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程序问答发布时间：2022-06-02 发布网站：大佬教程 code.js-code.com

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如何解决Spring Data JPA - create @Composite key for the three tables？

开发过程中遇到Spring Data JPA - create @Composite key for the three tables的问题如何解决？下面主要结合日常开发的经验，给出你关于Spring Data JPA - create @Composite key for the three tables的解决方法建议，希望对你解决Spring Data JPA - create @Composite key for the three tables有所启发或帮助；

好吧，我知道您的意思，但我认为这不是您的意思。你说

实际上，我有三个表，库存，类别和产品。@manyToMany库存与类别之间的关系，以及@manyToMany 类别与产品之间的关系。

这有助于抽象地考虑这一点。用陈记法说的是

但是，这可能不是您的意思。这是有问题的，因为您将需要category为每个StockandProduct 关系建立一个新的实体。因此，如果您有一个ETF类别，那么 BobsBestETFs产品中的每个股票（实际上是每个实例化关系）都将复制它。

您的意思可能更像是通过aStock和Product与category属性的关系。

这允许许多产品都有很多库存，并且每种产品/库存关系都有特定的类别属性。您将遇到的问题是，您不想category成为一个属性，而是想要一个类别的查找表，如下所示：

我想这就是您要寻找的。使用复合ID实施起来应该相当简单，但是您显示的示例似乎有些过时或不清楚。最好找到更好的例子。这就是我对最后一个架构进行建模的方式。

@Entity
public class Stock {
    @ID @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long ID;
}
@Entity
@Data
public class Product {
    @ID @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long ID;
}
@Entity
public class category {
    @ID @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long ID;
}
@Entity
@Data
public class StockProduct {
    @EmbeddedID
    private StockProductPk ID;

    @manyToOne
    @mapsID("productID")
    private Product product;
    @manyToOne
    @mapsID("stockID")
    private Stock stock;

    @manyToOne
    private category category;
}
@Embeddable
@Data
public class StockProductPk implements serializable {
    private static final long serialVersionUID = 1L;
    private Long stockID;
    private Long productID;
}

And as an example to use it:

private voID create() {
    category catEtf = new category();
    categoryRepo.save(catEtf);
    Stock s1 = new Stock();
    stockRepo.save(s1);
    Product bobEtfs = new Product();
    productRepo.save(bobEtfs);

    // create a relationship
    StockProduct bs1 = new StockProduct();
    bs1.setID(new StockProductPk());
    bs1.setProduct(bobEtfs);
    bs1.setStock(s1);
    bs1.setcategory(catEtf);
    stockProductRepo.save(bs1); 
}
private voID read() {
    StockProduct sp1 = new StockProduct();
    Product p1 = new Product();
    p1.setID(1L);
    sp1.setProduct(p1);
    List<StockProduct> bobEtfs = stockProductRepo.findAll(Example.of(sp1, ExampleMatcher.matching()));
    System.out.println(bobEtfs);
}

解决方法

我开发了以下代码，但不确定如何将记录保存到数据库中。

Stock.java

@Entity
public class Stock implements serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = IDENTITY)
    @column(name = "STOCK_ID",unique = true,nullable = falsE)
    private Integer stockId;

    @column(name = "STOCK_CODE",nullable = false,length = 10)
    private String stockCode;

    @column(name = "STOCK_NAME",length = 20)
    private String stockName;

    // owner of the relationship
    @OneToMany(fetch = FetchType.LAZY,mappedBy = "linkPk.stock",cascade = CascadeType.ALL)
    private Set<StockCategoryProductLink> stockCategoryProductLinks = new HashSet<>(0);

    public Stock() {
    }

    public Stock(Integer stockId,String stockCode,String stockName,Set<StockCategoryProductLink> stockCategoryProductLinks) {
        super();
        this.stockId = stockId;
        this.stockCode = stockCode;
        this.stockName = stockName;
        this.stockCategoryProductLinks = stockCategoryProductLinks;
    }

    public Integer getStockId() {
        return stockId;
    }

    public void setStockId(Integer stockId) {
        this.stockId = stockId;
    }

    public String getStockCode() {
        return stockCode;
    }

    public void setStockCode(String stockCodE) {
        this.stockCode = stockCode;
    }

    public String getStockName() {
        return stockName;
    }

    public void setStockName(String stockName) {
        this.stockName = stockName;
    }

    public Set<StockCategoryProductLink> getStockCategoryProductLinks() {
        return stockCategoryProductLinks;
    }

    public void setStockCategoryProductLinks(Set<StockCategoryProductLink> stockCategoryProductLinks) {
        this.stockCategoryProductLinks = stockCategoryProductLinks;
    }
}

