java - 仅在尚未转义时才转义反斜杠

Question

非常简单的测试:

String value = "Test escape single backslash C:\\Dir  [Should not escape \\\\characters here\\\\]";
String result = value.replaceAll(Pattern.quote("\\"), Matcher.quoteReplacement("\\\\"));
System.out.println(value);
System.out.println(result);

我得到了输出:

Test escape single backslash C:\Dir  [Should not escape \\characters here\\]
Test escape single backslash C:\\Dir  [Should not escape \\\\characters here\\\\]

将表达式更改为:

"(?<![\\\\])"+Pattern.quote("\\")

如

String result = value.replaceAll("(?<![\\\\])"+Pattern.quote("\\"), Matcher.quoteReplacement("\\\\"));

给我:

Test escape single backslash C:\Dir  [Should not escape \\characters here\\]
Test escape single backslash C:\\Dir  [Should not escape \\\characters here\\\]

这很接近，但没有雪茄。

我错过了什么？

预期输出:

Test escape single backslash C:\\Dir  [Should not escape \\characters here\\]

Answer 1

怎么样

String result = value.replaceAll("\\\\{1,2}",  Matcher.quoteReplacement("\\\\"));

想法是让匹配器使用两个 \ 字面量并且不更改它们(用它们自己替换它们 Matcher.quoteReplacement("\\\\"))但是如果只找到一个 \ 文字也将其替换为两个 \ \ (与第一种情况相同的替换)。

有点像

\\\
^^  - replace with `\\`
  ^ - also replace with `\\`