JAVA RegularExpressions

JAVA RegularExpressions

JAVA RegularExpressions 流行于unix
幽默 豁达的女生可遇而不可求
用途：匹配 查找 替换
for instance：IP地址是否正确，从网页爬出email url
下载网页：不仅可以下载当前网页 而且可以下载当前网页中的链接

java.lang.String
java.util.regex.Pattern
java.util.regex.Matcher

替代StringTonkier

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


public class Test {

	public static void main(String[] args) {
		//����ʶ������ʽ�ĸ���
		
		p("abc".matches("..."));
		p("a8729a".replaceAll("\\d", "-"));
		Pattern p = Pattern.compile("[a-z]{3}");
		Matcher m = p.matcher("fgh");
		p(m.matches());
		p("fgha".matches("[a-z]{3}"));
		
		
		//������ʶ. * + ?
		
		p("a".matches("."));
		p("aa".matches("aa"));
		p("aaaa".matches("a*"));
		p("aaaa".matches("a+"));
		p("".matches("a*"));
		p("aaaa".matches("a?"));
		p("".matches("a?"));
		p("a".matches("a?"));
		p("214523145234532".matches("\\d{3,100}"));
		p("192.168.0.aaa".matches("\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}"));
		p("192".matches("[0-2][0-9][0-9]"));
		
		
		//��Χ
		
		p("a".matches("[abc]"));
		p("a".matches("[^abc]"));
		p("A".matches("[a-zA-Z]"));
		p("A".matches("[a-z]|[A-Z]"));
		p("A".matches("[a-z[A-Z]]"));
		p("R".matches("[A-Z&&[RFG]]"));
		
		
		//��ʶ\s \w \d \
		
		p(" \n\r\t".matches("\\s{4}"));
		p(" ".matches("\\S"));
		p("a_8".matches("\\w{3}"));
		p("abc888&^%".matches("[a-z]{1,3}\\d+[&^#%]+"));
		p("\\".matches("\\\\"));
		
		
		//POSIX Style
		//p("a".matches("\\p{Lower}"));
		
		//boundary
		
		p("hello sir".matches("^h.*"));
		p("hello sir".matches(".*ir$"));
		p("hello sir".matches("^h[a-z]{1,3}o\\b.*"));
		p("hellosir".matches("^h[a-z]{1,3}o\\b.*"));
		//whilte lines
		p(" \n".matches("^[\\s&&[^\\n]]*\\n$"));
				
		p("aaa 8888c".matches(".*\\d{4}."));
		p("aaa 8888c".matches(".*\\b\\d{4}."));
		p("aaa8888c".matches(".*\\d{4}."));
		p("aaa8888c".matches(".*\\b\\d{4}."));
		
		
		//email
		//p("[e-mail]".matches("[\\w[.-]]+@[\\w[.-]]+\\.[\\w]+"));
		
		//matches find lookingAt
		
		Pattern p = Pattern.compile("\\d{3,5}");
		String s = "123-34345-234-00";
		Matcher m = p.matcher(s);
		p(m.matches());
		m.reset();
		p(m.find());
		p(m.start() + "-" + m.end());
		p(m.find());
		p(m.start() + "-" + m.end());
		p(m.find());
		p(m.start() + "-" + m.end());
		p(m.find());
		//p(m.start() + "-" + m.end());
		p(m.lookingAt());
		p(m.lookingAt());
		p(m.lookingAt());
		p(m.lookingAt());
		
		
		//replacement
		
		Pattern p = Pattern.compile("java", Pattern.CASE_INSENSITIVE);
		Matcher m = p.matcher("java Java JAVa JaVa IloveJAVA you hateJava afasdfasdf");
		StringBuffer buf = new StringBuffer();
		int i=0;
		while(m.find()) {
			i++;
			if(i%2 == 0) {
				m.appendReplacement(buf, "java");
			} else {
				m.appendReplacement(buf, "JAVA");
			}
		}
		m.appendTail(buf);
		p(buf);
		
		
		//group
		
		Pattern p = Pattern.compile("(\\d{3,5})([a-z]{2})");
		String s = "123aa-34345bb-234cc-00";
		Matcher m = p.matcher(s);
		while(m.find()) {
			p(m.group());
		}
		
		
		//qulifiers
		
		Pattern p = Pattern.compile(".{3,10}+[0-9]");
		String s = "aaaa5bbbb68";
		Matcher m = p.matcher(s);
		if(m.find())
			p(m.start() + "-" + m.end());
		else 
			p("not match!");
		
		
		//non-capturing groups
		
		Pattern p = Pattern.compile(".{3}(?=a)");
		String s = "444a66b";
		Matcher m = p.matcher(s);
		while(m.find()) {
			p(m.group());
		}
		
		
		//back refenrences
		
		Pattern p = Pattern.compile("(\\d(\\d))\\2");
		String s = "122";
		Matcher m = p.matcher(s);
		p(m.matches());
		
		
		//flags�ļ�д
		//Pattern p = Pattern.compile("java", Pattern.CASE_INSENSITIVE);
		p("Java".matches("(?i)(java)"));
	}
	
	public static void p(Object o) {
		System.out.println(o);
	}

}