英文句子反转，单词不反转

关于一道面试题：如何让英文句子反转，单词不反转 (且最小的空间复杂度）

package com.morganinc.wiki;
 
import org.apache.commons.lang.StringUtils;
 
/**
 * Created by liaowenyue on 2017/5/22.
 */
public class SentenceReverse {
    public static String reverseSentence(String src) {
 
        if (StringUtils.isBlank(src)) {
            return "";
        }
 
        String[] wordArray = src.split(" ");
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < wordArray.length; i++) {
            if (StringUtils.isNotBlank(wordArray[wordArray.length - i - 1])) {
                sb.append(wordArray[wordArray.length - i - 1]).append(" ");
            }
        }
        return sb.toString();
    }
 
    public static void main(String[] args) {
        System.out.println(SentenceReverse.reverseSentence("much.    very you love I"));
    }
}