Hello, Python

JAVA, Optional

hwangyoungjae — Fri, 10 Dec 2021 12:12:47 +0900

1. Optional 객체 생성하기

1.1 Optional.of - 참조변수의 값이 null이 아닐때

Optional<String> optStr = Optional.of("Hello World!");
Optional<String> optStNull = Optional.of(null); // NullPointerException 발생

`of`로 Optional 객체를 생성할때 null을 인자로 사용하면 NullPointerException이 발생하기 때문에 반드시 값이 있어야 한다.

1.2 Optional.ofNullable - 참조변수의 값이 null일 가능성이 있을때

Optional<String> optStr = Optional.ofNullable("Hello World!");
Optional<String> optStrN = Optional.ofNullable(null);
System.out.printf("optStr : Present=%s, Empty=%s%n", optStr.isPresent(), optStr.isEmpty());
System.out.printf("optStrN: Present=%s, Empty=%s%n", optStrN.isPresent(), optStrN.isEmpty());

// 출력
optStr : Present=true, Empty=false
optStrN: Present=false, Empty=true

1.3 Optional.empty - 참조변수를 기본값(null)로 초기화할때

Optional<String> optStrN = Optional.empty();
System.out.printf("optStrN: Present=%s, Empty=%s%n", optStrN.isPresent(), optStrN.isEmpty());
        
// 출력
optStrN: Present=false, Empty=true

2. Optional 객체의 값 가져오기

2.1 T get() - 참조변수가 반드시 있을때

Optional<String> optStr = Optional.of("Hello World");
Optional<String> optStrN = Optional.empty();
String s1 = optStr.get();
String s2 = optStrN.get(); // NoSuchElementException 발생

2.2 T orElse(T other) - 참조변수가 없을때 값 대체

Optional<String> optStr = Optional.of("Hello World");
Optional<String> optStrN = Optional.empty();
System.out.println("optStr : " + optStr.orElse("Default value"));
System.out.println("optStrN: " + optStrN.orElse("Default value!"));

// 출력
optStr : Hello World
optStrN: Default value!

2.3 T orElseGet(Supplier<? extends T> supplier) - 참조변수가 없을때 람다식으로 대체

Optional<String> optStr = Optional.of("Hello World");
Optional<String> optStrN = Optional.empty();
System.out.println("optStr : " + optStr.orElseGet(() -> "Default value"));
System.out.println("optStrN: " + optStrN.orElseGet(() -> "Default value"));

// 출력
optStr : Hello World
optStrN: Default value

2.4 T orElseThrow(Supplier<? extends X> exceptionSupplier) - 참조변수가 null일때 예외 발생

Optional<String> optStr = Optional.of("Hello World");
Optional<String> optStrN = Optional.empty();
optStr.orElseThrow(IllegalStateException::new);
optStrN.orElseThrow(IllegalStateException::new); // IllegalStateException 발생

2.5 Optional<T> filter(Predicate<? super T> predicate) - 필터링해서 참조변수 가져오기

Optional<String> optStr1 = Optional.of("Hello World");
Optional<String> optStr2 = Optional.of("World Hello");
String s1 = optStr1.filter(s -> s.substring(0, 1).equals("H")).orElse("Default");
String s2 = optStr2.filter(s -> s.substring(0, 1).equals("H")).orElse("Default");
System.out.println("s1: " + s1);
System.out.println("s2: " + s2);

// 출력
s1: Hello World
s2: Default

2.6 boolean isPresent() - 참조변수 확인

Optional<String> optStr1 = Optional.ofNullable("youngjae");
Optional<String> optStr2 = Optional.ofNullable(null);

System.out.println("optStr1.isPresent() = " + optStr1.isPresent());
System.out.println("optStr2.isPresent() = " + optStr2.isPresent());

// 출력
optStr1.isPresent() = true
optStr2.isPresent() = false

2.7 void ifPresent(Consumer<? super T> action) - 참조변수 있으면 actino 호출

Optional<String> optStr1 = Optional.ofNullable("youngjae");
Optional<String> optStr2 = Optional.ofNullable(null);

optStr1.ifPresent(s -> System.out.println("optStr1: " + s));
optStr2.ifPresent(s -> System.out.println("optStr2: " + s));

// 출력
optStr1: youngjae

2.8 void ifPresentOrElse(Consumer<? super T> action, Runnable emptyAction) - 참조변수 있으면 action, 없으면 emptyActino 호출

Optional<String> optStr1 = Optional.ofNullable("youngjae");
Optional<String> optStr2 = Optional.ofNullable(null);

optStr1.ifPresentOrElse(
        s -> System.out.println("optStr1: " + s),
        () -> System.out.println("optStr1: novalue"));
optStr2.ifPresentOrElse(
        s -> System.out.println("optStr2: " + s),
        () -> System.out.println("optStr2: novalue"));
    }

// 출력
optStr1: youngjae
optStr2: novalue

2.9 Optional<U> map(Function<? super T, ? extends U> mapper) - 매핑

Optional<String> optStr1 = Optional.of("Hello World");
Optional<String> optStr2 = Optional.empty();
Integer s1 = optStr1.map(String::length).orElse(0);
Integer s2 = optStr2.map(String::length).orElse(0);
System.out.println("s1: " + s1);
System.out.println("s2: " + s2);

// 출력
s1: 11
s2: 0

2.10 Optional<U> flatMap(Function<? super T, ? extends Optional<? extends U>> mapper) - 리턴타입 Optional

map과 flatMap의 차이점을 보면서 flatMap의 특성을 살펴보겠음

map과 flatMap은 반환타입이 Optional인건 같지만, map은 람다식 return값을 Optional로 감싸서 주지만, flatMap은 직접 감싸야 한다 혹은 이미 감싸져 있는걸 그대로 사용할수 있다.

Member 객체에 getName이 Optinal타입으로 return해줄때 member의 name을 가져오는 예제를 가지고 비교해보자.

JPA에서 비식별 형태로 연관관계를 구성할때 Optional을 구성하고, 이때 flatMap을 통해 활용할수 있을것으로 생각된다.

예제에 사용된 Member class

public class Member {
    private String name = null;

    public Member() {
    }

    public Member(String name) {
        this.name = name;
    }

    public Optional<String> getName() {
        return Optional.ofNullable(name);
    }
}

Member m1 = new Member();
Member m2 = new Member("youngjae");
Optional<Member> optM1 = Optional.ofNullable(m1);
Optional<Member> optM2 = Optional.ofNullable(m2);

// map
String m1Name = optM1
        .map(member -> member.getName().orElse("noname"))
        .get();
String m2Name = optM2
        .map(member -> member.getName().orElse("noname"))
        .get();
System.out.println("map    , m1Name: " + m1Name);
System.out.println("map    , m2Name: " + m2Name);


// flatMap
String m1NameF = optM1
        .flatMap(Member::getName)
        .orElse("noname");
String m2NameF = optM2
        .flatMap(Member::getName)
        .orElse("noname");
System.out.println("flatMap, m1Name: " + m1NameF);
System.out.println("flatMap, m2Name: " + m2NameF);

map을 사용한 부분은 억지를 부린감이 없지않아 있지만, 어쨌든 flatMap을 사용하면 깔끔해진다.

