MD5使用(密码加密和文件加密)

import org.springframework.web.multipart.MultipartFile;
 
import java.io.IOException;
import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
 
/**
 * MD5加密工具
 * @Author ChenWenChao
 */
public final class Md5Utils {
    private final static String MD5 ="MD5";
    private final static char[] HEX_DIGITS =
            {'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f'};
 
    /**
     * 密码加密工具
     * @param username 用户名
     * @param password 密码
     * @return 返回密文
     */
    public static String getPassword(String username, String password) {
        String passwordMd5 = encode(MD5, password);
        return encode(MD5, passwordMd5 + username);
    }
 
    /**
     * 加密方式
     * @param algorithm 加密方式 MD5
     * @param str 加密数据
     * @return
     */
    public static String encode(String algorithm, String str) {
        if (str ==null) {
            return null;
        }
        try {
            MessageDigest messageDigest = MessageDigest.getInstance(algorithm);
            messageDigest.update(str.getBytes());
            return getFormattedText(messageDigest.digest());
        }catch (Exception e) {
            throw new RuntimeException(e);
        }
 
    }
 
    private static String getFormattedText(byte[] bytes) {
        int len = bytes.length;
        StringBuilder buf =new StringBuilder(len *2);
        // 把密文转换成十六进制的字符串形式
        for (int j =0; j < len; j++) {
            buf.append(HEX_DIGITS[(bytes[j] <<4) &0x0f]);
            buf.append(HEX_DIGITS[bytes[j] &0x0f]);
        }
        return buf.toString();
    }
 
    /**
     * 文件md5加密
     * @param file
     * @return 返回文件校验码
     */
    public static String getFileMd5Code(MultipartFile file) {
        byte[] fileBytes =new byte[0];
        try {
            fileBytes = file.getBytes();
        }catch (IOException e) {
            e.printStackTrace();
        }
        MessageDigest md5 =null;
        try {
            md5 = MessageDigest.getInstance(MD5);
        }catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        byte[] digest = md5.digest(fileBytes);
        return new BigInteger(1, digest).toString(16);
    }
}