java 正则

1. matches() 匹配全部

Pattern p = Pattern.compile("reg");

Matcher m = p.matcher("String");

System.out.println(m.matches());

2:(matches 和find不要一起用,用reset()吐出来) 

　find()匹配部分

while(m.find()){

　　SYstem.out.println(m.group());//group() 每次循环 find()匹配到的部分

}

  replaceAll() 替代匹配的所有

     System.out.println(m.replaceAll("java"));

  比replaceAll()更灵活的替换appendReplacement(StringBuffer sb,String yourString);

  //把偶数index的java 替换为"猫叔";

    StringBuffer sb = new StringBuffer();
    int i=0;
    while(m.find()){
    i++;
    if(i%2==0){
    m.appendReplacement(sb, "猫叔");
    }
    }
    m.appendTail(sb);
    System.out.println(sb);

3.更强大的分组()()式

/*Pattern p2 = Pattern.compile("([\\w[-._.]]+)(@[\\w[\\d]]+\\.[\\w]+)");
Matcher m2 =p2.matcher("-newobj_1@163.com,newobj@163.com,1299291758@qq.com");
while(m2.find()){
System.out.println(m2.group(1));
}*/

4.实际应用(爬email)

...所有以上的内容如下:

package first;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class T1 {

/**
* @param args
*/
public static void main(String[] args) {
//认识\s：space, \w: [a-zA-Z_0-9] , \d:[0-9]
//System.out.println(" \r\n\t".matches("\\s{4}"));
//System.out.println("hello sir".matches(".*sir$"));
//System.out.println("newobj@163.com".matches("[\\w[_.]]+@[\\w[_.]]+\\.[\\w[_.]]+"));

/*Pattern p = Pattern.compile("[\\d]{3,5}");
String tt = "123-2345-33333-00-12";
Matcher m = p.matcher(tt);
System.out.println(m.matches());
m.reset();
System.out.println(m.find());
System.out.println(m.find());
System.out.println(m.find());
System.out.println(m.find());*/

//看group(当前匹配的结果)以及repalceAll;
Pattern p = Pattern.compile("java",Pattern.CASE_INSENSITIVE);
String a = "I lova java ,he heats Java, hanmeimei love JAva too , and you about java ?";
Matcher m = p.matcher(a);
// while(m.find()){
// System.out.println(m.group());
// }
//System.out.println(m.replaceAll("java"));

//把偶数index的java 替换为"猫叔";
/*StringBuffer sb = new StringBuffer();
int i=0;
while(m.find()){
i++;
if(i%2==0){
m.appendReplacement(sb, "猫叔");
}
}
m.appendTail(sb);
System.out.println(sb);*/

//看看更强大的group
/*Pattern p2 = Pattern.compile("([\\w[-._.]]+)(@[\\w[\\d]]+\\.[\\w]+)");
Matcher m2 =p2.matcher("-newobj_1@163.com,newobj@163.com,1299291758@qq.com");
while(m2.find()){
System.out.println(m2.group(1));
}*/
//爬email
BufferedReader bfr = null;
try{
bfr = new BufferedReader(new FileReader(new File("D:/大家留下email吧.htm")));
String line ="";
String myemail = "newobj@163.com";
Pattern pemail = Pattern.compile("[\\w_-]+@[\\w\\d]+\\.[\\w]+");
Matcher meail = null;
//meail = pemail.matcher(myemail);
//System.out.println(meail.matches());
while((line=bfr.readLine())!=null){
meail = pemail.matcher(line);
while(meail.find()){
System.out.println(meail.group());
}
}
}catch (Exception e) {
e.printStackTrace();
}finally{
try {
bfr.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}

}

原文：http://www.cnblogs.com/yanjunwu/p/3764067.html