java已经实现了MD5、SHA1算法。利用java.security.MessageDigest类就可以获取字符串和文件的MD5以及SHA1结果。
import java.io.File;
import java.io.FileInputStream;
import java.security.DigestInputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
public class FilesMds {
/**
* 字符串的MD5
* @param input
* @return
*/
public static String getStrMD5(String input) {
try {
// 拿到一个MD5转换器(如果想要SHA1参数换成”SHA1”)
MessageDigest messageDigest = MessageDigest.getInstance("MD5");
// 输入的字符串转换成字节数组
byte[] inputByteArray = input.getBytes();
// inputByteArray是输入字符串转换得到的字节数组
messageDigest.update(inputByteArray);
// 转换并返回结果,也是字节数组,包含16个元素
byte[] resultByteArray = messageDigest.digest();
// 字符数组转换成字符串返回
return byteArrayToHex(resultByteArray);
} catch (NoSuchAlgorithmException e) {
return null;
}
}
/**
* 文件MD5
* @param file
* @return
*/
public static String getFileMD52(File file) {
if (!file.isFile()) {
return null;
}
MessageDigest digest = null;
FileInputStream in = null;
DigestInputStream digestInputStream = null;
byte buffer[] = new byte[256 * 1024];
try {
digest = MessageDigest.getInstance("MD5");
in = new FileInputStream(file);
digestInputStream = new DigestInputStream(in, digest);
while (digestInputStream.read(buffer) > 0)
;
digest = digestInputStream.getMessageDigest();
byte[] resultByteArray = digest.digest();
return byteArrayToHex(resultByteArray);
} catch (Exception e) {
e.printStackTrace();
return null;
} finally {
try {
digestInputStream.close();
} catch (Exception e) {
}
try {
in.close();
} catch (Exception e) {
}
}
}
/**
* 将字节数组换成成16进制的字符串
* @param byteArray
* @return
*/
public static String byteArrayToHex(byte[] byteArray) {
// 首先初始化一个字符数组,用来存放每个16进制字符
char[] hexDigits = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
// new一个字符数组,这个就是用来组成结果字符串的(解释一下:一个byte是八位二进制,也就是2位十六进制字符(2的8次方等于16的2次方))
char[] resultCharArray = new char[byteArray.length * 2];
// 遍历字节数组,通过位运算(位运算效率高),转换成字符放到字符数组中去
int index = 0;
for (byte b : byteArray) {
resultCharArray[index++] = hexDigits[b >>> 4 & 0xf];
resultCharArray[index++] = hexDigits[b & 0xf];
}
// 字符数组组合成字符串返回
return new String(resultCharArray);
}
public static String md5MutiFile(MultipartFile file) {
String str = "";
try {
MessageDigest md = MessageDigest.getInstance("MD5");
md.update(file.getBytes());
byte b[] = md.digest();
int i;
StringBuffer buf = new StringBuffer("");
for (int offset = 0; offset < b.length; offset++) {
i = b[offset];
if (i < 0)
i += 256;
if (i < 16)
buf.append("0");
buf.append(Integer.toHexString(i));
}
str = buf.toString();
} catch (Exception e) {
e.printStackTrace();
}
System.out.println("MD5:" + str.toUpperCase());
return str.toUpperCase();
}
public static void main(String[] args) {
// TODO Auto-generated method stub
long startTime = System.currentTimeMillis();
try {
System.out.println(getStrMD5("hello world"));
System.out.println(getFileMD52(new File("D:\\test.txt")));
File file = new File("D:\\test.txt");
FileInputStream input = new FileInputStream(file);
MultipartFile multipartFile = new MockMultipartFile("file", file.getName(), "text/plain",
IOUtils.toByteArray(input));
} catch (Exception e) {
e.printStackTrace();
}
long endTime = System.currentTimeMillis();
System.out.println((endTime - startTime) / 1000);
}
}