java - 正则表达式从多行匹配到字符串缓冲区末尾并替换为 ""

Question

我有以下文件内容，我正在尝试匹配下面解释的注册表，并将匹配的开头(“On....write”)替换为空白“”到字符串缓冲区的末尾:

-- file.txt (Before regx match and replace) -- 
test

On blah

more blah wrote:

So, this should be stripped all out and all that left should be the above test contents.
-- EOF -- 


-- file.txt (After regex mach and replace) -- 
test
-- EOF -- 

如果我将文件内容从上面读取到字符串并尝试匹配“On...wrote:”部分，我似乎无法从“On...wrote:”替换到文件末尾: “...:

    // String text = <file contents from above...the Before contents>
    Pattern PATTERN = 
      Pattern.compile("^(On\\s(.+)wrote:)$", Pattern.MULTILINE | Pattern.DOTALL );
    Matcher m = PATTERN.matcher(text);
    if (m.find()) {
       // This matches but I want to strip from "On....wrote:  -> <end of string>
       text = m.replaceAll("");  // This should only contain "test"

    }

Answer 1

不需要做匹配，直接替换即可。如果替换中使用的模式与任何内容都不匹配，那么什么都不会发生。

尝试以下操作:

// String text = <file contents from above...the Before contents>
String text = text.replaceAll("^(On.*?wrote:).*$", "");

注意:您可能需要从正则表达式内部打开 Pattern.MULTILINE 和 Pattern.DOTALL 的标志，您可以这样做像这样:

String text = text.replaceAll("(?sm)^(On.*?wrote:).*$", "");

编辑:当然你可以:

// String text = <file contents from above...the Before contents>
Pattern PATTERN = 
  Pattern.compile("^(On.*?wrote:).*$", Pattern.MULTILINE | Pattern.DOTALL );
Matcher m = PATTERN.matcher(text);
if (m.find()) {
   text = m.replaceAll("");  // This should only contain "test"

}