正则表达式（一）

用最普通的方法来解析字符串：

import java.text.MessageFormat;

public class ParseIP2 {
 
 public static void main(String[] args) {
  String text = "192.168.10.5[port=21,type=FTP]";
  parseAddr(text);
  String text2 = "192.168.10.5[port=80]";
  parseAddr(text2);
 }
 
 public static void parseAddr(String text) {
  int leftBraceIndex = text.indexOf('[');
  String ipAddr = text.substring(0, leftBraceIndex);
  String subStr = text.substring(leftBraceIndex+1, text.length()-1);
  String[] strings = subStr.split(",");
  String portString = strings[0];
  String port = portString.split("=")[1];
  String type="HTTP";
  
  if (strings.length == 2) {
   String typeString = strings[1];
   type = typeString.split("=")[1];
  }
  
  String msg = MessageFormat.format("IP地址为{0}的服务器为{1}端口提供的服务为{2}",new Object[] {ipAddr, port, type});
  System.out.println(msg);
 }
}

 

判断一个字符串是否是email地址：

public class ParseEmail {
 
 public static void main(String[] args) {
  String text = " [email protected] ";
  String text1 = "dskfakj";
  String text2 = "@126.com";
  System.out.println(validateEmail(text));
  System.out.println(validateEmail(text1));
  System.out.println(validateEmail(text2));
 }
 
 public static boolean validateEmail(String text) {
  int atIndex = text.indexOf( '@' );
  int dotLastIndex = text.lastIndexOf('.');
  
  //必须含有@和.
  if(atIndex<0 || dotLastIndex<0) {
   return false;
  }
  
  int textLen = text.length();
  
  //不能以@或者.开始或结束
  if(atIndex==0 || atIndex==textLen || dotLastIndex==0 || dotLastIndex==textLen) {
   return false;
  }
  
  //@要在最后一个.之前
  if(atIndex>dotLastIndex) {
   return false;
  }
  return true;
 }
}

 

正 则表达式的应用：

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

public class ExpReg {
 public static void main(String[] args) {
  /*
  Pattern p = Pattern.compile("b*g");
  Matcher m = p.matcher("bbbbbbg");
  boolean b = m.matches();
  System.out.println(b);
  */
  
  boolean b = Pattern.matches("b*g","bug");
  System.out.println(b);
  
  //从文件路径中提取出文件名（包含后缀)
  String regEx = ".+/(.+)$";
  String str="c:/dir1/dir2/name.txt";
  Pattern p = Pattern.compile(regEx);
  Matcher m = p.matcher(str);
  
  if(!m.find()) {
   System.out.println("文件路径格式错误");
   return;
  }
  
  System.out.println(m.group(1));
  
  //判断字符串是否为正确的邮政编码
  System.out.println(Pattern.matches("[0-9]{6}","330215"));
  System.out.println(Pattern.matches("[0-9]{6}","33015"));
  
  //判断字符串是否为正确的国内电话号码
  System.out.println(Pattern.matches("[0-9]{3,4}\\-?[0-9]+","010-95555"));
  System.out.println(Pattern.matches("[0-9]{3,4}\\-?[0-9]+","01095555"));
  System.out.println(Pattern.matches("[0-9]{3,4}\\-?[0-9]+","95555"));
  System.out.println(Pattern.matches("[0-9]{3,4}\\-?[0-9]+","0755-95555"));
  System.out.println(Pattern.matches("[0-9]{3,4}\\-?[0-9]+"," [email protected] "));
 }
}

 

正在学习中。。。。