如何在java中使用正则表达式替换特定子字符串

Question

我有如下所示的字符串

   when 
   $Event:com.abc.Event(description == "abc")
   then
   logger.info("description"); 

我需要用下面的字符串替换上面的字符串

   when
   $Event:com.abc.Event(description == "abc") from entry-point "EventStream"
   then
   logger.info("description"); 

同样的方式当我遇到

when
$Alarm:com.abc.Alarm(description == "abc")
then
logger.info("alarm description");

我需要更改如下

when
$Alarm:com.abc.Alarm(description == "abc") from entry-point "AlarmStream"
then
logger.info("alarm description");

我想用贪婪匹配的正则表达式替换字符串。请给我一些指点，以达到同样的效果。

Answer 1

简单的解决方案不用担心正则表达式，而是使用Strings方法包含。创建一个Scanner对象，逐行解析字符串行，并将结果添加到字符串缓冲区。

if(line.contains("$Event:com.abc.Event(description == "abc")"){
  sb.append(line + "from entry-point \"EventStream\" ");
} else if(line.contains("$Alarm:com.abc.Alarm(description == \"abc\")") {
 sb.append(line + "from entry-point \"AlarmStream\" ");
}else {
 sb.append(line);
}

Answer 2

将使用正则表达式和测试类的新答案。

import java.util.Scanner;


public class RegEx {

public static void main(String[] args) {
    String text = "when\n$Alarm:com.abc.Alarm(description == \"abc\")\nthen\nlogger.info(\"alarm description\")";
    System.out.println(text);
    StringBuilder sb = new StringBuilder();
    Scanner scan = new Scanner(text);
    while(scan.hasNextLine()){
        String line = scan.nextLine();
        if(line.matches(".*\\.Alarm(.*).*")){
            line+=" from entry-point \"AlarmStream\"";
        }
        sb.append(line+System.getProperty("line.separator"));
    }
    System.out.println(); // Nicer output
    System.out.println(sb.toString());
}

}

输出

when

$Alarm:com.abc.Alarm(description == "abc")

然后

Logger.info(“告警描述”)

什么时候

来自入口点"AlarmStream“的$Alarm:com.abc.Alarm(description ==”abc“)

然后

Logger.info(“告警描述”)