Hibernate OneToOne注解关联查询案例

hibernate 的OneToOne注解是把两张表关联起来
下面是案例：
把User（用户表）表和Customer（客户表）关联起来
User表对应的实体类如下：

package com.pms.login.pojo;import java.util.Date;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.GenerationType;import javax.persistence.Id;import javax.persistence.SequenceGenerator;import javax.persistence.Table;import javax.persistence.UniqueConstraint;import org.springframework.format.annotation.DateTimeFormat;import com.fasterxml.jackson.annotation.JsonFormat;@Entity@Table(name="MAPS_MST_STAFF")@SequenceGenerator (name = "SEQ", sequenceName = "MST_STAFF_SEQ", allocationSize = 1) public class User {    @Id      @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "SEQ")     @Column(name = "id")      private Integer id;    //员工编号    @Column(name="STAFF_ID")    private String staffId;    //员工姓名    @Column(name="STAFF_NAME")    private String staffName;    //登录名    @Column(name="STAFF_LOGIN_NAME")    private String staffLoginName;    //员工角色    @Column(name="STAFF_CHARACTOR")    private String staffCharactor;    //开始时间    @Column(name="START_DT")    @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")    private Date startDate;    //结束时间    @Column(name="END_DT")    @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")    private Date endDate;    //联系电话    @Column(name="STAFF_TEL")    private String staffTel;    //员工性别    @Column(name="STAFF_SEX")    private String staffSex;    //密码    @Column(name="STAFF_PASS")    private String staffPass;    //密码有效期    @Column(name="PASS_END_DT")    @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")    private Date passEndDate;    //是否能登陆    @Column(name="LOGIN_FLG")    private String loginFlg;    public User(){    }    public User(Integer id, String staffId, String staffName, String staffLoginName, String staffCharactor,            Date startDate, Date endDate, String staffTel, String staffSex, String staffPass, Date passEndDate,            String loginFlg) {        super();        this.id = id;        this.staffId = staffId;        this.staffName = staffName;        this.staffLoginName = staffLoginName;        this.staffCharactor = staffCharactor;        this.startDate = startDate;        this.endDate = endDate;        this.staffTel = staffTel;        this.staffSex = staffSex;        this.staffPass = staffPass;        this.passEndDate = passEndDate;        this.loginFlg = loginFlg;    }    public Integer getId() {        return id;    }    public void setId(Integer id) {        this.id = id;    }    public String getStaffId() {        return staffId;    }    public void setStaffId(String staffId) {        this.staffId = staffId;    }    public String getStaffName() {        return staffName;    }    public void setStaffName(String staffName) {        this.staffName = staffName;    }    public String getStaffLoginName() {        return staffLoginName;    }    public void setStaffLoginName(String staffLoginName) {        this.staffLoginName = staffLoginName;    }    public String getStaffCharactor() {        return staffCharactor;    }    public void setStaffCharactor(String staffCharactor) {        this.staffCharactor = staffCharactor;    }    public Date getStartDate() {        return startDate;    }    public void setStartDate(Date startDate) {        this.startDate = startDate;    }    public Date getEndDate() {        return endDate;    }    public void setEndDate(Date endDate) {        this.endDate = endDate;    }    public String getStaffTel() {        return staffTel;    }    public void setStaffTel(String staffTel) {        this.staffTel = staffTel;    }    public String getStaffSex() {        return staffSex;    }    public void setStaffSex(String staffSex) {        this.staffSex = staffSex;    }    public String getStaffPass() {        return staffPass;    }    public void setStaffPass(String staffPass) {        this.staffPass = staffPass;    }    public Date getPassEndDate() {        return passEndDate;    }    public void setPassEndDate(Date passEndDate) {        this.passEndDate = passEndDate;    }    public String getLoginFlg() {        return loginFlg;    }    public void setLoginFlg(String loginFlg) {        this.loginFlg = loginFlg;    }    @Override    public String toString() {        return "User [id=" + id + ", staffId=" + staffId + ", staffName=" + staffName + ", staffLoginName="                + staffLoginName + ", staffCharactor=" + staffCharactor + ", startDate=" + startDate + ", endDate="                + endDate + ", staffTel=" + staffTel + ", staffSex=" + staffSex + ", staffPass=" + staffPass                + ", passEndDate=" + passEndDate + ", loginFlg=" + loginFlg + "]";    }}

