jackson api로 json 데이터를 java object로 저장하는 방법이 궁금합니다.

Question

안녕하세요 코딩 초보가 jackson api로 json to object 하는 과정에서 문제가 생겨서 글을 올립니다.현재 java, jsp 공부 중이며 jackson을 이용해서 영화진흥원의 박스오피스 api의 json을 이용해(rest형식)영화 제목, 개봉날짜, 영화정보 등을 출럭하는 것이 목표입니다. 영화진흥원 박스오피스 api 링크http://kobis.or.kr/kobisopenapi/homepg/apiservice/searchServiceInfo.do json 응답 링크를 URL 객체로 받아 HttpURLConnection과 BufferedReader를 이용하여 json 파일을 불러올 수 있으며,json 파일을 java object로 받기 위해 http://www.jsonschema2pojo.org/에서 json 데이터를 담을 DTO class를 3개 생성했습니다.1.BoxOffice.classpackage userTest; public class BoxOffice { private BoxOfficeResult boxOfficeResult; private DailyBoxOfficeList dailyBoxOfficeList; public BoxOfficeResult getBoxOfficeResult () { return boxOfficeResult; } public void setBoxOfficeResult (BoxOfficeResult boxOfficeResult) { this.boxOfficeResult &#61; boxOfficeResult; } public DailyBoxOfficeList getdailyBoxOfficeList() { return dailyBoxOfficeList; } public void setDailyBoxOfficeList(DailyBoxOfficeList dailyBoxOfficeList) { this.dailyBoxOfficeList &#61; dailyBoxOfficeList; } &#64;Override public String toString() { return &#34;[boxOfficeResult &#61; &#34;&#43;boxOfficeResult&#43;&#34;]&#34;; } } 2.BoxOfficeResult.classpackage userTest; public class BoxOfficeResult { private DailyBoxOfficeList[] dailyBoxOfficeList; private String boxofficeType; private String showRange; public DailyBoxOfficeList[] getDailyBoxOfficeList () { return dailyBoxOfficeList; } public void setDailyBoxOfficeList (DailyBoxOfficeList[] dailyBoxOfficeList) { this.dailyBoxOfficeList &#61; dailyBoxOfficeList; } public String getBoxofficeType () { return boxofficeType; } public void setBoxofficeType (String boxofficeType) { this.boxofficeType &#61; boxofficeType; } public String getShowRange () { return showRange; } public void setShowRange (String showRange) { this.showRange &#61; showRange; } &#64;Override public String toString() { return &#34;[dailyBoxOfficeList &#61; &#34;&#43;dailyBoxOfficeList&#43;&#34;, boxofficeType &#61; &#34;&#43;boxofficeType&#43;&#34;, showRange &#61; &#34;&#43;showRange&#43;&#34;]&#34;; } } 3.DailyBoxOfficeList.classpackage userTest; public class DailyBoxOfficeList { private String rnum; private String audiCnt; private String salesAcc; private String scrnCnt; private String rankInten; private String salesShare; private String movieNm; private String salesAmt; private String movieCd; private String salesChange; private String audiInten; private String audiChange; private String rankOldAndNew; private String rank; private String openDt; private String salesInten; private String showCnt; private String audiAcc; public String getRnum () { return rnum; } public void setRnum (String rnum) { this.rnum &#61; rnum; } public String getAudiCnt () { return audiCnt; } public void setAudiCnt (String audiCnt) { this.audiCnt &#61; audiCnt; } public String getSalesAcc () { return salesAcc; } public void setSalesAcc (String salesAcc) { this.salesAcc &#61; salesAcc; } public String getScrnCnt () { return scrnCnt; } public void setScrnCnt (String scrnCnt) { this.scrnCnt &#61; scrnCnt; } public String getRankInten () { return rankInten; } public void setRankInten (String rankInten) { this.rankInten &#61; rankInten; } public String getSalesShare () { return salesShare; } public void setSalesShare (String salesShare) { this.salesShare &#61; salesShare; } public String getMovieNm () { return movieNm; } public void setMovieNm (String movieNm) { this.movieNm &#61; movieNm; } public String getSalesAmt () { return salesAmt; } public void setSalesAmt (String salesAmt) { this.salesAmt &#61; salesAmt; } public String getMovieCd () { return movieCd; } public void setMovieCd (String movieCd) { this.movieCd &#61; movieCd; } public String getSalesChange () { return salesChange; } public void setSalesChange (String salesChange) { this.salesChange &#61; salesChange; } public String getAudiInten () { return audiInten; } public