참고:

자바의 정석 3판

https://mangkyu.tistory.com/70

https://madplay.github.io/post/difference-between-map-and-flatmap-methods-in-java

https://ryanwoo.tistory.com/48

JPA, Composite Key, IdClass

hwangyoungjae — Fri, 3 Dec 2021 10:25:11 +0900

복합키를 IdClass로 구성하여 입력 및 가져오는 code를 정리

N + 1 문제는 fetchjoin과 distinct로 해결하고자 했으며, 추후에 QueryDSL로도 정리 예정

Entity

@Entity @Table(name = "member")
@Getter @Setter
@EqualsAndHashCode(onlyExplicitlyIncluded = true)
public class Member {
    @EqualsAndHashCode.Include
    @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "member_id")
    private Long id;

    private String name;

    @OneToMany(mappedBy = "member", fetch = FetchType.LAZY)
    private List<AssociationMember> associationMembers = new ArrayList<>();
}

@Entity @Table(name = "association")
@Getter @Setter
@EqualsAndHashCode(onlyExplicitlyIncluded = true)
public class Association {
    @EqualsAndHashCode.Include
    @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "association_id")
    private Long id;

    private String name;

    @OneToMany(mappedBy = "association", fetch = FetchType.LAZY)
    private List<AssociationMember> associationMembers = new ArrayList<>();
}

@NoArgsConstructor @AllArgsConstructor
@EqualsAndHashCode(onlyExplicitlyIncluded = true)
public class AssociationMemberId implements Serializable {
    @EqualsAndHashCode.Include
    private Member member;
    @EqualsAndHashCode.Include
    private Association association;
}

@Entity @Table(name = "association_member")
@IdClass(AssociationMemberId.class)
@Getter @Setter
@EqualsAndHashCode(onlyExplicitlyIncluded = true)
public class AssociationMember {
    @EqualsAndHashCode.Include
    @Id @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "member_id")
    private Member member;

    @EqualsAndHashCode.Include
    @Id @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "association_id")
    private Association association;
}

DDL

create table `member`
(
    member_id bigint auto_increment primary key,
    name      varchar(255) null
);

create table `association`
(
    association_id bigint auto_increment primary key,
    name           varchar(255) null
);

create table `association_member`
(
    association_id bigint not null,
    member_id      bigint not null,
    primary key (association_id, member_id),
    constraint FKbhgfoulhcplvmuj5v3qg9k57q
        foreign key (association_id) references association (association_id),
    constraint FKe4bl75mb9i4m8ib5sw8otthay
        foreign key (member_id) references member (member_id)
);

Record setup

실행코드

public static void logic(EntityManager em) {
    for (int i = 1; i <= 3; i++) {
        Association association = new Association();
        association.setName("association" + i);
        em.persist(association);
    }

    Member member = new Member();
    member.setName("member");
    em.persist(member);

    for (int i = 1; i <= 3; i++) {
        AssociationMember am = new AssociationMember();
        am.setMember(member);
        am.setAssociation(em.find(Association.class, (long) i));
        em.persist(am);
    }
}

실행결과

Hibernate: insert into association (name) values (?)
Hibernate: insert into association (name) values (?)
Hibernate: insert into association (name) values (?)
Hibernate: insert into member (name) values (?)
Hibernate: select associatio0_.association_id as associat1_0_0_, associatio0_.name as name2_0_0_ from association associatio0_ where associatio0_.association_id=?
Hibernate: select associatio0_.association_id as associat1_0_0_, associatio0_.name as name2_0_0_ from association associatio0_ where associatio0_.association_id=?
Hibernate: select associatio0_.association_id as associat1_0_0_, associatio0_.name as name2_0_0_ from association associatio0_ where associatio0_.association_id=?
Hibernate: insert into association_member (association_id, member_id) values (?, ?)
Hibernate: insert into association_member (association_id, member_id) values (?, ?)
Hibernate: insert into association_member (association_id, member_id) values (?, ?)

값 가져오기

Member를 기준으로 Association 확인

실행

String jpql = "select distinct m from Member m join fetch m.associationMembers am join fetch am.association";
List<Member> members = em.createQuery(jpql, Member.class)
        .getResultList();
members.forEach(member -> {
    System.out.printf("> memberName: %s%n", member.getName());
    member.getAssociationMembers().forEach(am -> {
        System.out.printf(" > associationName: %s%n", am.getAssociation().getName());
    });
});

결과

Hibernate: select distinct member0_.member_id as member_i1_2_0_, associatio1_.association_id as associat1_1_1_, associatio1_.member_id as member_i2_1_1_, associatio2_.association_id as associat1_0_2_, member0_.name as name2_2_0_, associatio1_.member_id as member_i2_1_0__, associatio1_.association_id as associat1_1_0__, associatio2_.name as name2_0_2_ from member member0_ inner join association_member associatio1_ on member0_.member_id=associatio1_.member_id inner join association associatio2_ on associatio1_.association_id=associatio2_.association_id
Hibernate: select member0_.member_id as member_i1_2_0_, member0_.name as name2_2_0_ from member member0_ where member0_.member_id=?
> memberName: member
 > associationName: association1
 > associationName: association2
 > associationName: association3

AssociationMember를 기준으로 Member, Association 확인

실행

String jpql = "select am from AssociationMember am join fetch am.member m join fetch am.association a";
List<AssociationMember> resultList = em.createQuery(jpql, AssociationMember.class)
        .getResultList();
for (AssociationMember am : resultList) {
    System.out.printf("%s - %s%n", am.getMember().getName(), am.getAssociation().getName());
}

결과

Hibernate: select associatio0_.association_id as associat1_1_0_, associatio0_.member_id as member_i2_1_0_, member1_.member_id as member_i1_2_1_, associatio2_.association_id as associat1_0_2_, member1_.name as name2_2_1_, associatio2_.name as name2_0_2_ from association_member associatio0_ inner join member member1_ on associatio0_.member_id=member1_.member_id inner join association associatio2_ on associatio0_.association_id=associatio2_.association_id
member - association1
member - association2
member - association3

