java获取文 件的MD5值

有两种解决方案，一种是用MessageDigest来实现，另种是用org.apache.commons.codec.digest来实现，下面是代码：

package com.creditease.mobile.utils;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.math.BigInteger;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.security.MessageDigest;

import org.apache.commons.codec.digest.*;
import org.apache.commons.io.IOUtils;

public class MD5Util {
/**
* 用MessageDigest获取文件的md5值
* @param file
* @return
* @throws FileNotFoundException
*/
public static String getMd5ByMessageDigest(String filePath) throws FileNotFoundException {
File file = new File(filePath);
String value = null;
FileInputStream in = new FileInputStream(file);
try {
MappedByteBuffer byteBuffer = in.getChannel().map(
FileChannel.MapMode.READ_ONLY, 0, file.length());
MessageDigest md5 = MessageDigest.getInstance("MD5");
md5.update(byteBuffer);
BigInteger bi = new BigInteger(1, md5.digest());
value = bi.toString(16);
} catch (Exception e) {
e.printStackTrace();
} finally {
if (null != in) {
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return value;
}
/**
* 用DigestUtils去获取MD5值
* @param filePath
* @return
* @throws IOException
*/
public static String getMd5ByDigestUtils(String filePath) throws IOException{
FileInputStream fis = new FileInputStream(filePath);
String md5 = DigestUtils.md5Hex(IOUtils.toByteArray(fis));
IOUtils.closeQuietly(fis);
return md5;
}
public static void main(String[] args) throws IOException {
String path = "E:\\msdia80.dll";
int count = 3000;
String v = "";
long s1 = System.currentTimeMillis();
for(int i=0;i<count;i++){
v = getMd5ByMessageDigest(path);
}
long e1 = System.currentTimeMillis();
System.out.println("MD5:" + v.toUpperCase()+",耗时:"+(e1-s1)+"毫秒");

String v1 = "";
long s2 = System.currentTimeMillis();
for(int i=0;i<count;i++){
v1 = getMd5ByDigestUtils(path);
}
long e2 = System.currentTimeMillis();
System.out.println("MD5:"+v1+",耗时:"+(e2-s2)+"毫秒");
}

}

测试结果：



由此可以看出用jdk 的java.security.MessageDigest效率上要比org.apache.commons.codec.digest.*这个高一些。