对文字简单的加密解密

/**
     * 测试byte 
     */
    public void test3(){
        String str = "菲吓鳞";
        byte[] b = new byte[1024];
        b = str.getBytes();
        byte[] fs = new byte[1024];
        for (int i = 0; i < b.length; i++) {
            byte f =  b[i];
            if(f == 255){
                f = 0;
            }else{
                fs[i] += --f;
            }
        }
        System.out.println("加密后：" + new String(fs));
        
        byte[] yb = new byte[1024];
        for (int i = 0; i < fs.length; i++) {
            byte f = fs[i];
            if(f == 0){
                f=(byte) 255;
            }else{
                yb[i] += ++f;
            }
        }
        System.out.println("解密后：" + new String(yb));
    }