java - 在replaceAll中以编程方式获取捕获组

Question

我想用解析后的 $1 替换字符串中出现的每个正则表达式。我怎样才能做到这一点？

    String line = "foo <<VAR>> bar <<VAR>>";
    Matcher matcher = Pattern.compile("<<(\\w*?)>>").matcher(line);
    Map<String,String> replacements = Collections.singletonMap("VAR","REPLACEMENT");
    String replacedLine = matcher.replaceAll(replacements.get(?.group(1)));
    Assert.assertTrue("foo REPLACEMENT bar REPLACEMENT".equals(replacedLine));

Answer 1

您可以使用Matcher#appendReplacement构建结果“as you match”的方法:

String line = "foo <<VAR>> bar <<VAR>> in <<NO>>";
Matcher m = Pattern.compile("<<(\\w+)>>").matcher(line);
Map<String,String> replacements = Collections.singletonMap("VAR","REPLACEMENT");
StringBuffer replacedLine = new StringBuffer();
while (m.find()) {
    if (replacements.get(m.group(1)) != null)
        m.appendReplacement(replacedLine, replacements.get(m.group(1)));
    else
        m.appendReplacement(replacedLine, m.group());
}
m.appendTail(replacedLine);
System.out.println(replacedLine.toString()); // => foo REPLACEMENT bar REPLACEMENT in <<NO>>

请参阅Java demo .