- import java.io.IOException;
- import java.nio.MappedByteBuffer;
- import java.nio.channels.FileChannel;
- import java.security.MessageDigest;
- import java.security.NoSuchAlgorithmException;
- import org.slf4j.Logger;
- import org.slf4j.LoggerFactory;
- public class MD5FileUtil {
- private static final Logger logger = LoggerFactory
- .getLogger(MD5FileUtil.class);
- protected static char hexDigits[] = { ‘0’, ‘1’, ‘2’, ‘3’, ‘4’, ‘5’, ‘6’,
- ‘7’, ‘8’, ‘9’, ‘a’, ‘b’, ‘c’, ‘d’, ‘e’, ‘f’ };
- protected static MessageDigest messagedigest = null;
- static {
- try {
- messagedigest = MessageDigest.getInstance(“MD5”);
- } catch (NoSuchAlgorithmException e) {
- logger.error(“MD5FileUtil messagedigest初始化失败”, e);
- }
- }
- public static String getFileMD5String(File file) throws IOException {
- FileInputStream in = new FileInputStream(file);
- FileChannel ch = in.getChannel();
- MappedByteBuffer byteBuffer = ch.map(FileChannel.MapMode.READ_ONLY, 0,
- file.length());
- messagedigest.update(byteBuffer);
- return bufferToHex(messagedigest.digest());
- }
- public static String getMD5String(String s) {
- return getMD5String(s.getBytes());
- }
- public static String getMD5String(byte[] bytes) {
- messagedigest.update(bytes);
- return bufferToHex(messagedigest.digest());
- }
- private static String bufferToHex(byte bytes[]) {
- return bufferToHex(bytes, 0, bytes.length);
- }
- private static String bufferToHex(byte bytes[], int m, int n) {
- StringBuffer stringbuffer = new StringBuffer(2 * n);
- int k = m + n;
- for (int l = m; l < k; l++) {
- appendHexPair(bytes[l], stringbuffer);
- }
- return stringbuffer.toString();
- }
- private static void appendHexPair(byte bt, StringBuffer stringbuffer) {
- char c0 = hexDigits[(bt & 0xf0) >> 4];
- char c1 = hexDigits[bt & 0xf];
- stringbuffer.append(c0);
- stringbuffer.append(c1);
- }
- public static boolean checkPassword(String password, String md5PwdStr) {
- String s = getMD5String(password);
- return s.equals(md5PwdStr);
- }
- public static void main(String[] args) throws IOException {
- long begin = System.currentTimeMillis();
- File big = new File(“D:\\temp\\jre-7u11-linux-i586.tar.gz”);
- String md5 = getFileMD5String(big);
- long end = System.currentTimeMillis();
- System.out.println(“md5:” + md5);
- System.out.println(“time:” + ((end – begin) / 1000) + “s”);
- }
- }