void setAudiInten (String audiInten) { this.audiInten &#61; audiInten; } public String getAudiChange () { return audiChange; } public void setAudiChange (String audiChange) { this.audiChange &#61; audiChange; } public String getRankOldAndNew () { return rankOldAndNew; } public void setRankOldAndNew (String rankOldAndNew) { this.rankOldAndNew &#61; rankOldAndNew; } public String getRank () { return rank; } public void setRank (String rank) { this.rank &#61; rank; } public String getOpenDt () { return openDt; } public void setOpenDt (String openDt) { this.openDt &#61; openDt; } public String getSalesInten () { return salesInten; } public void setSalesInten (String salesInten) { this.salesInten &#61; salesInten; } public String getShowCnt () { return showCnt; } public void setShowCnt (String showCnt) { this.showCnt &#61; showCnt; } public String getAudiAcc () { return audiAcc; } public void setAudiAcc (String audiAcc) { this.audiAcc &#61; audiAcc; } &#64;Override public String toString() { return &#34;[rnum &#61; &#34;&#43;rnum&#43;&#34;, audiCnt &#61; &#34;&#43;audiCnt&#43;&#34;, salesAcc &#61; &#34;&#43;salesAcc&#43;&#34;, scrnCnt &#61; &#34;&#43;scrnCnt&#43;&#34;, rankInten &#61; &#34;&#43;rankInten&#43;&#34;, salesShare &#61; &#34;&#43;salesShare&#43;&#34;, movieNm &#61; &#34;&#43;movieNm&#43;&#34;, salesAmt &#61; &#34;&#43;salesAmt&#43;&#34;, movieCd &#61; &#34;&#43;movieCd&#43;&#34;, salesChange &#61; &#34;&#43;salesChange&#43;&#34;, audiInten &#61; &#34;&#43;audiInten&#43;&#34;, audiChange &#61; &#34;&#43;audiChange&#43;&#34;, rankOldAndNew &#61; &#34;&#43;rankOldAndNew&#43;&#34;, rank &#61; &#34;&#43;rank&#43;&#34;, openDt &#61; &#34;&#43;openDt&#43;&#34;, salesInten &#61; &#34;&#43;salesInten&#43;&#34;, showCnt &#61; &#34;&#43;showCnt&#43;&#34;, audiAcc &#61; &#34;&#43;audiAcc&#43;&#34;]&#34;; } } 현제까지 연습해본 코드입니다. json 링크에서 요청한 get값은 targetDt&#61;20200101,itemPerPage&#61;1로 20200101년도 박스오피스 중 하나의 영화정보를 받아옵니다.4. main메소드 실행연습package userTest;import java.io.BufferedReader; import java.io.InputStreamReader; import java.net.HttpURLConnection; import java.net.URL; import java.util.Map;import com.fasterxml.jackson.core.type.TypeReference; import com.fasterxml.jackson.databind.ObjectMapper;public class JsonToObject { public static void main(String[] args) { String urlStr &#61; &#34;http://www.kobis.or.kr/kobisopenapi/webservice/rest/boxoffice/searchDailyBoxOfficeList.json&#34; &#43; &#34;?key&#61;430156241533f1d058c603178cc3ca0e&targetDt&#61;20200101&itemPerPage&#61;1&#34;; BoxOffice boxOffice &#61; null; BoxOfficeResult bresult &#61; null; DailyBoxOfficeList dlist&#61;null ; BufferedReader br &#61; null; try { URL url &#61; new URL(urlStr); HttpURLConnection urlconnection &#61;(HttpURLConnection) url.openConnection(); urlconnection.setRequestMethod(&#34;GET&#34;); br &#61; new BufferedReader(new InputStreamReader(urlconnection.getInputStream(),&#34;utf-8&#34;)); String result&#61;&#34;&#34;; String line; while((line &#61; br.readLine())!&#61; null) { result &#43;&#61;line&#43;&#34;
&#34;; } ObjectMapper mapper &#61; new ObjectMapper(); boxOffice &#61;mapper.readValue(result, BoxOffice.class); System.out.println(&#34;1 :&#34;&#43;result); System.out.println(&#34;2 :&#34;&#43;boxOffice.getBoxOfficeResult()); System.out.println(&#34;3 :&#34;&#43;boxOffice.getBoxOfficeResult().getBoxofficeType()); System.out.println(&#34;4 :&#34;&#43;boxOffice.getBoxOfficeResult().getShowRange()); System.out.println(&#34;5 :&#34;&#43;boxOffice.getBoxOfficeResult().getDailyBoxOfficeList()); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } } 5. 실행 결과 box타입의 변수로 mapper.readValue를 사용해서 BoxofficeType, ShowRange 까지는 출력이 가능한데DailyBoxOfficeList의 배열 값(형광색)을 출력하지 못하고 있습니다.BoxOfficeResult 타입의 변수로 readValue()를 하면 DailyBoxOfficeList 주소값이 나오고DailyBoxOfficeList를 이용하면 null값이 나옵니다.사이트를 돌아봤지만 경험부족과 영어미숙으로 아직도 답을 못찾고 있습니다.jackson 숙련자분들의 명쾌한 답변을 부탁드립니다. 읽어주셔서 감사합니다.

