Pattern类

java.util.regex

Class Pattern

• java.lang.Object
• • java.util.regex.Pattern

• All Implemented Interfaces:

  Serializable

  ---

  
  

  public final class Pattern
  extends Object
  implements Serializable

  A compiled(编译) representation(表示) of a regular expression(表达).

  A regular expression, specified(指定) as a string, must first be compiled into an instance of this class. The resulting pattern can then be used to create aMatcher object that can match arbitrary(任意的)character sequences against(反对) the regular expression. All of the stateinvolved(涉及) in performing(执行) a matchresides(存在) in the matcher, so many matchers canshare(共享) thesame(相同的) pattern.

  A typical(典型的) invocation(调用) sequenceis thus

   Pattern p = Pattern.compile("a*b");
   Matcher m = p.matcher("aaaaab");
   boolean b = m.matches();

  A matches method is defined(定义) by this class as a convenience(方便) for when a regular expression is usedjust once(仅此一次). This method compiles an expression and matches an input sequence against it in a single invocation(调用). The statement

   boolean b = Pattern.matches("a*b", "aaaaab");

  is equivalent(相等的) to the three statementsabove(上文),though(尽管) forrepeated(重复的) matches it isless efficient(更有效率的)since(因为) it does notallow(允许) the compiled pattern to bereused(重复利用).

  Instances of this class are immutable(不变的) and are safe for use by multipleconcurrent threads(并发线程). Instances of theMatcher class are not safe forsuch use(这种用途).

  
  

  Modifier and Type	Field and Description
  static int	CANON_EQ Enables canonical( 典型) equivalence.
  static int	CASE_INSENSITIVE Enables case-insensitive matching.(不区分大小写)
  static int	COMMENTS Permits whitespace and comments in pattern.(允许空白和注释)
  static int	DOTALL Enables dotall mode.
  static int	LITERAL Enables literal parsing of the pattern.
  static int	MULTILINE Enables multiline mode.(多行模式)
  static int	UNICODE_CASE Enables Unicode-aware case folding.
  static int	UNICODE_CHARACTER_CLASS Enables the Unicode version of Predefined character classes and POSIX character classes.
  static int	UNIX_LINES Enables Unix lines mode.