Md5之Java封装

package api.xxx.utils;

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

public class MD5 {
	
	private static char md5Chars[] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
	
	public static String md5(String str) {
	    MessageDigest md5 = getMD5Instance();
	    md5.update(str.getBytes());
	    byte[] digest = md5.digest();
	    char[] chars = toHexChars(digest);
	    return new String(chars);
	}
	
	private static MessageDigest getMD5Instance() {
	    try {
	        return MessageDigest.getInstance("MD5");
	    } catch (NoSuchAlgorithmException ignored) {
	        throw new RuntimeException(ignored);
	    }
	}
	
	private static char[] toHexChars(byte[] digest) {
	    char[] chars = new char[digest.length * 2];
	    int i = 0;
	    for (byte b : digest) {
	        char c0 = md5Chars[(b & 0xf0) >> 4];
	        chars[i++] = c0;
	        char c1 = md5Chars[b & 0xf];
	        chars[i++] = c1;
	    }
	    return chars;
	}
}