swp0419 · Accepted Answer

DailyBoxOfficeList 는 배열이니까 주소값이 나오는게 당연한거 같은데..배열을 받아서 for문으로 돌리면 되는거 아닌가요?DailyBoxOfficeList[] list &#61; boxOffice.getBoxOfficeResult().getDailyBoxOfficeList(); for(DailyBoxOfficeList dailyBoxOfficeList : list) { System.out.println(dailyBoxOfficeList); }

plantG · Answer

와 작동합니다! 이렇게 금방 해결할 줄 몰랐내요 for문 돌려보는걸 생각 못하다니...답변 감사합니다!! ps. json을 담을 dto를 하나의 클래스로 만들수도 있나요? object 생성기에 복붙하고 그냥 사용했는데 갑자기 궁금증이 떠오르내요package userTest; import java.io.BufferedReader; import java.io.InputStreamReader; import java.net.HttpURLConnection; import java.net.URL; import java.util.Map; import com.fasterxml.jackson.core.type.TypeReference; import com.fasterxml.jackson.databind.ObjectMapper; public class JsonToObject { public static void main(String[] args) { String urlStr &#61; &#34;http://www.kobis.or.kr/kobisopenapi/webservice/rest/boxoffice/searchDailyBoxOfficeList.json&#34; &#43; &#34;?key&#61;430156241533f1d058c603178cc3ca0e&targetDt&#61;20200101&itemPerPage&#61;1&#34;; BoxOffice boxOffice &#61; null; BoxOfficeResult bresult &#61; null; DailyBoxOfficeList[] dlist&#61;null ; BufferedReader br &#61; null; try { URL url &#61; new URL(urlStr); HttpURLConnection urlconnection &#61;(HttpURLConnection) url.openConnection(); urlconnection.setRequestMethod(&#34;GET&#34;); br &#61; new BufferedReader(new InputStreamReader(urlconnection.getInputStream(),&#34;utf-8&#34;)); String result&#61;&#34;&#34;; String line; while((line &#61; br.readLine())!&#61; null) { result &#43;&#61;line&#43;&#34;
&#34;; } ObjectMapper mapper &#61; new ObjectMapper(); boxOffice &#61;mapper.readValue(result, BoxOffice.class); DailyBoxOfficeList[] list &#61; boxOffice.getBoxOfficeResult().getDailyBoxOfficeList(); for(DailyBoxOfficeList dailyBoxOfficeList : list) { System.out.println(dailyBoxOfficeList); System.out.println(&#34;영화재목 :&#34;&#43;dailyBoxOfficeList.getMovieNm()); System.out.println(&#34;상영일자 :&#34;&#43;dailyBoxOfficeList.getOpenDt()); /* *[rnum &#61; 1, audiCnt &#61; 498802, salesAcc &#61; 57336776690, scrnCnt &#61; 1236, * rankInten &#61; 0, salesShare &#61; 37.3, movieNm &#61; 백두산, salesAmt &#61; 4430968920, * movieCd &#61; 20192206, salesChange &#61; 75.1, audiInten &#61; 182606, * audiChange &#61; 57.8, rankOldAndNew &#61; OLD, rank &#61; 1, openDt &#61; 2019-12-19, * salesInten &#61; 1900850950, showCnt &#61; 5845, audiAcc &#61; 6789306] 영화재목 :백두산 상영일자 :2019-12-19 * */ } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } }

swp0419 · Answer

dto를 하나의 클래스로 만들수도 있나요? 이게 정확히 무슨말이신지..BoxOffice, BoxOfficeResult, DailyBoxOfficeList 클래스를 1개의 클래스에 합칠수 없냐고 물어보시는건가요?맞다는 가정하에 다음과 같이 가능 할거 같네요1. 통합 DTO 클래스 하나 만듭니다.public class BoxOffice { private BoxOfficeResult boxOfficeResult; // boxOfficeResult getter setter 생략 public static class BoxOfficeResult { private String boxofficeType; private String showRange; private DailyBoxOfficeInfo[] dailyBoxOfficeList; // boxofficeType, showRange, dailyBoxOfficeList getter setter 생략 } public static class DailyBoxOfficeInfo { private String rnum; private String audiCnt; // 변수 일부 및 getter setter 생략 }}생략이라고 작성한 부분은 만들어주세요.. 너무 길어서.. 2. 테스트 소스 변경ObjectMapper mapper &#61; new ObjectMapper(); boxOffice &#61; mapper.readValue(result, BoxOffice.class); System.out.println(&#34;boxOfficeResult > boxofficeType &#61; &#34; &#43; boxOffice.getBoxOfficeResult().getBoxofficeType()); BoxOffice.DailyBoxOfficeInfo[] dailyBoxOfficeList &#61; boxOffice.getBoxOfficeResult().getDailyBoxOfficeList(); for(BoxOffice.DailyBoxOfficeInfo dailyBoxOfficeInfo : dailyBoxOfficeList) { System.out.println(&#34;boxOfficeResult > dailyBoxOfficeList > movieNm &#61; &#34; &#43; dailyBoxOfficeInfo.getMovieNm()); }

jackson api로 json 데이터를 java object로 저장하는 방법이 궁금합니다.

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