JPA, OneToMany, FetchType, fetch join+distinct

hwangyoungjae — Thu, 2 Dec 2021 18:16:07 +0900

- Entity의 OneToMany의 FetchType에 대해 어떤식으로 처리되는지 정리

- JPQL을 사용했을때 발생하는 N + 1 문제를 fetch join + distinct로 해결

1. 준비

1.1 DDL & Records

create table `member`
(
    member_id bigint auto_increment primary key,
    team_id   bigint       null,
    name      varchar(255) null
);
create table `team`
(
    team_id bigint auto_increment primary key,
    name    varchar(255) null
);

# member
member_id,team_id,name
1,1,m1
2,1,m2
3,1,m3
4,2,m4
5,2,m5
6,2,m6
7,3,m7
8,3,m8
9,4,m9
10,5,m10

# team
team_id,name
1,team1
2,team2
3,team3
4,team4
5,team5

1.2 Entity

@Getter @Setter
@Entity @Table(name = "manyToOne_member")
public class Member {
    @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "member_id")
    private Long id;
    private String name;

    @ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    @JoinColumn(name = "team_id")
    private Team team;
}

@Getter @Setter
@Entity @Table(name = "manyToOne_team")
public class Team {
    @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "team_id")
    private Long id;

    private String name;

    @OneToMany(mappedBy = "team", fetch = ?)
    private List<Member> members = new ArrayList<>();
}

1.3 표출하기

Team 객체와 Member객체를 보기좋게 표출하기 위한 method

public static void print(Team team) {
    String teamName = team.getName();
    List<String> memberNames = team.getMembers()
            .stream()
            .map(Member::getName)
            .collect(Collectors.toList());

    System.out.printf(">>> %s : ", teamName);
    memberNames.forEach((memberName) -> System.out.printf("%s,", memberName));
    System.out.println();
}

2. EntityManager.find

2.1 실행코드

public static void logic(EntityManager em) {
    Team team = em.find(Team.class, 1L);
    print(team);
}

2.2 FetchType.EAGER 실행결과(query 1회)

Hibernate: select team0_.team_id as team_id1_1_0_, team0_.name as name2_1_0_, members1_.team_id as team_id3_0_1_, members1_.member_id as member_i1_0_1_, members1_.member_id as member_i1_0_2_, members1_.name as name2_0_2_, members1_.team_id as team_id3_0_2_ from manyToOne_team team0_ left outer join manyToOne_member members1_ on team0_.team_id=members1_.team_id where team0_.team_id=?
>>> team1 : m1,m2,m3,

2.3 FetchType.LAZY 실행결과(query 2회)

Hibernate: select team0_.team_id as team_id1_1_0_, team0_.name as name2_1_0_ from manyToOne_team team0_ where team0_.team_id=?
Hibernate: select members0_.team_id as team_id3_0_0_, members0_.member_id as member_i1_0_0_, members0_.member_id as member_i1_0_1_, members0_.name as name2_0_1_, members0_.team_id as team_id3_0_1_ from manyToOne_member members0_ where members0_.team_id=?
>>> team1 : m1,m2,m3,

3. JPQL

3.1 Single

3.1.1 실행코드

String jpql = "select t from Team t where t.id=:id";
Team team = em.createQuery(jpql, Team.class)
        .setParameter("id", 1L)
        .getSingleResult();
print(team);

3.1.2 FetchType.EAGER 실행결과(query 2회)

Hibernate: select team0_.team_id as team_id1_1_, team0_.name as name2_1_ from manyToOne_team team0_ where team0_.team_id=?
Hibernate: select members0_.team_id as team_id3_0_0_, members0_.member_id as member_i1_0_0_, members0_.member_id as member_i1_0_1_, members0_.name as name2_0_1_, members0_.team_id as team_id3_0_1_ from manyToOne_member members0_ where members0_.team_id=?
>>> team1 : m1,m2,m3,

3.1.3 FetchType.LAZY 실행결과(query 2회)

Hibernate: select team0_.team_id as team_id1_1_, team0_.name as name2_1_ from manyToOne_team team0_ where team0_.team_id=?
Hibernate: select members0_.team_id as team_id3_0_0_, members0_.member_id as member_i1_0_0_, members0_.member_id as member_i1_0_1_, members0_.name as name2_0_1_, members0_.team_id as team_id3_0_1_ from manyToOne_member members0_ where members0_.team_id=?
>>> team1 : m1,m2,m3,

3.2 Multiple

3.2.1 실행코드

String jpql = "select t from Team t";
List<Team> teams = em.createQuery(jpql, Team.class)
        .getResultList();
for (Team team : teams) {
    print(team);
}

3.2.2 FetchType.EAGER 실행결과(query 6회)

Hibernate: select team0_.team_id as team_id1_1_, team0_.name as name2_1_ from manyToOne_team team0_
Hibernate: select members0_.team_id as team_id3_0_0_, members0_.member_id as member_i1_0_0_, members0_.member_id as member_i1_0_1_, members0_.name as name2_0_1_, members0_.team_id as team_id3_0_1_ from manyToOne_member members0_ where members0_.team_id=?
Hibernate: select members0_.team_id as team_id3_0_0_, members0_.member_id as member_i1_0_0_, members0_.member_id as member_i1_0_1_, members0_.name as name2_0_1_, members0_.team_id as team_id3_0_1_ from manyToOne_member members0_ where members0_.team_id=?
Hibernate: select members0_.team_id as team_id3_0_0_, members0_.member_id as member_i1_0_0_, members0_.member_id as member_i1_0_1_, members0_.name as name2_0_1_, members0_.team_id as team_id3_0_1_ from manyToOne_member members0_ where members0_.team_id=?
Hibernate: select members0_.team_id as team_id3_0_0_, members0_.member_id as member_i1_0_0_, members0_.member_id as member_i1_0_1_, members0_.name as name2_0_1_, members0_.team_id as team_id3_0_1_ from manyToOne_member members0_ where members0_.team_id=?
Hibernate: select members0_.team_id as team_id3_0_0_, members0_.member_id as member_i1_0_0_, members0_.member_id as member_i1_0_1_, members0_.name as name2_0_1_, members0_.team_id as team_id3_0_1_ from manyToOne_member members0_ where members0_.team_id=?
>>> team1 : m1,m2,m3,
>>> team2 : m4,m5,m6,
>>> team3 : m7,m8,
>>> team4 : m9,
>>> team5 : m10,

