在 Hibernate 中创建 POJO答案

【问题标题】：Creating POJOs in Hibernate在 Hibernate 中创建 POJO
【发布时间】：2017-12-25 22:37:04
【问题描述】：

我正在尝试创建 pojo。我的要求是根据策略 ID 检索用户信息。每个客户只有一个地址和一个政策。

所以我创建了三个 POJO。 Address.java、Customer.java、Policy.java。

地址.java

@Entity
@Table(name="CUSTOMER_ADDRESS")
public class Address {


    @Column(name="ADDRESS_STREET")
    private String address_street;

    @Column(name="ADDRESS_CITY")
    private String address_city;

    @Column(name="ADDRESS_STATE")
    private String address_state;

    @Column(name="ADDRESS_ZIPCODE")
    private String address_zipcode;

    @GenericGenerator(name = "generator", strategy = "foreign",
    parameters = @Parameter(name = "property", value = "CUSTOMER"))
    @Id
    @GeneratedValue(generator = "generator")
    @Column(name="CUSTOMER_ID")
    private int customer_id;
    public String getAddress_street() {
        return address_street;
    }
    public void setAddress_street(String address_street) {
        this.address_street = address_street;
    }
    public String getAddress_city() {
        return address_city;
    }
    public void setAddress_city(String address_city) {
        this.address_city = address_city;
    }
    public String getAddress_state() {
        return address_state;
    }
    public void setAddress_state(String address_state) {
        this.address_state = address_state;
    }
    public String getAddress_zipcode() {
        return address_zipcode;
    }
    public void setAddress_zipcode(String address_zipcode) {
        this.address_zipcode = address_zipcode;
    }
    public int getCustomer_id() {
        return customer_id;
    }
    public void setCustomer_id(int customer_id) {
        this.customer_id = customer_id;
    }



}

客户.java

@Entity
@Table(name="CUSTOMER")
public class Customer {

    private int customer_id;
    private String customer_name;
    private Date customer_dob;
    private Address address;
    private Policy policy;

    @OneToOne
    @JoinColumn(name = "CUSTOMER_ID")
    public Address getAddress() {
        return address;
    }
    public void setAddress(Address address) {
        this.address = address;
    }
    @OneToOne
    @JoinColumn(name = "CUSTOMER_ID")
    public Policy getPolicy() {
        return policy;
    }
    public void setPolicy(Policy policy) {
        this.policy = policy;
    }

    @Id
    @GeneratedValue(strategy = IDENTITY)
    @Column(name = "CUSTOMER_ID")
    public int getCustomer_id() {
        return customer_id;
    }
    public void setCustomer_id(int customer_id) {
        this.customer_id = customer_id;
    }

    @Column(name = "CUSTOMER_NAME")
    public String getCustomer_name() {
        return customer_name;
    }
    public void setCustomer_name(String customer_name) {
        this.customer_name = customer_name;
    }

    @Column(name = "CUSTOMER_DOB")
    public Date getCustomer_dob() {
        return customer_dob;
    }
    public void setCustomer_dob(Date customer_dob) {
        this.customer_dob = customer_dob;
    }

}

Policy.java

@Entity
@Table(name="CUSTOMER_POLICY_DETAILS")
public class Policy implements Serializable{

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    @Id
    @Column(name="POLICY_ID")
    int policy_id;

    @Column(name="POLICY_START_DATE")
    String policyStartDate;

    @Column(name="POLICY_END_DATE")
    String policyEndDate;

    @GenericGenerator(name = "generator", strategy = "foreign",
    parameters = @Parameter(name = "property", value = "CUSTOMER"))
    @Id
    @GeneratedValue(generator = "generator")
    @Column(name="CUSTOMER_ID")
    int customer_id;

    public int getCustomer_id() {
        return customer_id;
    }

    public void setCustomer_id(int customer_id) {
        this.customer_id = customer_id;
    }

    public Policy() {
        super();
    }

    public int getPolicy_id() {
        return policy_id;
    }



    public void setPolicy_id(int policy_id) {
        this.policy_id = policy_id;
    }



    public String getPolicyStartDate() {
        return policyStartDate;
    }

    public void setPolicyStartDate(String policyStartDate) {
        this.policyStartDate = policyStartDate;
    }

    public String getPolicyEndDate() {
        return policyEndDate;
    }

    public void setPolicyEndDate(String policyEndDate) {
        this.policyEndDate = policyEndDate;
    }


}

我应该在我的 Customer 类中包含 Address 对象和 Policy 对象吗？由于我在 Address 和 Policy 类中有 customer_id 属性，我不需要将它包含在我的 Customer 类中吗？

【问题讨论】：

标签： hibernate pojo

【解决方案1】：

我从您的描述中了解到。客户和地址之间的关系是一对一的，客户必须有地址和地址属于一个客户，并且对于政策也是如此。所以无论客户在地址中还是在客户中的地址都无关紧要 pojo .

所以在您的情况下，您将获得客户对象，然后是来自同一对象的地址和政策。我希望回答您的问题。

【讨论】：

【解决方案2】：

是的。在客户实体中包含address和policy实体是根据policy_id和address_id。为此，您需要在 customer 实体中包含 address 和 policy 实体的主键。根据您提供的代码，地址实体的连接列必须是 Address_id，策略实体的连接列必须是 policy_id。

您为 customer 中的两个映射指定了相同的名称实体。由于这些映射代表关系和外来键，各个实体的主键列的名称必须是您的加入列。
因为您只有 one-one 映射到其他实体的双向映射在这里不会造成任何问题。但是你应该很小心其他关系映射中的双向映射。

【讨论】：