===== replaceAll, replace =====
<WRAP left notice 80%>
  * description : 정규표현식을 사용한 replaceall 활용 연구
  * author      : 주레피
  * email       : dhan@repia.com
  * lastupdate  : 2020-04-14
</WRAP>
<WRAP clear/>

===== Case study =====
1. 이미지 소스의 base64문자열 제거 (<img src="data-image/png;base64, ......."/> -> <img src=""/>)
<code java>
String testStr="<img src=\"data:image/png;base64,iVBORw0KGgo ... 5XTk8evT\">";
System.out.println(testStr.replaceAll("src=\"data:image[^\"]*\"", "src=\"\""));
</code>
\\
2. http://www.repia.com -> <a href="http://www.repia.com" target="blank">www.repia.com</a>(링크추가) \\
<code java>
String testStr="http://www.repia.com ";
System.out.println(testStr.replaceAll("(http(s)?://([^ ]*))", "<a href=\"$1\" target=\"blank\">$3</a>"));
</code>
> 괄호 순서대로 \\ (http(s)?:%%//%%([^ ]*)) => $1 \\ (s) => $2 \\ ([^ ]*) => $3
<code java>
// Source
public static void main(String[] args)
{
    String[] linkHostList = { "http://www.sit.re.kr/kr/board/result/boardView.do?bbsIdx="
                            , "https://scienceon.kisti.re.kr/srch/selectPORSrchTrend.do?cn="
                            , "https://www.kosen21.org/info/kosenReport/reportView.do?articleSeq=" };

    for(String linkHost: linkHostList) {
        System.out.printf("%s -> %s\n", linkHost, linkHost.replaceAll("(http(s)?://([^/]*)(/.*))", "$3"));
    }
}
// Output <= $3
http://www.sit.re.kr/kr/board/result/boardView.do?bbsIdx= -> www.sit.re.kr
https://scienceon.kisti.re.kr/srch/selectPORSrchTrend.do?cn= -> scienceon.kisti.re.kr
https://www.kosen21.org/info/kosenReport/reportView.do?articleSeq= -> www.kosen21.org

// Output <= $1
http://www.sit.re.kr/kr/board/result/boardView.do?bbsIdx= -> http://www.sit.re.kr/kr/board/result/boardView.do?bbsIdx=
https://scienceon.kisti.re.kr/srch/selectPORSrchTrend.do?cn= -> https://scienceon.kisti.re.kr/srch/selectPORSrchTrend.do?cn=
https://www.kosen21.org/info/kosenReport/reportView.do?articleSeq= -> https://www.kosen21.org/info/kosenReport/reportView.do?articleSeq=

// Output <= $2
http://www.sit.re.kr/kr/board/result/boardView.do?bbsIdx= -> 
https://scienceon.kisti.re.kr/srch/selectPORSrchTrend.do?cn= -> s
https://www.kosen21.org/info/kosenReport/reportView.do?articleSeq= -> s

// Output <= $4
http://www.sit.re.kr/kr/board/result/boardView.do?bbsIdx= -> /kr/board/result/boardView.do?bbsIdx=
https://scienceon.kisti.re.kr/srch/selectPORSrchTrend.do?cn= -> /srch/selectPORSrchTrend.do?cn=
https://www.kosen21.org/info/kosenReport/reportView.do?articleSeq= -> /info/kosenReport/reportView.do?articleSeq=

</code>

\\
3. 한줄로 간단하게 ltrim, rtrim
<code java>
String testStr=str.replaceAll("^\\s+",, ""); //ltrim
String testStr=str.replaceAll("\\s+$",, ""); //rtrim
</code>
> '^' mean 처음부터 매칭 \\ '$' mean 라인마지막 매칭 \\ %%\\%%s+ mean white space 
\\
4. 특수 기호 사용하기  \\
4.1 []로 싸주면 문자자체를 인식하는 것
<code java>
* => [*]
+ => [+]
$ => [$]
| => [|]
? => [?]
</code>
4.2 \\를 붙여줘야 하는 것
<code java>
( -> \\(
) -> \\)
{ -> \\{
} -> \\}
^ -> \\^
[ -> \\[
] -> \\]
</code>
4.3 나머지 기호 !#%&@':;-.<>,~` 는 괜찮은 것 같다. \\
<code java>
String c = "?$(){}*+^|[]";
c = c.replaceAll("[?][$]\\(\\)\\{\\}[*][+]\\^[|]\\[\\]", "");
</code>



===== Ref =====
  * [[https://docs.oracle.com/javase/8/docs/api/java/util/regex/Pattern.html|Pattern, Regular Experssion]]
  * [[https://regexr.com/|Regular 온라인 Test]]
  * [[http://coolx.net/cboard/develop/446|replaceAll에서 정규표현식 특수문자 취급 자바]]

===== Tip =====

===== Troubleshooting =====

{{tag>주레피 replaceAll replace}}