3.2.3 FetchType.LAZY 실행결과(query 6회)

Hibernate: select team0_.team_id as team_id1_1_, team0_.name as name2_1_ from manyToOne_team team0_
Hibernate: select members0_.team_id as team_id3_0_0_, members0_.member_id as member_i1_0_0_, members0_.member_id as member_i1_0_1_, members0_.name as name2_0_1_, members0_.team_id as team_id3_0_1_ from manyToOne_member members0_ where members0_.team_id=?
>>> team1 : m1,m2,m3,
Hibernate: select members0_.team_id as team_id3_0_0_, members0_.member_id as member_i1_0_0_, members0_.member_id as member_i1_0_1_, members0_.name as name2_0_1_, members0_.team_id as team_id3_0_1_ from manyToOne_member members0_ where members0_.team_id=?
>>> team2 : m4,m5,m6,
Hibernate: select members0_.team_id as team_id3_0_0_, members0_.member_id as member_i1_0_0_, members0_.member_id as member_i1_0_1_, members0_.name as name2_0_1_, members0_.team_id as team_id3_0_1_ from manyToOne_member members0_ where members0_.team_id=?
>>> team3 : m7,m8,
Hibernate: select members0_.team_id as team_id3_0_0_, members0_.member_id as member_i1_0_0_, members0_.member_id as member_i1_0_1_, members0_.name as name2_0_1_, members0_.team_id as team_id3_0_1_ from manyToOne_member members0_ where members0_.team_id=?
>>> team4 : m9,
Hibernate: select members0_.team_id as team_id3_0_0_, members0_.member_id as member_i1_0_0_, members0_.member_id as member_i1_0_1_, members0_.name as name2_0_1_, members0_.team_id as team_id3_0_1_ from manyToOne_member members0_ where members0_.team_id=?
>>> team5 : m10,

4. JPQL(distinct, fetch join)

4.1 Single(FetchType.LAZY)

4.1.1 실행코드

String jpql = "select distinct t from Team t join fetch t.members where t.id=:id";
List<Team> teams = em.createQuery(jpql, Team.class)
        .setParameter("id", 1L)
        .getResultList();
for (Team team : teams) {
    print(team);
}

4.1.2 실행결과(query 1회)

Hibernate: select distinct team0_.team_id as team_id1_1_0_, members1_.member_id as member_i1_0_1_, team0_.name as name2_1_0_, members1_.name as name2_0_1_, members1_.team_id as team_id3_0_1_, members1_.team_id as team_id3_0_0__, members1_.member_id as member_i1_0_0__ from manyToOne_team team0_ inner join manyToOne_member members1_ on team0_.team_id=members1_.team_id where team0_.team_id=?
>>> team1 : m1,m2,m3,

4.2 Multiple(FetchType.LAZY)

4.2.1 실행코드

String jpql = "select distinct t from Team t join fetch t.members";
List<Team> teams = em.createQuery(jpql, Team.class)
        .getResultList();
for (Team team : teams) {
    print(team);
}

4.2.2 실행결과(query 1회)

Hibernate: select distinct team0_.team_id as team_id1_1_0_, members1_.member_id as member_i1_0_1_, team0_.name as name2_1_0_, members1_.name as name2_0_1_, members1_.team_id as team_id3_0_1_, members1_.team_id as team_id3_0_0__, members1_.member_id as member_i1_0_0__ from manyToOne_team team0_ inner join manyToOne_member members1_ on team0_.team_id=members1_.team_id
>>> team1 : m1,m2,m3,
>>> team2 : m4,m5,m6,
>>> team3 : m7,m8,
>>> team4 : m9,
>>> team5 : m10,

JPA, ManyToOne, FetchType, fetch join

hwangyoungjae — Thu, 2 Dec 2021 16:55:27 +0900

- Entity의 ManyToOne의 FetchType에 대해 어떤식으로 처리되는지 정리

- JPQL을 사용했을때 발생하는 N + 1 문제를 fetch join으로 해결

1. 준비

1.1 DDL & Records

create table `member`
(
    member_id bigint auto_increment primary key,
    team_id   bigint       null,
    name      varchar(255) null
);
create table `team`
(
    team_id bigint auto_increment primary key,
    name    varchar(255) null
);

# member
member_id,team_id,name
1,<null>,m1
2,1,m2
3,2,m3
4,2,m4
5,3,m5
6,3,m6
7,4,m7
8,4,m8
9,5,m9
10,5,m10

# team
team_id,name
1,team1
2,team2
3,team3
4,team4
5,team5

1.2 Entity

@Getter @Setter
@Entity @Table(name = "member")
public class Member {
    @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "member_id")
    private Long id;
    private String name;

    @ManyToOne(fetch = ?, cascade = CascadeType.ALL)
    @JoinColumn(name = "team_id")
    private Team team;
}

@Getter @Setter
@Entity @Table(name = "team")
public class Team {
    @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "team_id")
    private Long id;
    private String name;
}

1.3 표출하기

Member 객체와 Team을 보기좋게 표출하기 위한 print method

public static void print(Member member) {
  String memberName = member.getName();
  String teamName = null;
  if (member.getTeam() != null) {
    teamName = member.getTeam().getName();
  }
  System.out.printf(">>> %s-%s%n", memberName, teamName);
}

2. EntityManager.find

2.1 실행코드

public static void logic(EntityManager em) {
  Member member = em.find(Member.class, 2L);
  print(member);

2.2 FetchType.EAGER 실행결과(query 1회)

Hibernate: select member0_.member_id as member_i1_0_0_, member0_.name as name2_0_0_, member0_.team_id as team_id3_0_0_, team1_.team_id as team_id1_1_1_, team1_.name as name2_1_1_ from member member0_ left outer join team team1_ on member0_.team_id=team1_.team_id where member0_.member_id=?
>>> m2-team1

2.3 FetchType.LAZY 실행결과(query 2회)

Hibernate: select member0_.member_id as member_i1_0_0_, member0_.name as name2_0_0_, member0_.team_id as team_id3_0_0_ from member member0_ where member0_.member_id=?
Hibernate: select team0_.team_id as team_id1_1_0_, team0_.name as name2_1_0_ from team team0_ where team0_.team_id=?
>>> m2-team1

3. JPQL

3.1 Single

3.1.1 실행코드

String jpql = "select m from Member m join fetch m.team where m.id=:id";
Member member = em.createQuery(jpql, Member.class)
  .setParameter("id", 2L).getSingleResult();
print(member);

3.1.2 FetchType.EAGER(query 2회)

Hibernate: select member0_.member_id as member_i1_0_, member0_.name as name2_0_, member0_.team_id as team_id3_0_ from member member0_ where member0_.member_id=?
Hibernate: select team0_.team_id as team_id1_1_0_, team0_.name as name2_1_0_ from team team0_ where team0_.team_id=?
>>> m2-team1

3.1.3 FetchType.LAZY(query 2회)

Hibernate: select member0_.member_id as member_i1_0_, member0_.name as name2_0_, member0_.team_id as team_id3_0_ from member member0_ where member0_.member_id=?
Hibernate: select team0_.team_id as team_id1_1_0_, team0_.name as name2_1_0_ from team team0_ where team0_.team_id=?
>>> m2-team1

