近来借助网络研究了一下MD5对文件的加密，顺便也总结一下对字符串和byte数组的加密，现贴出代码：
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;
/**
* MD5工具类
*
* @author 高焕杰
*/
public class MD5Util {
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;
/**
* MessageDigest初始化
*
* @author 高焕杰
*/
static {
try {
messagedigest = MessageDigest.getInstance("MD5");
} catch (NoSuchAlgorithmException e) {
System.err.println("MD5FileUtil messagedigest初始化失败");
e.printStackTrace();
}
}
/**
* 对文件进行MD5加密
*
* @author 高焕杰
*/
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());
}
/**
* 对字符串进行MD5加密
*
* @author 高焕杰
*/
public static String getMD5String(String s) {
return getMD5String(s.getBytes());
}
/**
* 对byte类型的数组进行MD5加密
*
* @author 高焕杰
*/
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++) {
char c0 = hexDigits[(bytes[l] & 0xf0) >> 4];
char c1 = hexDigits[bytes[l] & 0xf];
stringbuffer.append(c0);
stringbuffer.append(c1);
}
return stringbuffer.toString();
}
public static void main(String[] args) throws IOException {
String filePath = "D:\\死亡飞车.rmvb";
long fileBegin = System.currentTimeMillis();
System.out.println("文件加密结果为："+getFileMD5String(new File(filePath)));
long fileEnd = System.currentTimeMillis();
System.out.println("文件加密耗时:" + ((fileEnd - fileBegin) / 1000) + "s");
}
}
对文件、字符串和byte数组进行MD5加密,布布扣,bubuko.com
原文地址：http://blog.csdn.net/gaohuanjie/article/details/26485123