Product.java

public class Product implements serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = IDENTITY)
    @column(name = "PRODUCT_ID",nullable = falsE)
    private Integer productId;

    @column(name = "PRODUCt_name")
    private String productName;

    @column(name = "PRODUCT_CODE",length = 10)
    private String productCode;

    @OneToMany(mappedBy = "linkPk.product",cascade = { CascadeType.PERSIST,CascadeType.MERGE })
    private List<StockCategoryProductLink> userDepartmentRoleLinks;

    public Product(String productName,String productCodE) {
        this.productName = productName;
        this.productCode = productCode;
    }

    public Integer getProductId() {
        return productId;
    }

    public void setProductId(Integer productId) {
        this.productId = productId;
    }

    public String getProductName() {
        return productName;
    }

    public void setProductName(String productName) {
        this.productName = productName;
    }

    public String getProductCode() {
        return productCode;
    }

    public void setProductCode(String productCodE) {
        this.productCode = productCode;
    }

    public List<StockCategoryProductLink> getUserDepartmentRoleLinks() {
        return userDepartmentRoleLinks;
    }

    public void setUserDepartmentRoleLinks(List<StockCategoryProductLink> userDepartmentRoleLinks) {
        thiS.UserDepartmentRoleLinks = userDepartmentRoleLinks;
    }
}

Category.java

Entity
@Table(name = "category",catalog = "mkyongdb")
public class Category implements java.io.serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = IDENTITY)
    @column(name = "CATEGORY_ID",nullable = falsE)
    private Integer categoryId;

    @column(name = "NAME",length = 10)
    private String name;

    @column(name = "[DESC]",nullable = falsE)
    private String desc;

    @OneToMany(fetch = FetchType.LAZY,mappedBy = "linkPk.category")
    private Set<StockCategoryProductLink> stockCategories = new HashSet<>(0);

    public Category() {
    }

    public Category(String name,String desc) {
        this.name = name;
        this.desc = desc;
    }

    public Category(String name,String desc,Set<StockCategoryProductLink> stockCategories) {
        this.name = name;
        this.desc = desc;
        this.stockCategories = stockCategories;
    }

    public Integer getCategoryId() {
        return categoryId;
    }

    public void setCategoryId(Integer categoryId) {
        this.categoryId = categoryId;
    }

    public String getName() {
        return name;
    }

    public void setName(String Name) {
        this.name = name;
    }

    public String getDesc() {
        return desc;
    }

    public void setDesc(String desc) {
        this.desc = desc;
    }

    public Set<StockCategoryProductLink> getStockCategories() {
        return stockCategories;
    }

    public void setStockCategories(Set<StockCategoryProductLink> stockCategories) {
        this.stockCategories = stockCategories;
    }

}

StockCategoryProductLink.java

@Embeddable
public class StockCategoryProductLink implements serializable {
    private static final long serialVersionUID = 1L;

    @EmbeddedId
    private StockCategoryProductLinkId linkPk = new StockCategoryProductLinkId();

    @Transient
    public Stock getStock() {
        return getLinkPk().getStock();
    }

    @Transient
    public Category getCategory() {
        return getLinkPk().getCategory();
    }

    @Transient
    public Product getProduct() {
        return getLinkPk().getProduct();
    }


    public StockCategoryProductLinkId getLinkPk() {
        return linkPk;
    }

    public void setLinkPk(StockCategoryProductLinkId linkPk) {
        this.linkPk = linkPk;
    }
}

StockCategoryProductLinkId.java

@Embeddable
public class StockCategoryProductLinkId {
    @manyToOne(cascade = { CascadeType.PERSIST,CascadeType.MERGE })
    @Joincolumn(name = "CATEGORY_ID")
    private Category category;

    @manyToOne(cascade = { CascadeType.PERSIST,CascadeType.MERGE })
    @Joincolumn(name = "STOCK_ID")
    private Stock stock;

    @manyToOne(cascade = { CascadeType.PERSIST,CascadeType.MERGE })
    @Joincolumn(name = "PRODUCT_ID")
    private Product product;

    public Category getCategory() {
        return category;
    }

    public void setCategory(Category category) {
        this.category = category;
    }

    public Stock getStock() {
        return stock;
    }

    public void setStock(Stock stock) {
        this.stock = stock;
    }

    public Product getProduct() {
        return product;
    }

    public void setProduct(Product product) {
        this.product = product;
    }
}

