Java正则表达式实战教学指南

String text = "联系我：user@example.com 或 admin@test.org";
Pattern pattern = Pattern.compile("\\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,}\\b");
Matcher matcher = pattern.matcher(text);
while (matcher.find()) {
    System.out.println("找到邮箱: " + matcher.group());
}

String log = "ERROR: 登录失败\n时间: 2024-05-10 10:00\n用户: alice";
Pattern pattern = Pattern.compile("ERROR:(.*?)时间:(.*?)\\n用户:(\\w+)", Pattern.DOTALL);
Matcher matcher = pattern.matcher(log);
if (matcher.find()) {
    System.out.println("错误详情: " + matcher.group(1).trim());
    System.out.println("用户: " + matcher.group(3));
}

// 匹配日期格式：2024年05月10日
Pattern datePattern = Pattern.compile(
    "(\\d{4})年(\\d{2})月(\\d{2})日", 
    Pattern.UNICODE_CHARACTER_CLASS
);
Matcher m = datePattern.matcher("今天是2024年05月10日");
if (m.find()) {
    String year = m.group(1); // 年
    String month = m.group(2); // 月
    String day = m.group(3); // 日
    System.out.println(year + "-" + month + "-" + day);
}

private static final Pattern URL_PATTERN = 
    Pattern.compile("https?://[\\w.-]+(?:/[\\w./?%&=-]*)?");