Java - Создать контрольную сумму файла с SHA и MD5
В этой статье мы покажем вам, как использовать алгоритм SHA-256 и MD5 для генерации контрольной суммы для файла.
-
MessageDigest.getInstance(“algorithm”)
-
Кодек Apache Commons
1. Дайджест сообщения
d:\server.log
hello world
1.1 Generate a file checksum with a SHA256 algorithm.
FileCheckSumSHA.java
package com.example.hashing;
import java.io.FileInputStream;
import java.io.IOException;
import java.security.DigestInputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
public class FileCheckSumSHA {
public static void main(String[] args) throws NoSuchAlgorithmException, IOException {
MessageDigest md = MessageDigest.getInstance("SHA-256"); //SHA, MD2, MD5, SHA-256, SHA-384...
String hex = checksum("d:\\server.log", md);
System.out.println(hex);
}
private static String checksum(String filepath, MessageDigest md) throws IOException {
// file hashing with DigestInputStream
try (DigestInputStream dis = new DigestInputStream(new FileInputStream(filepath), md)) {
while (dis.read() != -1) ; //empty loop to clear the data
md = dis.getMessageDigest();
}
// bytes to hex
StringBuilder result = new StringBuilder();
for (byte b : md.digest()) {
result.append(String.format("%02x", b));
}
return result.toString();
}
}
Выход
b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9
1.2 Generate a file checksum with a MD5 algorithm.
FileCheckSumMD5.java
package com.example.hashing;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
public class FileCheckSumMD5 {
public static void main(String[] args) throws NoSuchAlgorithmException, IOException {
MessageDigest md = MessageDigest.getInstance("MD5");
String hex = checksum("d:\\server.log", md);
System.out.println(hex);
}
private static String checksum(String filepath, MessageDigest md) throws IOException {
// DigestInputStream is better, but you also can hash file like this.
try (InputStream fis = new FileInputStream(filepath)) {
byte[] buffer = new byte[1024];
int nread;
while ((nread = fis.read(buffer)) != -1) {
md.update(buffer, 0, nread);
}
}
// bytes to hex
StringBuilder result = new StringBuilder();
for (byte b : md.digest()) {
result.append(String.format("%02x", b));
}
return result.toString();
}
}
Выход
5eb63bbbe01eeed093cb22bb8f5acdc3
2. Кодек Apache Commons
pom.xml
commons-codec commons-codec 1.11
2.1 File checksum.
FileCheckSum.java
package com.example.hashing;
import org.apache.commons.codec.digest.DigestUtils;
import java.io.FileInputStream;
import java.io.IOException;
public class App {
public static void main(String[] args) throws IOException {
String checksumSHA256 = DigestUtils.sha256Hex(new FileInputStream("d:\\server.log"));
System.out.println("checksumSHA256 : " + checksumSHA256);
String checksumMD5 = DigestUtils.md5Hex(new FileInputStream("d:\\server.log"));
System.out.println("checksumMD5 : " + checksumMD5);
}
}
Выход
checksumSHA256 : b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9 checksumMD5 : 5eb63bbbe01eeed093cb22bb8f5acdc3