在Java中，可以使用MessageDigest类进行SHA哈希处理 。 在本文中，我们将向您展示如何使用SHA-256算法对字符串进行哈希处理并生成文件的校验和。

1. MessageDigest

1.1散列字符串。

package com.mkyong.hashing;import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;public class PasswordSha256 {public static void main(String[] args) throws NoSuchAlgorithmException {String password = "123456";MessageDigest md = MessageDigest.getInstance("SHA-256");byte[] hashInBytes = md.digest(password.getBytes(StandardCharsets.UTF_8));// bytes to hexStringBuilder sb = new StringBuilder();for (byte b : hashInBytes) {sb.append(String.format("%02x", b));}System.out.println(sb.toString());}}

输出量

8d969eef6ecad3c29a3a629280e686cf0c3f5d5a86aff3ca12020c923adc6c92

1.2文件校验和。

123456

package com.mkyong.hashing;import java.io.FileInputStream;
import java.io.IOException;
import java.security.DigestInputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;public class FileCheckSum {public static void main(String[] args) throws NoSuchAlgorithmException, IOException {MessageDigest md = MessageDigest.getInstance("SHA-256");byte[] hashInBytes = checksum("d:\\server.log", md);System.out.println(bytesToHex(hashInBytes));}private static byte[] checksum(String filepath, MessageDigest md) throws IOException {try (DigestInputStream dis = new DigestInputStream(new FileInputStream(filepath), md)) {while (dis.read() != -1) ; //empty loop to clear the datamd = dis.getMessageDigest();}return md.digest();}private static String bytesToHex(byte[] hashInBytes) {StringBuilder sb = new StringBuilder();for (byte b : hashInBytes) {sb.append(String.format("%02x", b));}return sb.toString();}}

输出量

8d969eef6ecad3c29a3a629280e686cf0c3f5d5a86aff3ca12020c923adc6c92

2. Apache Commons编解码器

或者，尝试使用此Apache Commons Codecs库进行哈希处理。

<dependency><groupId>commons-codec</groupId><artifactId>commons-codec</artifactId><version>1.11</version></dependency>

2.1散列字符串。

package com.mkyong.hashing;import org.apache.commons.codec.digest.DigestUtils;public class PasswordSha256 {public static void main(String[] args) {String password = "123456";String result = DigestUtils.sha256Hex(password);System.out.println(result);}}

输出量

8d969eef6ecad3c29a3a629280e686cf0c3f5d5a86aff3ca12020c923adc6c92

2.2文件校验和。

package com.mkyong.hashing;import org.apache.commons.codec.digest.DigestUtils;import java.io.FileInputStream;
import java.io.IOException;public class FileCheckSum {public static void main(String[] args) throws IOException {String result = DigestUtils.sha256Hex(new FileInputStream("d:\\server.log"));System.out.println(result);}}

输出量

8d969eef6ecad3c29a3a629280e686cf0c3f5d5a86aff3ca12020c923adc6c92

参考文献

1. Apache Commons编解码器
2. Java –如何将字节转换为十六进制
3. 维基百科– SHA-2
4. MessageDigest JavaDoc

翻译自: https://mkyong.com/java/java-sha-hashing-example/