package com.imooc.util;
import java.io.File;
import java.io.FileInputStream;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.security.MessageDigest;
/**
* @author **
* @date 2018/6/9 10:05
*/
public final class Md5Util {
private static final char DIGITS[] = {
'0',
'1',
'2',
'3',
'4',
'5',
'6',
'7',
'8',
'9',
'a',
'b',
'c',
'd',
'e',
'f' };
/**
* 获取文件的MD5码
*
* @param absPath
* 文件路径
* @return 文件的MD5码
*/
public static String
getFileMD5(String absPath) {
try {
File file =
new File(absPath);
MessageDigest mdTemp = MessageDigest.getInstance(
"MD5");
FileInputStream fis =
new FileInputStream(file);
FileChannel filechannel = fis.getChannel();
MappedByteBuffer mbb = filechannel
.map(FileChannel.MapMode.READ_ONLY,
0, file.length());
mdTemp.update(mbb);
byte[] md = mdTemp.digest();
int j = md.length;
char str[] =
new char[j *
2];
int k =
0;
for (
int i =
0; i < j; i++) {
byte byte0 = md[i];
str[k++] = DIGITS[byte0 >>>
4 &
0xf];
str[k++] = DIGITS[byte0 &
0xf];
}
fis.close();
return new String(str);
}
catch (Exception e) {
return "";
}
}
/**
* 获取指定字符串的MD5码
*
* @param s 字符串
* @return 字符串的MD5码
*/
public static String
getMD5(String s) {
return getMD5WithSalt(s,
null);
}
/**
* 根据盐值获取指定字符串的MD5码
*
* @param s 字符串
* @return 字符串的MD5码
*/
public static String
getMD5WithSalt(String s, String salt) {
char hexDigits[] = {
'0',
'1',
'2',
'3',
'4',
'5',
'6',
'7',
'8',
'9',
'a',
'b',
'c',
'd',
'e',
'f' };
try {
MessageDigest digest = MessageDigest.getInstance(
"MD5");
digest.update(addSalt(s, salt).getBytes());
byte[] md = digest.digest();
int j = md.length;
char str[] =
new char[j *
2];
int k =
0;
for (
int i =
0; i < j; i++) {
byte byte0 = md[i];
str[k++] = hexDigits[byte0 >>>
4 &
0xf];
str[k++] = hexDigits[byte0 &
0xf];
}
return new String(str);
}
catch (Exception e) {
return null;
}
}
/**
* 为加密对象撒盐（盐值加密）
* @param object 待加密对象
* @param salt 盐（秘钥）
* @return 撒盐后的结果
*/
private static String
addSalt(String object, String salt) {
if(object ==
null){
object =
"";
}
if(salt ==
null ||
"".equals(salt)){
return object;
}
else {
return object +
"{"+ salt +
"}";
}
}
}
