Java正则表达式

1、简单认识正则表达式的概念

p( "abc".matches( "...")); //'.'代表字符
    p( "a8729a".replaceAll( "\\d", "-"));//  '\d'代表数字, 由于java中‘\’的转义，所以需要2个‘\’
    Pattern p = Pattern.compile( "[a-z]{3}");//匹配a和z之间的3个字符， 先编译后效率更高
    Matcher m = p.matcher( "fgh");
    p(m.matches());
    p( "fgha".matches( "[a-z]{3}"));

2、初步认识. * + ?

.：匹配1个字符

*：匹配任意次

+：匹配至少1次

?: 匹配0或1次

p( "a".matches( "."));
    p( "aa".matches( "aa"));
    p( "aaaa".matches( "a*"));
    p( "aaaa".matches( "a+"));
    p( "".matches("a*"));
    p( "aaaa".matches( "a?")); //false
    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]")); //[]代表范围

3、范围

p( "a".matches( "[abc]"));//取abc3个字符中的某一个
    p( "a".matches( "[^abc]"));//false，取除了abc之外的字符
    p( "A".matches( "[a-zA-Z]"));
    p( "A".matches( "[a-z]|[A-Z]"));和上面的【a-zA-Z】一样
    p( "A".matches( "[a-z[A-Z]]"));和上面的【a-zA-Z】一样
    p( "R".matches( "[A-Z&&[RFG]]"));  &&代表并且

4、认识\s \w \d \

p( " \n\r\t".matches( "\\s{4}"));
    p( " ".matches( "\\S")); //false
    p( "a_8".matches( "\\w{3}"));
    p( "abc888&^%".matches( "[a-z]{1,3}\\d+[&^#%]+"));
    p( "\\".matches("\\\\"));

5、

//POSIX Style
     p( "a".matches( "\\p{Lower}"));
        
         //boundary
        p( "hello sir".matches( "^h.*")); // 注意： ^在中括号里面代表取反，在中括号外面代表以什么为开头
        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( "[email protected]".matches( "[\\w[.-]]+@[\\w[.-]]+\\.[\\w]+"));