（十四）Hibernate中的多表操作：单向一对一

Posted 2020-09-19 专注改变人生。

案例一： 注解方式实现一对一

• UserBean.java

package bean;

import java.io.Serializable;

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

@Entity
@Table(name = "user")
public class UserBean implements Serializable {

    @Id
    private Integer userid;
    private String username;
    private String password;
    private String sex;
    @Column(name = "is_admin")
    private String isAdmin;

    @OneToOne
    @JoinColumn(name="userid")  //一定要设置@JoinColumn,否则报错 ，表示用本表中的userid字段与cardBean中的主键关联
    private CardBean cardBean;

    public UserBean(Integer userid, String username, String password,
            String sex, String isAdmin) {
        super();
        this.userid = userid;
        this.username = username;
        this.password = password;
        this.sex = sex;
        this.isAdmin = isAdmin;
    }

    public UserBean() {
    }

    public Integer getUserid() {
        return userid;
    }

    public void setUserid(Integer userid) {
        this.userid = userid;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getIsAdmin() {
        return isAdmin;
    }

    public void setIsAdmin(String isAdmin) {
        this.isAdmin = isAdmin;
    }

    public CardBean getCardBean() {
        return cardBean;
    }

    public void setCardBean(CardBean cardBean) {
        this.cardBean = cardBean;
    }

}

• CardBean.java

package bean;

import java.io.Serializable;

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

@Entity
@Table(name = "card")
public class CardBean implements Serializable {

    @Id
    @Column(name = "card_id")
    private Integer cardId;
    @Column(name = "card_name")
    private String cardName;

    public CardBean(Integer cardId, String cardName) {
        super();
        this.cardId = cardId;
        this.cardName = cardName;
    }

    public CardBean() {
    }

    public Integer getCardId() {
        return cardId;
    }

    public void setCardId(Integer cardId) {
        this.cardId = cardId;
    }

    public String getCardName() {
        return cardName;
    }

    public void setCardName(String cardName) {
        this.cardName = cardName;
    }

}

• 把含注解的bean添加到总配置文件中,

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案例二： 使用映射文件xml实现一对一

• CardBean.java

package bean;

/**
 * CardBean entity. @author MyEclipse Persistence Tools
 */

public class CardBean implements java.io.Serializable {

    // Fields

    private Integer cardId;
    private String cardName;

    // Constructors

    /** default constructor */
    public CardBean() {
    }

    /** minimal constructor */
    public CardBean(Integer cardId) {
        this.cardId = cardId;
    }

    /** full constructor */
    public CardBean(Integer cardId, String cardName) {
        this.cardId = cardId;
        this.cardName = cardName;
    }

    // Property accessors

    public Integer getCardId() {
        return this.cardId;
    }

    public void setCardId(Integer cardId) {
        this.cardId = cardId;
    }

    public String getCardName() {
        return this.cardName;
    }

    public void setCardName(String cardName) {
        this.cardName = cardName;
    }

}

• UserBean.java

package bean;

/**
 * UserBean entity. @author MyEclipse Persistence Tools
 */

public class UserBean implements java.io.Serializable {

    // Fields

    private Integer userid;
    private String username;
    private String password;
    private String sex;
    private String isAdmin;

    private CardBean cardBean;

    // Constructors

    /** default constructor */
    public UserBean() {
    }

    /** minimal constructor */
    public UserBean(Integer userid) {
        this.userid = userid;
    }

    /** full constructor */
    public UserBean(Integer userid, String username, String password,
            String sex, String isAdmin) {
        this.userid = userid;
        this.username = username;
        this.password = password;
        this.sex = sex;
        this.isAdmin = isAdmin;
    }

    // Property accessors

    public Integer getUserid() {
        return this.userid;
    }

    public void setUserid(Integer userid) {
        this.userid = userid;
    }

    public String getUsername() {
        return this.username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return this.password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getSex() {
        return this.sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getIsAdmin() {
        return this.isAdmin;
    }

    public void setIsAdmin(String isAdmin) {
        this.isAdmin = isAdmin;
    }

    public CardBean getCardBean() {
        return cardBean;
    }

    public void setCardBean(CardBean cardBean) {
        this.cardBean = cardBean;
    }

}

• 创建映射文件  UserBean.hbm.xml

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<!-- 
    Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
    <class name="bean.UserBean" table="user" catalog="test">
        <id name="userid" type="java.lang.Integer">
            <column name="userid" />
            <generator class="assigned"></generator>
        </id>
        <property name="username" type="java.lang.String">
            <column name="username" length="100" />
        </property>
        <property name="password" type="java.lang.String">
            <column name="password" />
        </property>
        <property name="sex" type="java.lang.String">
            <column name="sex" />
        </property>
        <property name="isAdmin" type="java.lang.String">
            <column name="is_admin" />
        </property>
        
        <!-- 配置单向一对一 -->
        <one-to-one name="cardBean" class="bean.CardBean" ></one-to-one>
    </class>
</hibernate-mapping>

• 创建映射文件  CardBean.hbm.xml

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<!-- 
    Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
    <class name="bean.CardBean" table="card" catalog="test">
        <id name="cardId" type="java.lang.Integer">
            <column name="card_id" />
            <generator class="assigned"></generator>
        </id>
        <property name="cardName" type="java.lang.String">
            <column name="card_name" />
        </property>
    </class>
</hibernate-mapping>

• 把映射文件添加到总配置文件中