学步园

将加密后的数据转换为16进制32位的字符串：

	private static final char HEX_DIG[]={'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
	
	public static void main(String[] args) throws Exception{
		//初始化加密器
		MessageDigest  md5 = MessageDigest.getInstance("MD5");
		
		//获取字节数组
		byte[] resource  = "123".getBytes();
		
		//得到加密后的字节数组
		byte[] result = md5.digest(resource);
		
		//转化为16进制32位的字符串
		System.out.println(getHexString(result));
	}
	
	static String getHexString(byte[] b){
		StringBuilder sb = new StringBuilder();
		for(int i= 0; i<b.length;i++){
			 sb.append( HEX_DIG[b[i]& 0xf0 >>>4]);
			 sb.append( HEX_DIG[b[i]& 0x0f]);
		}
		return sb.toString();
	}

密码和一段字符串相加进行编码可增加破解的难度：

	private static final String key = "282328392839283928";
	
	public static String md5(String password){
		try {
			MessageDigest md = MessageDigest.getInstance("md5");
			//密码和字符串相加增加破解的难度
			byte md5[] = md.digest((key+password).getBytes());	
			//进行BASE64编码
			BASE64Encoder  base64 = new BASE64Encoder();
			//明文字符串
			return base64.encode(md5); 
		} catch (NoSuchAlgorithmException e) {
			throw new RuntimeException(e);
		}
	}