不解

public class Test04 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        //String str = "欢迎大家访问http://www.xiaojiang.cn了解、参观公司";
        //String str = "网址：www.baidu.com";
        String str = "网址：www.nwsuaf.edu.cn";
        //String regex = "(http://)?www[.]\w+56{1}\p{Alpha}+";
        String regex = "(http://|www)56?\w+56{1}\w+56{1}\p{Alpha}+";
        System.out.println("原字符串是:" + str + "替换后是：");
        str = str.replaceAll(regex, "***");
        System.out.println(str);
        String money = "89,235,678￥";
        System.out.println(money + "转化成数字:");
        String s = money.replaceAll("[,\p{Sc}]" ,"");//"\p{Sc}"可匹配任何货币符号
        long number = Long.parseLong(s);
        System.out.println(number);
    }

}

运行结果如下所示：

我认为上述的正则表达式无法匹配到字符串"www.baidu.com"但是它确实可以匹配到，这是什么原因不理解。

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Test10 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Pattern p;
        Matcher m;
        String regex = "(http://|www)56?\w+56{1}\w+56{1}\p{Alpha}+";
        p = Pattern.compile(regex);
        String s = "新浪:www.sina.cn,央视:http://www.cctv.com,西农:www.nwsuaf.edu.cn,无:www.edu.cn,百度：www.baidu.com";
        System.out.println("原字符串是:" + s);
        m = p.matcher(s);
        while(m.find())
        {
            String str = m.group();
            System.out.println(str);
        }
        System.out.println("剔除字符串中的网站网址后得到的字符串：");
        String result = m.replaceAll("");
        System.out.println(result);
        
    }

}

运行结果