java -Hibernate不能正確讀取數據庫中的對象

Question

我有一些問題根據Hibernate。

我有一個或多或少複雜的對象結構，我想使用Hibernate EntityManager（版本4.3.5.Final）保存/加載。我設法保存它，但如果我試圖讀取obejct，只有PK會被讀取。即使使用正確的PK，EntityManager的find方法也會返回null，所以我使用它的getReference方法。

我仍然有使用正確的關係（ManyToOne等）的麻煩，所以我很可能犯了一個錯誤，我想這是造成這個問題。 反正。

我的問題是：我如何堅持使用Hibernate這樣的對象結構？

下面是我使用的POJO：

編輯：更新代碼

CalculationList：

@Entity(name = "calculation") 
public class CalculationList implements EntityList { 

@Id 
private Date created; 

@OneToMany(mappedBy = "", fetch = FetchType.EAGER, cascade = CascadeType.ALL) 
private List<Product> products; 

public CalculationList(Date created) { 
    this.created = created; 
    this.products = new LinkedList<>(); 
} 

public CalculationList(Date created, List<Product> products) { 
    this.created = created; 
    this.products = products; 
} 

public CalculationList() { 
} 

public Date getCreated() { 
    return created; 
} 

public void setCreated(Date created) { 
    this.created = created; 
} 

public List<Product> getProducts() { 
    return products; 
} 

public void setProducts(List<Product> entities) { 
    this.products = entities; 
} 

@Override 
public String toString() { 
    return "CalculationList{" + 
      "created=" + created + 
      ", products=" + products + 
      '}'; 
} 
} 

CalulatorEntity：

@Entity(name = "calculator_entity") 
public class CalculatorEntity implements Serializable { 

@Id 
private int id; 

private CalculatorEntityType type; 

private String name; 

private int number; 

@ManyToOne(cascade = CascadeType.ALL) 
private Product product; 

public CalculatorEntity(CalculatorEntityType type) { 
    this.type = type; 
} 

protected CalculatorEntity() { 
} 

public int getNumber() { 
    return number; 
} 

public void setNumber(int number) { 
    this.number = number; 
} 

public Product getProduct() { 
    return product; 
} 

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

public int getId() { 
    return id; 
} 

public void setId(int id) { 
    this.id = id; 
} 

public CalculatorEntityType getType() { 
    return type; 
} 

public void setType(CalculatorEntityType type) { 
    this.type = type; 
} 

public String getName() { 
    return name; 
} 

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

public enum CalculatorEntityType { 
    GAS_PUMP, DELIVERY_BILL; 
} 

@Override 
public String toString() { 
    return "CalculatorEntity{" + 
      "id=" + id + 
      ", type=" + type + 
      ", name='" + name + '\'' + 
      ", product=" + product + 
      ", number=" + number + 
      '}'; 
} 
} 

產品：

@Entity(name = "product") 
public class Product implements Serializable { 

@Id 
private int id; 

private String name; 

private ProductType type; 

@OneToMany(mappedBy = "product", fetch = FetchType.EAGER, cascade = CascadeType.ALL) 
private List<CalculatorEntity> entities; 

public Product(String name, ProductType type) { 
    this.name = name; 
    this.type = type; 
    this.entities = new LinkedList<>(); 
} 

/** 
* JPA - Konstruktor 
*/ 
public Product() { 
} 

public int getId() { 
    return id; 
} 

public void setId(int id) { 
    this.id = id; 
} 

public String getName() { 
    return name; 
} 

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

public ProductType getType() { 
    return type; 
} 

public void setType(ProductType type) { 
    this.type = type; 
} 

public List<CalculatorEntity> getEntities() { 
    return entities; 
} 

public void setEntities(List<CalculatorEntity> entities) { 
    this.entities = entities; 
} 

@Override 
public String toString() { 
    return "Product{" + 
      "id=" + id + 
      ", name='" + name + '\'' + 
      ", type=" + type + 
      ", entities=" + entities + 
      '}'; 
} 

public enum ProductType { 

    FUEL("Treibstoff"), OIL("Öl"), OTHER("Verschiedenes"); 

    private String name; 

    private ProductType(String name) { 
     this.name = name; 
    } 

    public String getName() { 
     return this.name; 
    } 
} 
} 

Answer 1

你正在使用的不是映射Product類@OneToMany映射與錯誤的實體，您正在映射CalculationList類，移動以下配置：

@OneToMany(mappedBy = "product", fetch = FetchType.EAGER, cascade = CascadeType.ALL) 
private List<CalculatorEntity> entities; 

到Product類。