1.使用自定義工具類MD5Utils

package com.utils;

import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MD5Utils {
    public static String toMD5(String plainText) {
        byte[] secretBytes = null;
        try {
            secretBytes = MessageDigest.getInstance("md5"
 
).digest(
                    plainText.getBytes());
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException("沒有md5這個演算法！");
        }
        String md5code = new BigInteger(1, secretBytes).toString(16);// 16進位制數字
        // 如果生成數字未滿32位，需要前面補0
        for (int i = 0; i < 32
 
 - md5code.length(); i++) {
            md5code = "0" + md5code;
        }
        return md5code;
    }
}

String  md5=MD5Utils.toMD5("123456");

2. 使用commons-codec

String  md5=DigestUtils.md5Hex("123456");