Java:用已处理的匹配替换regexp

Question

假设我有以下字符串:

String in = "A xx1 B xx2 C xx3 D";

我想要结果:

String out = "A 1 B 4 C 9 D";

我想以类似的方式做到这一点:

String out = in.replaceAll(in, "xx\\d",
    new StringProcessor(){
        public String process(String match){ 
            int num = Integer.parseInt(match.replaceAll("x",""));
            return ""+(num*num);
        }
    } 
);

也就是说,使用字符串处理器在执行实际替换之前修改匹配的子字符串.

是否已经编写了一些库来实现这一目标？

Answer 1

用途Matcher.appendReplacement():

    String in = "A xx1 B xx2 C xx3 D";
    Matcher matcher = Pattern.compile("xx(\\d)").matcher(in);
    StringBuffer out = new StringBuffer();
    while (matcher.find()) {
        int num = Integer.parseInt(matcher.group(1));
        matcher.appendReplacement(out, Integer.toString(num*num));
    }
    System.out.println(matcher.appendTail(out).toString());