java正则表达式

例子

package intro.regex;

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

public class RegexTest {

    public static void main(String [] args){
        Pattern pattern = Pattern.compile("a.*string");
        Matcher matcher = pattern.matcher("a string");

        boolean didMatch = matcher.matches();
        System.out.println(didMatch); //true

        int patternStartIndex = matcher.start(); //0
        int patternEndIndex = matcher.end(); //8
        System.out.println("Start:" + patternStartIndex + " end: " + patternEndIndex);

        matcher = pattern.matcher("a string with more than just the pattern");
        didMatch = matcher.matches();
        System.out.println(didMatch); //false
        matcher = pattern.matcher("a string with more than just the pattern");
        didMatch = matcher.lookingAt();
        System.out.println(didMatch); //true

        pattern = Pattern.compile("[A-Z][a-z]*([A-Z][a-z]*)+");
        matcher = pattern.matcher("Here is a WikiWord followed by AnotherWikiWord, then YetAnotherWikiWord.");
        while(matcher.find()){
            System.out.println("Found whit wiki word: " + matcher.group());
            //Found whit wiki word: WikiWord
      //Found whit wiki word: AnotherWikiWord
          //Found whit wiki word: YetAnotherWikiWord
        }

        System.out.println("*******************************************************");
        matcher.reset();
        StringBuffer buffer = new StringBuffer();
        while(matcher.find()){
            matcher.appendReplacement(buffer, "blah$0blah");
            System.out.println(buffer.toString());
        //Here is a blahWikiWordblah
          //Here is a blahWikiWordblah followed by blahAnotherWikiWordblah
           //Here is a blahWikiWordblah followed by blahAnotherWikiWordblah, then blahYetAnotherWikiWordblah
        }
        matcher.appendTail(buffer);
        System.out.println(buffer.toString());
        //Here is a blahWikiWordblah followed by blahAnotherWikiWordblah, then blahYetAnotherWikiWordblah.
        System.out.println("*******************************************************");

    }
}

几个要点：

1. Matcher.end()方法获得匹配到的子字符串的最后一个字符在字符串中的索引位置+1.

2. lookingAt()方法是从第一个字符看是不是有匹配的字符串，即使有匹配的，但不是从第一个字符开始，也不能匹配成功，如：

Pattern pattern = Pattern.compile("a.*string");
Matcher matcher = pattern.matcher("a string");

matcher = pattern.matcher("a string with more than just the pattern");
boolean didMatch = matcher.matches();
System.out.println(didMatch); //false
matcher = pattern.matcher("a string with more than just the pattern");
didMatch = matcher.lookingAt();
System.out.println(didMatch); //true
matcher = pattern.matcher("Here is a string with more than just the pattern");
didMatch = matcher.lookingAt();
System.out.println(didMatch); //false