java BASE64 encoding and decoding

    /*** 
         * encode by Base64 
         */  
        public static String encodeBase64(byte[] input) throws Exception {  
            Class clazz = Class  
                    .forName("com.sun.org.apache.xerces.internal.impl.dv.util.Base64");  
            Method mainMethod = clazz.getMethod("encode", byte[].class);  
            mainMethod.setAccessible(true);  
            Object retObj = mainMethod.invoke(null, new Object[] { input });  
            return (String) retObj;  
        }  
      
        /*** 
         * decode by Base64 
         */  
        public static byte[] decodeBase64(String input) throws Exception {  
            Class clazz = Class  
                    .forName("com.sun.org.apache.xerces.internal.impl.dv.util.Base64");  
            Method mainMethod = clazz.getMethod("decode", String.class);  
            mainMethod.setAccessible(true);  
            Object retObj = mainMethod.invoke(null, input);  
            return (byte[]) retObj;  
        }