3.2 Multiple

3.2.1 실행코드

String jpql = "select m from Member m";
List<Member> resultList = em.createQuery(jpql, Member.class)
  .getResultList();
for (Member member : resultList) {
  print(member);
}

3.2.2 FetchType.EAGER(query 6회)

Hibernate: select member0_.member_id as member_i1_0_, member0_.name as name2_0_, member0_.team_id as team_id3_0_ from member member0_
Hibernate: select team0_.team_id as team_id1_1_0_, team0_.name as name2_1_0_ from team team0_ where team0_.team_id=?
Hibernate: select team0_.team_id as team_id1_1_0_, team0_.name as name2_1_0_ from team team0_ where team0_.team_id=?
Hibernate: select team0_.team_id as team_id1_1_0_, team0_.name as name2_1_0_ from team team0_ where team0_.team_id=?
Hibernate: select team0_.team_id as team_id1_1_0_, team0_.name as name2_1_0_ from team team0_ where team0_.team_id=?
Hibernate: select team0_.team_id as team_id1_1_0_, team0_.name as name2_1_0_ from team team0_ where team0_.team_id=?
>>> m1-null
>>> m2-team1
>>> m3-team2
>>> m4-team2
>>> m5-team3
>>> m6-team3
>>> m7-team4
>>> m8-team4
>>> m9-team5
>>> m10-team5

3.2.3 FetchType.LAZY(query 6회)

Hibernate: select member0_.member_id as member_i1_0_, member0_.name as name2_0_, member0_.team_id as team_id3_0_ from manyToOne_member member0_
>>> m1-null
Hibernate: select team0_.team_id as team_id1_1_0_, team0_.name as name2_1_0_ from manyToOne_team team0_ where team0_.team_id=?
>>> m2-team1
Hibernate: select team0_.team_id as team_id1_1_0_, team0_.name as name2_1_0_ from manyToOne_team team0_ where team0_.team_id=?
>>> m3-team2
>>> m4-team2
Hibernate: select team0_.team_id as team_id1_1_0_, team0_.name as name2_1_0_ from manyToOne_team team0_ where team0_.team_id=?
>>> m5-team3
>>> m6-team3
Hibernate: select team0_.team_id as team_id1_1_0_, team0_.name as name2_1_0_ from manyToOne_team team0_ where team0_.team_id=?
>>> m7-team4
>>> m8-team4
Hibernate: select team0_.team_id as team_id1_1_0_, team0_.name as name2_1_0_ from manyToOne_team team0_ where team0_.team_id=?
>>> m9-team5
>>> m10-team5

4. JPQL(fetch join)

fetch join을 통한 N + 1 해결

4.1 Single(FetchType.LAZY)

4.1.1 실행코드

String jpql = "select m from Member m left join fetch m.team where m.id=:id";
Member member = em.createQuery(jpql, Member.class)
  .setParameter("id", 2L).getSingleResult();
print(member);

4.1.2 실행결과(query 1회)

Hibernate: select member0_.member_id as member_i1_0_0_, team1_.team_id as team_id1_1_1_, member0_.name as name2_0_0_, member0_.team_id as team_id3_0_0_, team1_.name as name2_1_1_ from member member0_ inner join team team1_ on member0_.team_id=team1_.team_id where member0_.member_id=?
>>> m2-team1

4.2 Multiple(FetchType.LAZY)

4.2.1 실행코드

String jpql = "select m from Member m left join fetch m.team";
List<Member> resultList = em.createQuery(jpql, Member.class)
  .getResultList();
for (Member member : resultList) {
  print(member);
}

4.2.2 실행결과(query 1회)

Hibernate: select member0_.member_id as member_i1_0_0_, team1_.team_id as team_id1_1_1_, member0_.name as name2_0_0_, member0_.team_id as team_id3_0_0_, team1_.name as name2_1_1_ from manyToOne_member member0_ left outer join manyToOne_team team1_ on member0_.team_id=team1_.team_id
>>> m2-team1
>>> m3-team2
>>> m4-team2
>>> m5-team3
>>> m6-team3
>>> m7-team4
>>> m8-team4
>>> m9-team5
>>> m10-team5
>>> m1-null

MySQL, JOIN문

hwangyoungjae — Tue, 30 Nov 2021 12:46:27 +0900

JOIN문을 사용하고는 있지만 제대로 알고 사용하고 있나 싶어서 다시한번 정리

* MYSQL에는 FULL JOIN은 없음 union을 통해서 구현 가능함

Tables

member

member_id	member_name	team_id
1	m1	0
2	m2	1
3	m3	1
4	m4	2

team

team_id	team_name
1	team1
2	team2
3	team3

SELECT JOIN

INNERT JOIN (JOIN)

SELECT * FROM `member` m
INNER JOIN `team` t ON t.team_id = m.team_id;

member_id	member_name	team_id	team_id	team_name
2	m2	1	1	team1
3	m3	1	1	team1
4	m4	2	2	team2

LEFT OUTER JOIN (LEFT JOIN)

SELECT * FROM `member` m
LEFT OUTER JOIN `team` t ON t.team_id = m.team_id;

member_id	member_name	team_id	team_id	team_name
2	m2	1	1	team1
3	m3	1	1	team1
4	m4	2	2	team2
1	m1	0	<null>	<null>

LEFT OUTER JOIN (LEFT JOIN) B IS NULL

SELECT * FROM `member` m
LEFT OUTER JOIN `team` t ON t.team_id = m.team_id
WHERE t.team_id IS NULL;

member_id	member_name	team_id	team_id	team_name
1	m1	0	<null>	<null>

RIGHT OUTER JOIN (RIGHT JOIN)

SELECT * FROM `member` m
RIGHT OUTER JOIN `team` t ON t.team_id = m.team_id;

member_id	member_name	team_id	team_id	team_name
2	m2	1	1	team1
3	m3	1	1	team1
4	m4	2	2	team2
<null>	<null>	<null>	3	team3

RIGHT OUTER JOIN (RIGHT JOIN) A IS NULL

SELECT * FROM `member` m
RIGHT OUTER JOIN `team` t ON t.team_id = m.team_id
WHERE m.team_id IS NULL;

member_id	member_name	team_id	team_id	team_name
<null>	<null>	<null>	3	team3

FULL JOIN -- mysql에는 full join이 없으므로 union으로 구현

SELECT * FROM `member` m
LEFT OUTER JOIN `team` t ON t.team_id = m.team_id
UNION
SELECT * FROM `member` m
RIGHT OUTER JOIN `team` t ON t.team_id = m.team_id;

member_id	member_name	team_id	team_id	team_name
2	m2	1	1	team1
3	m3	1	1	team1
4	m4	2	2	team2
1	m1	0	<null>	<null>
<null>	<null>	<null>	3	team3

FULL JOIN A IS NULL, B IS NULL -- mysql에는 full join이 없으므로 union으로 구현

SELECT * FROM `member` m
LEFT OUTER JOIN `team` t ON t.team_id = m.team_id
WHERE t.team_id IS NULL
UNION
SELECT * FROM `member` m
RIGHT OUTER JOIN `team` t ON t.team_id = m.team_id
where m.member_id IS NULL;

member_id	member_name	team_id	team_id	team_name
1	m1	0	<null>	<null>
<null>	<null>	<null>	3	team3

참고:

https://yoo-hyeok.tistory.com/98

개발을 잘하는 사람의 특징 다섯가지(feat, OJ Tube)

hwangyoungjae — Tue, 16 Nov 2021 06:52:03 +0900

유튜브에서 좋은 개발자라는 주제로 영상을 하나 시청하였는데,

공감가는 부분이 있어 기록을 위해 글을 하나 남기기로 하였다.

