这里面包含了一百多个JAVA源文件

				For more information on a MAC, see RFC 2104. See also e467 Listing All Available Message Authentication Code (MAC) Key Generators. 
				    try {
				        // Generate a key for the HMAC-MD5 keyed-hashing algorithm
				        KeyGenerator keyGen = KeyGenerator.getInstance("HmacMD5");
				        SecretKey key = keyGen.generateKey();
				    
				        // Generate a key for the HMAC-SHA1 keyed-hashing algorithm
				        keyGen = KeyGenerator.getInstance("HmacSHA1");
				        key = keyGen.generateKey();
				    } catch (java.security.NoSuchAlgorithmException e) {
				    }