A:Pattern和Matcher的概述
    B:模式和匹配器的典型调用顺序

    1. //通过JDK提供的API,查看Pattern类的说明
    2. //典型的调用顺序是
    3. Pattern p = Pattern.compile("a*b");
    4. Matcher m = p.matcher("aaaaab");
    5. boolean b = m.matches();
        public static void demo1() {
            Pattern p = Pattern.compile("a*b");                    //获取到正则表达式
            Matcher m = p.matcher("aaaaab");                    //获取匹配器
            boolean b = m.matches();                            //看是否能匹配,匹配就返回true
    
            System.out.println(b);//true
    
            System.out.println("aaaaab".matches("a*b")); //true         //与上面的结果一样
        }