종종 개발주제로 시청하던 OJ tube에 오지완이란 분인데,

어떤 개발자가 좋은 개발자라고 생각하시는지, 될놈될은 좋은 습관과 좋은 태도를 몸에 이미 익혔기 때문에라는 말과 함께 타고난것이 아닌 노력으로 충분히 이룰수 있는 부분이라는 이야기도 해주었다.

내가 관심을 가지고 봤던 부분은 개발을 잘하는 사람의 특징 다섯가지이다.

첫번째, 모르고 막막한 일이 오더라도 포기하지 않는다. 압박감을 이겨낸다.
두번째, 일이 주어졌을때 시킨일만 하지 않고, 일의 본질이 무엇인지 파악하고 그에 맞게끔 일을 해결한다.
세번째,자기개발에 욕심이 있다. 계속 발전하려는 의지가 있다.
네번째, 성실하거나 똑똑하거나 성실한데 똑똑하거나
다섯번째, 어떤 지식을 습득했을때 조립을 잘한다. 개발자에게 필요한 능력, 새로운 지식을 습득했을때 끝이 아니라 그 지식을 다른 지식과 조합하여 활용할수 있는 능력

위 다섯가지는 영상 초반부에 나오는 내용이고 후반부에는 본인의 경험담을 비추어 사례를 말씀해주시니 혹시 이 글을 읽고 계신분이라면 영상을 시청해보시는것도 좋을것이란 생각이 든다.

MySQL, foreign key update,delete rule

hwangyoungjae — Fri, 29 Oct 2021 13:55:37 +0900

Update rule

cascade: 참조되는 테이블에서 데이터를 수정하면, 참조하는 테이블의 데이터도 함께 수정됨

set default: 참조되는 테이블에서 데이터를 수정하면, 참조하는 테이블의 데이터가 해당 필드의 default값으로 수정됨

set null: 참조되는 테이블에서 데이터를 수정하면, 참조하는 테이블의 데이터가 null로 수정됨

restrict: 참조하는 테이블에 데이터가 남아 있으면, 참조되는 테이블의 데이터를 수정할 수 없음

noaction: restrict와 동일 <- default

Delete rule

cascade: 참조되는 테이블에서 데이터를 삭제하면, 참조하는 테이블의 데이터도 함께 삭제

set default: 참조되는 테이블에서 데이터를 삭제하면, 참조하는 테이블의 데이터가 해당 필드의 default값으로 수정

set null: 참조되는 테이블에서 데이터를 삭제하면, 참조하는 테이블의 데이터가 null로 수정

restrict: 참조하는 테이블에 데이터가 남아 있으면, 참조되는 테이블의 데이터를 삭제할 수 없음

noaction: restrict와 동일 <- default

참고: http://tcpschool.com/mysql/mysql_constraint_foreignKey

JPA, DynamicUpdate, DynamicInsert

hwangyoungjae — Thu, 28 Oct 2021 20:37:42 +0900

org.hibernate.annotations.DynamicUpdate

수정된 데이터만 사용해서 동적으로 UPDATE문을 생성한다.

import org.hibernate.annotations.DynamicUpdate;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@DynamicUpdate
@Table(name = "MEMBER")
public class Member {
    @Id
    @Column(name = "ID")
    private String id;

    @Column(name = "NAME")
    private String name;

    @Column(name = "AGE")
    private Integer age;
    
    ...
}

아래 코드를 @DynamicUpdate를 사용했을때와 사용하지 않았을때

package jpabook.start;

import javax.persistence.*;
import java.util.List;

public class JpaMain {
    public static void main(String[] args) {
        EntityManagerFactory emf = Persistence.createEntityManagerFactory("jpabook");
        EntityManager em = emf.createEntityManager();
        EntityTransaction tx = em.getTransaction();

        try {
            tx.begin();
            logic(em);
            tx.commit();
        } catch (Exception e) {
            e.printStackTrace();
            tx.rollback();
        } finally {
            em.close();
        }
        emf.close();
    }

    private static void logic(EntityManager em) {
        Member member = em.find(Member.class, "id1");
        member.setAge(25);
        em.persist(member);
    }
}

@DynamicUpdate 미사용(기본)

UPDATE `MEMBER` SET `AGE`=?, `NAME`=? WHERE `ID`=?;

@DynamicUpdate 사용

UPDATE `MEMBER` SET `AGE`=? WHERE `ID`=?;

org.hibernate.annotations.DynamicInsert

데이터가 존재하는(null이 아닌) 필드만으로 INSERT문을 동적으로 생성한다.

import org.hibernate.annotations.DynamicInsert;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@DynamicInsert
@Table(name = "MEMBER")
public class Member {
    @Id
    @Column(name = "ID")
    private String id;

    @Column(name = "NAME")
    private String name;

    @Column(name = "AGE")
    private Integer age;
    
    ...
}

아래 코드를 @DynamicInsert를 사용했을때와 사용하지 않았을때

package jpabook.start;

import javax.persistence.*;
import java.util.List;

public class JpaMain {
    public static void main(String[] args) {
        EntityManagerFactory emf = Persistence.createEntityManagerFactory("jpabook");
        EntityManager em = emf.createEntityManager();
        EntityTransaction tx = em.getTransaction();

        try {
            tx.begin();
            logic(em);
            tx.commit();
        } catch (Exception e) {
            e.printStackTrace();
            tx.rollback();
        } finally {
            em.close();
        }
        emf.close();
    }

    private static void logic(EntityManager em) {
        Member member = new Member("id9");
        member.setName("황영재");
        member.setAge(null);
        em.persist(member);
    }
}

@DynamicInsert 미사용(기본)

INSERT INTO MEMBER(ID,NAME,AGE) VALUES(?, ?, ?);

@DynamicInsert 사용

INSERT INTO MEMBER(ID,NAME) VALUES(?, ?);

※ 참고

상황에 따라 다르지만 컬럼이 대략 30개 이상이 되면 기본 방법인 정적 수정 쿼리보다 @DynamicUpdate를 사용한 동적 수정 쿼리가 빠르다고 한다. 한 테이블에 컬럼이 30개 이상 된다는 것은 테이블 설계상 책임이 적절히 분리되지 않았을 가능성이 높다.

