如何用正则表达式从一个String中提取出英文单词？

[FutureStonesoft]

String中可能含有中文等等任何字符，但是最终提取出来的是英文，
而且要考虑考he's或者low-income这类情况，也就是能吧
he's和low-inome都识别为一个单词，而不是拆分为he s low income四个单词。

比如有一个String如下：
"He's a boy.And she has a low-income.
------ 中国(china)是------He's a student."

提出出来的单词是：
He's
a
boy
And
she
has
a
low-income
china
student

[treeroot]

http://blog.csdn.net/treeroot/archive/2004/11/11/176610.aspx

[stonecsdn]

import java.util.regex.Pattern;
import java.util.regex.Matcher;
public class PickWord{

public static void main(String args[]){
String regex = "([\\w]+(\\'|\\-)*[\\w]+)|([\\w]+)";
Pattern pattern = Pattern.compile(regex, Pattern.CASE_INSENSITIVE);
String article="He's a boy.And she has a low-income.";
Matcher matcher=pattern.matcher(article);
while (matcher.find()) {
System.out.println(matcher.group());
}
}
}