正则表达式--替换空格

题目描述 
请实现一个函数，将一个字符串中的空格替换成“%20”。例如，当字符串为We Are Happy.则经过替换之后的字符串为We%20Are%20Happy。 

import java.util.Scanner; 
import java.util.regex.*; 
public class Solution { 
public String replaceSpace(StringBuffer str) { 
Matcher matcher = Pattern.compile(“\s”).matcher(str); 
return matcher.replaceAll(“%20”); 
} 
public static void main(String[] args) { 
// TODO Auto-generated method stub 
Solution func = new Solution(); 
Scanner scanner = new Scanner(System.in); 
String str =scanner .nextLine(); 
StringBuffer str1 = new StringBuffer(str); 
System.out.println(func.replaceSpace(str1)); 
scanner.close(); 
}

}