고 한다.

참고 및 출처

자바 ORM 표준 JPA 프로그래밍 저:김영한, 3장 영속성 관리

Spring, Dependency Injection 종류 생성자주입, 수정자주입, 필드주입

hwangyoungjae — Wed, 27 Oct 2021 14:16:37 +0900

생성자 주입

annotation

MsgProvider.java

package constructor.annotation;

import org.springframework.stereotype.Component;

@Component("provider")
public class MsgProvider {
    private String msg = "Hello World!(Constructor Injection annotation)";

    public String getMsg() {
        return msg;
    }
}

MsgRender.java

package constructor.annotation;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service("render")
public class MsgRender {
    private MsgProvider msgProvider;

    @Autowired
    public MsgRender(MsgProvider msgProvider) {
        this.msgProvider = msgProvider;
    }

    public void render() {
        System.out.println(msgProvider.getMsg());
    }
}

ConstructorConfig.java

package constructor.annotation;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@ComponentScan
@Configuration
public class ConstructorConfig {
}

Main.java

package constructor.annotation;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class Main {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(ConstructorConfig.class);
        MsgRender msgRender = ctx.getBean("render", MsgRender.class);
        msgRender.render();
    }
}

xml

MsgProvider.java

package constructor.xml;

public class MsgProvider {
    private String msg = "Hello World!(Constructor Injection xml)";

    public String getMsg() {
        return msg;
    }
}

MsgRender.java

package constructor.xml;

public class MsgRender {
    private MsgProvider msgProvider;

    public MsgRender(MsgProvider msgProvider) {
        this.msgProvider = msgProvider;
    }

    public void render() {
        System.out.println(msgProvider.getMsg());
    }
}

constructor-config.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
                           http://www.springframework.org/schema/beans/spring-beans.xsd">
    <bean id="provider"
          class="constructor.xml.MsgProvider">
    </bean>

    <bean id="render"
          class="constructor.xml.MsgRender">
        <constructor-arg ref="provider"/>
    </bean>
</beans>

Main.java

package constructor.xml;

import org.springframework.context.support.GenericXmlApplicationContext;

public class Main {
    public static void main(String[] args) {
        GenericXmlApplicationContext ctx = new GenericXmlApplicationContext("classpath:constructor-config.xml");
        MsgRender msgRender = ctx.getBean("render", MsgRender.class);
        msgRender.render();
    }
}

수정자 주입

annotation

MsgProvider.java

package setter.annotation;

import org.springframework.stereotype.Component;

@Component("provider")
public class MsgProvider {
    private String msg = "Hello World!(Setter Injection annotation)";

    public String getMsg() {
        return msg;
    }
}

MsgRender.java

package setter.annotation;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service("render")
public class MsgRender {
    private MsgProvider msgProvider;

    @Autowired
    public void setMsgProvider(MsgProvider msgProvider) {
        this.msgProvider = msgProvider;
    }

    public void render() {
        System.out.println(msgProvider.getMsg());
    }
}

SetterConfig.java

package setter.annotation;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@ComponentScan
@Configuration
public class SetterConfig {
}

Main.java

package setter.annotation;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class Main {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(SetterConfig.class);
        MsgRender render = ctx.getBean("render", MsgRender.class);
        render.render();
    }
}

xml

MsgProvider.java

package setter.xml;

public class MsgProvider {
    private String msg = "Hello World!(Setter Injection xml)";

    public String getMsg() {
        return msg;
    }
}

MsgRender.java

package setter.xml;

public class MsgRender {
    private MsgProvider msgProvider;

    public void setMsgProvider(MsgProvider msgProvider) {
        this.msgProvider = msgProvider;
    }

    public void render() {
        System.out.println(msgProvider.getMsg());
    }
}

setter-config.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:p="http://www.springframework.org/schema/p"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
                           http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="provider"
          class="setter.xml.MsgProvider"/>


    <bean id="render"
          class="setter.xml.MsgRender"
          p:msgProvider-ref="provider">
    </bean>

    <bean id="render_property"
          class="setter.xml.MsgRender">
        <property name="msgProvider" ref="provider"/>
    </bean>

</beans>

Main.java

package setter.xml;

import org.springframework.context.support.GenericXmlApplicationContext;

public class Main {
    public static void main(String[] args) {
        GenericXmlApplicationContext ctx = new GenericXmlApplicationContext("classpath:setter-config.xml");
        MsgRender msgRender = ctx.getBean("render", MsgRender.class);
        msgRender.render();

        MsgRender msgRender2 = ctx.getBean("render_property", MsgRender.class);
        msgRender2.render();
    }
}

필드 주입

annotation

MsgProvider.java

package field.annotation;

import org.springframework.stereotype.Component;

@Component("provider")
public class MsgProvider {
    private String msg = "Hello World!(Field Injection annotation)";

    public String getMsg() {
        return msg;
    }
}

MsgRender.java

package field.annotation;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service("render")
public class MsgRender {
    @Autowired
    private MsgProvider msgProvider;

    public void render() {
        System.out.println(msgProvider.getMsg());
    }
}

FieldConfig.java

package field.annotation;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@ComponentScan
@Configuration
public class FieldConfig {
}

Main.java

package field.annotation;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class Main {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(FieldConfig.class);
        MsgRender msgRender = ctx.getBean("render", MsgRender.class);
        msgRender.render();
    }
}

Python,tkinter Checkbutton

hwangyoungjae — Fri, 20 Jan 2017 15:04:04 +0900

Python,tkinter Checkbutton

생성자 : tkinter.Checkbutton(master=None, cnf={}, **kw)

Checkbutton은 체크박스와 같은 옵션의 번호를 표시하며,

사용자는 한번에 여러 옵션을 선택할수 있다.

