Spring 的 DigestUtils 实现 md5 码加密方法

Spring 的 DigestUtils 实现 md5 码加密方法

使用 DigestUtils 方法达到对数据进行 md5 加密的效果。

常用的 md2 md5 sha sha1 sha256 sha384 sha512 加密算法。

什么是 DigestUtils 工具类

DigestUtils 是一个算法工具类，Apache DigestUtils 线程安全的类来进行计算一个字符串的 MD5 值。

以下是 DigestUtils 源码。

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//

package org.springframework.util;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public abstract class DigestUtils {
    private static final String MD5_ALGORITHM_NAME = "MD5";
    private static final char[] HEX_CHARS = new char[]{'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};

    public DigestUtils() {
    }

    public static byte[] md5Digest(byte[] bytes) {
        return digest("MD5", bytes);
    }

    public static String md5DigestAsHex(byte[] bytes) {
        return digestAsHexString("MD5", bytes);
    }

    public static StringBuilder appendMd5DigestAsHex(byte[] bytes, StringBuilder builder) {
        return appendDigestAsHex("MD5", bytes, builder);
    }

    private static MessageDigest getDigest(String algorithm) {
        try {
            return MessageDigest.getInstance(algorithm);
        } catch (NoSuchAlgorithmException var2) {
            throw new IllegalStateException("Could not find MessageDigest with algorithm \"" + algorithm + "\"", var2);
        }
    }

    private static byte[] digest(String algorithm, byte[] bytes) {
        return getDigest(algorithm).digest(bytes);
    }

    private static String digestAsHexString(String algorithm, byte[] bytes) {
        char[] hexDigest = digestAsHexChars(algorithm, bytes);
        return new String(hexDigest);
    }

    private static StringBuilder appendDigestAsHex(String algorithm, byte[] bytes, StringBuilder builder) {
        char[] hexDigest = digestAsHexChars(algorithm, bytes);
        return builder.append(hexDigest);
    }

    private static char[] digestAsHexChars(String algorithm, byte[] bytes) {
        byte[] digest = digest(algorithm, bytes);
        return encodeHex(digest);
    }

    private static char[] encodeHex(byte[] bytes) {
        char[] chars = new char[32];

        for(int i = 0; i < chars.length; i += 2) {
            byte b = bytes[i / 2];
            chars[i] = HEX_CHARS[b >>> 4 & 15];
            chars[i + 1] = HEX_CHARS[b & 15];
        }

        return chars;
    }
}

对字符串进行加密

测试用例：

// 要加密的字符串
String str = "HrfAC7pjTUeAXzm5S+DCdA==";
String md5SessionKey = DigestUtils.md5DigestAsHex(str.getBytes());

# 输出：0bc4fff57a08ec795e14a19accdb114b