Java使用正则提取字符串中的内容的详细步骤

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

public class RegexExample {
    public static void main(String[] args) {
        String text = "订单号：ABC123，日期：2023-08-20，金额：¥500.00";
        
        // 1. 定义正则表达式
        String regex = "([A-Z]{3}\\d{3})|(\\d{4}-\\d{2}-\\d{2})|(¥\\d+\\.\\d{2})";
        
        // 2. 编译正则表达式
        Pattern pattern = Pattern.compile(regex);
        
        // 3. 创建Matcher对象
        Matcher matcher = pattern.matcher(text);
        
        // 4. 遍历所有匹配项
        while (matcher.find()) {
            // 5. 提取完整匹配内容
            System.out.println("完整匹配: " + matcher.group(0));
            
            // 6. 提取分组内容（如果有分组）
            for (int i=1; i<=matcher.groupCount(); i++) {
                if (matcher.group(i) != null) {
                    System.out.println("分组 " + i + ": " + matcher.group(i));
                }
            }
        }
    }
}

String text = "苹果5个，香蕉3.5公斤";
Pattern pattern = Pattern.compile("\\d+(\\.\\d+)?");
Matcher matcher = pattern.matcher(text);
while (matcher.find()) {
    System.out.println(matcher.group()); // 输出 5, 3.5
}

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

String text = "姓名：张三，年龄：25";
String regex = "姓名：(?<name>\\w+)，年龄：(?<age>\\d+)";
Pattern pattern = Pattern.compile(regex);
Matcher matcher = pattern.matcher(text);
if (matcher.find()) {
    System.out.println(matcher.group("name")); // 张三
    System.out.println(matcher.group("age"));  // 25
}

String text = "<div>内容1</div><div>内容2</div>";
Pattern pattern = Pattern.compile("<div>(.*?)</div>"); // 使用 ? 实现非贪婪匹配
Matcher matcher = pattern.matcher(text);
while (matcher.find()) {
    System.out.println(matcher.group(1)); // 输出 内容1, 内容2
}