ex) python_tkinter_004.py

# -*- encoding:utf8 -*-
# Python version in the development environment 2.7.11
import os
os.chdir(os.path.dirname(__file__))
from Tkinter import *

root = Tk()
CheckVar1 = IntVar()
CheckVar2 = IntVar()
c1 = Checkbutton(root, text="Music", variable=CheckVar1)
c2 = Checkbutton(root, text="Video", variable=CheckVar2)
c1.pack()
c2.pack()
root.mainloop()

https://github.com/hwangyoungjae/study/blob/master/python_tkinter_004.py

실행화면

python_tkinter_004.png

>> Checkbutton의 상태값 <<

normal : 보통의 상태

disabled : 체크버튼위젯을 사용할수 없는 비활성화 상태

active : 체크버튼위젯이 눌려있는 상태

>> Checkbutton에서 사용되는 parameter <<

parameter를 설명하기에 앞서 parameter값에 사용되는 값 또는 단위에 대하여 아래의 URL을 참조하여 보길 바람

http://blog.naver.com/dudwo567890/130167555486

-. activebackground [default value:'SystemButtonFace'] : color

Checkbutton위젯이 active상태일때 위젯의 배경색

-. activeforeground [default value:'SystemWindowText'] : color

Checkbutton위젯이 active상태일때 위젯의 문자열색

-. anchor [default value:'center']

Checkbutton위젯 안의 아이템(문자열,이미지)위치

값 : 'nw', 'n', 'ne', 'e', 'se', 's', 'sw', 'w', 'center'

-. background = bg [default value:'SystemButtonFace'] : color

Checkbutton위젯의 배경색

-. bitmap [default value:'']

Checkbutton위젯에 들어갈 이미지를 bitmap으로 지정한다.

값 : 'error', 'gray75', 'gray50', 'gray25', 'gray12', 'hourglass', 'info', 'questhead', 'question', 'warring'

-. borderwidth = bd [default value:'2'] : mm/pixel

Checkbutton위젯의 테두리두께

-. command [default value:''] :

Checkbutton위젯이 active상태가 될때 발생하는 프로시저를 지정

명령어묶기에 대한 자세한 내용은 아래의 URL을 확인하길 바람

http://blog.naver.com/dudwo567890/130167555308

-. compound [default value:'none']

Checkbutton위젯에 문자열과 이미지를 동시에 표시할때 사용

값은 문자열에 대한 이미지의 상대위치이다.

값 : 'bottom', 'center', 'left', 'none', 'right', 'top'

-. cursor [default value:'']

Checkbutton위젯의 마우스커서모양

값 : "arrow", "circle", "clock", "cross", "dotbox", "exchange", "fleur", "heart", "heart", "man", "mouse", "pirate", "plus", "shuttle", "sizing", "spider", "spraycan", "star", "target", "tcross", "trek", "watch" 등등

-. disabledforeground [default value:'SystemDisabledText'] : color

Checkbutton위젯이 disabled상태일때 위젯의 문자열색

-. font [default value:'TkDefaultFont'] : font

Checkbutton위젯에 표시할 문자열의 글꼴

값으로는 font객체가 사용되며, 글꼴객체생성방법은 아래 URL을 참조하길 바란다.

http://blog.naver.com/dudwo567890/130167555486

-. foreground = fg [default value:'SystemWindowText'] : color

Checkbutton위젯의 문자열색

-. height [default value:0] : number of characters

Checkbutton위젯의 세로크기

위젯에 image가 표시될경우, parameter값의 단위는 문자의 갯수가 아닌 pixel이 된다.(mm/pixel사용가능)

-. highlightbackground [default value:'SystemButtonFace'] : color

Checkbutton위젯이 선택되지 않았을때의 하이라이트색

-. highlightcolor [default value:'SystemWindowFrame'] : color

Checkbutton위젯이 선택되었을때의 하이라이트색

-. highlightthickness [default value:'1'] : mm/pixel

Checkbutton위젯이 선택되었을때와 선택되지 않았을때를 구분하는 하이라이트의 두께

-. image [default value:''] : image

Checkbutton위젯에 이미지객체를 이용하여 이미지를 표시한다.

이미지객체 생성방법은 아래 URL을 참조하길 바란다.

http://blog.naver.com/dudwo567890/130167555486

-. indicatoron [default value:1] : boolean

Checkbutton위젯의 indicator형태의 여부

-. justify [default value:'center']

Checkbutton위젯에 표시된문자가 여러행일경우 문자열의 정렬방법

값 : 'center', 'left', 'right'

-. offrelief [default value:'raised']

-. offvalue [default value:'0'] :

Checkbutton위젯의 체크박스가 해제될경우 연결된변수의 값은 0이 된다.

이 parameter를 이용하면 0대신 들어갈 값을 지정할수 있다.

-. onvalue [default value:'1'] :

Checkbutton위젯의 체크박스가 체크될경우 연결된변수의 값은 1이 된다.

이 parameter를 이용하면 1대신 들어갈 값을 지정할수 있다.

-. overrelief [default value:'']

Checkbutton위젯위에 마우스를 올렸을때 이 parameter에 지정한 값으로 테두리모양이 변한다.

값 : "flat", "groove", "raised", "ridge", "solid", "sunken"

-. padx [default value:'1'] : mm/pixel

Checkbutton위젯의 테두리와 내용사이의 가로여백

-. pady [default value:'1'] : mm/pixel

Checkbutton위젯의 테두리와 내용사이의 세로여백

-. relief [default value:'flat']

Checkbutton위젯의 테두리모양

값 : "flat", "groove", "raised", "ridge", "solid", "sunken"

-. selectcolor [default value:'SystemWindow'] : color

Checkbutton위젯의 체크박스의 배경색상

-. selectimage [default value:'']

-. state [default value:'normal']

Checkbutton위젯의 상태값

값 : 'active', 'disabled', 'normal'

-. takefocus [default value:'']

-. text [default value:''] :

Checkbutton위젯에 표시할 문자열

-. textvariable [default value:''] :

Checkbutton위젯에 표시할 문자열을 가져올 Tk변수

-. tristateimage [default value:'']

-. tristatevalue [default value:'']

-. underline [default value:-1] :

Checkbutton위젯에 표시된 문자열중 특정문자에 밑줄표시하기

값은 Button위젯에 표시된 문자열의 index값이며,

이 index위치에 밑줄을 표시한다.

예를들어 underline의 값이 0일경우 표시된문자열의 첫문자에 밑줄을 표시한다.

-. variable [default value:''] :

Checkbutton위젯의 현재상태를 추적하는 제어변수(Tk변수),

일반적으로 제어변수는 IntVar이며, 값이 0일땐 해제, 1일땐 설정을 의미한다.

offvalue와 onvalue를 이용하면 value값을 변경할수 있다.

-. width [default value:0] : number of characters

Checkbutton위젯의 가로크기

위젯에 image가 표시될경우, parameter값의 단위는 문자의 갯수가 아닌 pixel이 된다.(mm/pixel사용가능)

-. wraplength [default value:'0'] : mm/pixel

Checkbutton위젯의 문자열을 자동줄내림할 너비

값은 텍스트를 표시할 가로크기이며,

이 값에 맞춰서 표시된 문자열을 자동줄내림함