@H_373_2@manyToManyApplication.java

@SpringBootApplication
public class ManyToManyApplication implements CommandLineRunner{

    public static void main(String[] args) {
        SpringApplication.run(ManyToManyApplication.class,args);
    }

    @Autowired
    private CategoryRepository categoryRepository;
    @Autowired
    private StockRepository stockRepository;
    @Autowired
    private ProductRepository productRepository;

    @Override
    public void run(String... args) throws Exception {
        saveDataFirstTime();

    }


    private void saveDataFirstTime() {
        // Category
        Category category1 = new Category("CONSUMER","CONSUMER COMPANY");
        categoryRepository.save(category1);

        // Product
        Product product = new Product("Product-1","AB");
        productRepository.save(product);

        // Stock
        Stock stock = new Stock();
        stock.setStockCode("7052");
        stock.setStockName("PADINI");

        // StockCategoryProductLink
        StockCategoryProductLink link = new StockCategoryProductLink();
        link.getLinkPk().setCategory(category1);
        link.getLinkPk().setProduct(product);
        link.getLinkPk().setStock(stock);

        stock.getStockCategoryProductLinks().add(link);

        stockRepository.save(stock);
    }
}

Error:

org.springframework.beans.factory.beanCreationException: Error creaTing bean with name 'entitymanagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]: Invocation of init method failed; nested exception is org.hibernate.AnnotationException: Use of @OneToMany or @manyToMany targeTing an unmapped class: com.example.entity.Stock.stockCategoryProductLinks[com.example.entity.StockCategoryProductLink]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1778) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:593) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1105) ~[spring-context-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867) ~[spring-context-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549) ~[spring-context-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:742) [spring-boot-2.1.6.RELEASE.jar:2.1.6.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:389) [spring-boot-2.1.6.RELEASE.jar:2.1.6.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:311) [spring-boot-2.1.6.RELEASE.jar:2.1.6.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1213) [spring-boot-2.1.6.RELEASE.jar:2.1.6.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1202) [spring-boot-2.1.6.RELEASE.jar:2.1.6.RELEASE]
    at com.example.ManyToManyApplication.main(ManyToManyApplication.java:20) [classes/:na]
Caused by: org.hibernate.AnnotationException: Use of @OneToMany or @manyToMany targeTing an unmapped class: com.example.entity.Stock.stockCategoryProductLinks[com.example.entity.StockCategoryProductLink]
    at org.hibernate.cfg.Annotations.CollectionBinder.bindManyToManySecondPass(CollectionBinder.java:1274) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
    at org.hibernate.cfg.Annotations.CollectionBinder.bindStarToManySecondPass(CollectionBinder.java:811) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
    at org.hibernate.cfg.Annotations.CollectionBinder$1.secondPass(CollectionBinder.java:736) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
    at org.hibernate.cfg.CollectionSecondPass.doSecondPass(CollectionSecondPass.java:54) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
    at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processSecondPasses(InFlightMetadataCollectorImpl.java:1696) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
    at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processSecondPasses(InFlightMetadataCollectorImpl.java:1664) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:287) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
    at org.hibernate.jpa.boot.internal.EntitymanagerFactoryBuilderImpl.metadata(EntitymanagerFactoryBuilderImpl.java:904) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
    at org.hibernate.jpa.boot.internal.EntitymanagerFactoryBuilderImpl.build(EntitymanagerFactoryBuilderImpl.java:935) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
    at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntitymanagerFactory(SpringHibernateJpaPersistenceProvider.java:57) ~[spring-orm-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.orm.jpa.LocalContainerEntitymanagerFactoryBean.createNativeEntitymanagerFactory(LocalContainerEntitymanagerFactoryBean.java:365) ~[spring-orm-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.orm.jpa.AbstractEntitymanagerFactoryBean.buildNativeEntitymanagerFactory(AbstractEntitymanagerFactoryBean.java:390) ~[spring-orm-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.orm.jpa.AbstractEntitymanagerFactoryBean.afterPropertiesSet(AbstractEntitymanagerFactoryBean.java:377) ~[spring-orm-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.orm.jpa.LocalContainerEntitymanagerFactoryBean.afterPropertiesSet(LocalContainerEntitymanagerFactoryBean.java:341) ~[spring-orm-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1837) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1774) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    ... 15 common frames omitted