Setup a simplest Spring Project Demo Project

A Spring Demo project. See: https://github.com/digitalsonic/geektime-spring-family

Where to start

1. Spring initializr (recommended)
2. Create project from your IDE: IntelliJ, or Eclipse, etc..

Spring Boot & JPA with H2

0. Gradle dependency

build.gradle

implementation 'org.springframework.boot:spring-boot-starter'
compileOnly 'org.projectlombok:lombok'
developmentOnly 'org.springframework.boot:spring-boot-devtools'
annotationProcessor 'org.springframework.boot:spring-boot-configuration-processor'
annotationProcessor 'org.projectlombok:lombok'
testImplementation 'org.springframework.boot:spring-boot-starter-test'
implementation 'org.springframework.boot:spring-boot-starter-data-jpa'
compile 'com.h2database:h2'
testImplementation 'org.springframework.boot:spring-boot-starter-test'
compile 'org.joda:joda-money:1.0.1'
implementation 'org.jadira.usertype:usertype.core:6.0.1.GA'

Note: from offical website, joda money gradle dependency uses compile 'org.joda:joda-money:1.0.2-SNAP-SHOT' which is wrong.

1. Entity

1. Base Entity
   • Abstraction of multiple entites
   • @MappedSuperclass
   • no toString() method
   • createTime is not updatable

    @MappedSuperclass
    @Data
    @NoArgsConstructor
    @AllArgsConstructor
    public class BaseEntity implements Serializable {
        @Id
        @GeneratedValue
        private Long id;
   
        @Column(updatable = false)
        @CreationTimestamp
        private LocalDateTime createTime;
   
        @UpdateTimestamp
        private LocalDateTime updateTime;
    }
   

2. Enum

    public enum OrderState {
        INIT, PAID, BREWING, BREWED, TAKEN,CANCELLED
    }
   

3. Entity
   • Be careful of the Money joda.PersistentMoneyAmount
   • Extends base entity
   • in toString, uses callSuper = true
   • @Enumerated

    @Entity
    @Table(name = "T_MENU")
    @Builder
    @Data
    @ToString(callSuper = true)
    @NoArgsConstructor
    @AllArgsConstructor
    public class Coffee extends BaseEntity implements Serializable {
   
        private String name;
        @Column
        @Type(type = "org.jadira.usertype.moneyandcurrency.joda.PersistentMoneyAmount",
                parameters = {@org.hibernate.annotations.Parameter(name = "currencyCode", value = "CNY")})
        private Money price;
    }
   

    @Entity
    @Table(name = "T_ORDER")
    @Data
    @ToString(callSuper = true)
    @NoArgsConstructor
    @AllArgsConstructor
    @Builder
    public class CoffeeOrder extends BaseEntity implements Serializable {
   
        private String customer;
        @ManyToMany
        @JoinTable(name = "T_ORDER_COFFEE")
        @OrderBy("id")
        private List<Coffee> items;
   
        @Enumerated
        @Column(nullable = false)
        private Integer state;
    }
   

2. Repository

1. Base Repository

   • @NoRepositoryBean

    @NoRepositoryBean
    public interface BaseRepository<T, Long> extends PagingAndSortingRepository<T, Long> {
        List<T> findTop3ByOrderByUpdateTimeDescIdAsc();
    }
   

2. Regular repositories

   • extends base repository

    public interface CoffeeRepository extends BaseRepository<Coffee, Long> {}
   
    public interface CoffeeOrderRepository extends BaseRepository<CoffeeOrder, Long> {
        List<CoffeeOrder> findByCustomerOrderById(String customer);
        List<CoffeeOrder> findByItems_Name(String name);
    }
   

3. Main method

• @SpringBootApplication
• @EnableJpaRepositories

4. application.properties

spring.jpa.hibernate.ddl-auto=create-drop
spring.jpa.properties.hibernate.show_sql=true
spring.jpa.properties.hibernate.format_sql=true

references

• https://github.com/digitalsonic/geektime-spring-family
• https://www.baeldung.com/spring-data-redis-tutorial