这表没什么特别的，关键是customer表实体类：

package com.pms.projectsys.pojo;import java.util.Date;import javax.persistence.CascadeType;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.GenerationType;import javax.persistence.Id;import javax.persistence.JoinColumn;import javax.persistence.OneToOne;import javax.persistence.SequenceGenerator;import javax.persistence.Table;import org.springframework.format.annotation.DateTimeFormat;import com.fasterxml.jackson.annotation.JsonFormat;import com.pms.login.pojo.User;@Entity@Table(name="MAPS_MST_PJ_CUSTOMER")@SequenceGenerator (name = "CUSTOMER_SEQ", sequenceName = "MAPS_MST_PJ_CUSTOMER_SEQ", allocationSize = 1) public class Customer {    //客户ID    @Id      @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "CUSTOMER_SEQ")     @Column(name = "CUSTOMER_ID")      private Integer customerId;    //客户名称    @Column(name="CUSTOMER_NAME")    private String customerName;    //创建时间    @Column(name="CREATION_TIME")    @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")    private Date creationTime;    //创建人ID    @Column(name="CREATION_USER_ID",updatable=false)    private Integer creationUserId;    //修改时间    @Column(name="MODIFIED_TIME")    @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")    private Date modifiedTime;    //修改人ID    @Column(name="MODIFIED_USER_ID")    private Integer modifiedUserId;    @OneToOne(optional = true, cascade = CascadeType.ALL)      @JoinColumn(name = "creation_user_id",referencedColumnName="id",updatable=false,insertable=false)     private User creationUser;    public User getCreationUser() {        return creationUser;    }    public void setCreationUser(User creationUser) {        this.creationUser = creationUser;    }    @OneToOne(optional = true, cascade = CascadeType.ALL)      @JoinColumn(name = "modified_user_id",referencedColumnName="id",updatable=false,insertable=false)     private User modifiedUser;    @javax.persistence.Transient    private String creationUserName;    public String getCreationUserName() {        return creationUserName;    }    public void setCreationUserName(String creationUserName) {        this.creationUserName = creationUserName;    }    @javax.persistence.Transient    private String modifiedUserName;    public String getModifiedUserName() {        return modifiedUserName;    }    public void setModifiedUserName(String modifiedUserName) {        this.modifiedUserName = modifiedUserName;    }    @Override    public String toString() {        return "Customer [customerId=" + customerId + ", customerName=" + customerName + ", creationTime="                + creationTime + ", creationUserId=" + creationUserId + ", modifiedTime=" + modifiedTime                + ", modifiedUserId=" + modifiedUserId + ", creationUser=" + creationUser + ", modifiedUser="                + modifiedUser + ", creationUserName=" + creationUserName + ", modifiedUserName=" + modifiedUserName                + "]";    }    public Customer(){    }    public Customer(Integer customerId, String customerName, User creationUser,  Date creationTime,            User modifiedUser,Date modifiedTime) {        super();        this.customerId = customerId;        this.customerName = customerName;        this.creationTime = creationTime;        this.modifiedTime = modifiedTime;        this.creationUserId=creationUser.getId();        this.modifiedUserId=modifiedUser.getId();        this.creationUserName=creationUser.getStaffName();        this.modifiedUserName=modifiedUser.getStaffName();    }    public User getModifiedUser() {        return modifiedUser;    }    public void setModifiedUser(User modifiedUser) {        this.modifiedUser = modifiedUser;    }    public Integer getCustomerId() {        return customerId;    }    public void setCustomerId(Integer customerId) {        this.customerId = customerId;    }    public String getCustomerName() {        return customerName;    }    public void setCustomerName(String customerName) {        this.customerName = customerName;    }    public Date getCreationTime() {        return creationTime;    }    public void setCreationTime(Date creationTime) {        this.creationTime = creationTime;    }    public Integer getCreationUserId() {        return creationUserId;    }    public void setCreationUserId(Integer creationUserId) {        this.creationUserId = creationUserId;    }    public Date getModifiedTime() {        return modifiedTime;    }    public void setModifiedTime(Date modifiedTime) {        this.modifiedTime = modifiedTime;    }    public Integer getModifiedUserId() {        return modifiedUserId;    }    public void setModifiedUserId(Integer modifiedUserId) {        this.modifiedUserId = modifiedUserId;    }}

在Customer实体类里面
增加一个Use类型的属性，

    @OneToOne(optional = true, cascade = CascadeType.ALL)      @JoinColumn(name = "creation_user_id",referencedColumnName="id",updatable=false,insertable=false)     private User creationUser;

在属性上加上OneToOne注解，并且指明两个实体类表以哪个字段关联起来的，

@JoinColumn(name = "creation_user_id",referencedColumnName="id",updatable=false,insertable=false) 

@JoinColumn这个注解属性里面：
name指向Customer对应的表里面所要关联的字段
referencedColumnName指向User对应的表，里面所要关联的字段
这样就把两张表通过字段关联起来了