获取文件MD5值(JAVA代码)

package com.topcheer;

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;

public class GetFileMD5 {

/**

 * 获取压缩文件MD5值

 * David 2012-10-12 

 * 

 */

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) {
 
//System.err.println(GetFileMD5.class.getName()+"初始化失败，MessageDigest不支持MD5Util。");
e.printStackTrace();

  }

}

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 beginTime =System.currentTimeMillis();

   File fileZIP = new File("D:/TEST/IMG_0004.zip");

   String md5=getFileMD5String(fileZIP);

   long endTime =System.currentTimeMillis();

  System.out.println("md5:"+md5+"\n time:"+((endTime-beginTime)/1000)+"s");

}

}