MessageDigest类封装得很不错，简单易用

不多说，直接上代码

import java.io.FileInputStream;

import java.security.MessageDigest;

import java.util.Scanner;

public class MD5Test {

public static void main(String[] args) {

System.out.print("输入文件名：");

Scanner inputFromConsole = new Scanner(System.in);

String filename = inputFromConsole.nextLine();

try (FileInputStream inputFromFile = new FileInputStream(filename)) {

MessageDigest md5 = MessageDigest.getInstance("MD5");

byte[] buffer = new byte[10 * 1024 * 1024];

int byteCount;

while ((byteCount = inputFromFile.read(buffer)) != -1) {

md5.update(buffer, 0, byteCount);

}

StringBuilder result = new StringBuilder();

byte[] digested = md5.digest();

for (byte e : digested) {

String hexStr = Integer.toHexString(e & 255);

if (hexStr.length() == 1)

result.append('0');

result.append(hexStr);

}

System.out.println(result);

} catch (Exception ex) {

ex.printStackTrace();

}

}

}