zoukankan html css js c++ java

Hibernate注解(一对一、一对多、多对多)

JPA(Java Persistence API)通过注解或XML描述对象与关系表的映射关系，并将运行期的实体对象持久化到数据库中。

JPA是一个规范，是一个标准，Hibernate是实现了这个标准的开源框架。

1、引入hibernate-jpa-2.0-api-1.0.0.Final.jar JPA规范对应的hibernate的jar包

2、修改配置文件hibernate.cfg.xml 的映射关系<Mapping class="">

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration
    PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN"
    "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
    <session-factory>
        <!-- thread:一个线程中使用一个。获取session会话时使用-->
        <property name="current_session_context_class">thread</property>
        <!-- 是否显示SQL语句，值为布尔型，默认false -->
        <property name="hibernate.show_sql">true</property>
        <!-- 是否格式化显示sql语句，让显示更美观，值为布尔型，默认false -->
        <property name="hibernate.format_sql">false </property>
        <!-- 自动建表
            update:每次执行时，无表则建表，无列则建列，只增不减 
            create:每次启动的时候，删除原表，再次创建
            create-drop:每次启动时创建新表，当显式关闭sessionFactory时，删除表
        -->
        <property name="hibernate.hbm2ddl.auto">update</property>
        <!-- 连接数据库 -->
        <property name="hibernate.connection.url">jdbc:mysql://127.0.0.1:3306/zxd_db</property>
        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.username">zxd</property>
        <property name="hibernate.connection.password">123456</property>
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
        
        <!-- 读取注解 -->
        <mapping class="demo.entity.Book" />
            
    </session-factory>
</hibernate-configuration>

3、实体配置

package demo.entity;

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

import org.hibernate.annotations.GenericGenerator;
/**
 * 注解实体配置
 * JPA通过注解或XML描述对象与关系表的映射关系，并将运行期的实体对象持久化到数据库中。
 * @author Don
 * @date：日期：2017年4月19日 时间：上午10:43:00*
 * @version 1.0
 */

//标注实体
@Entity
//实体对应的表名，自动建库(若不写name，则表名与实体名保持一致)
@Table(name="tb_book")
public class Book {
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    //主键ID注解
    private int id;
    @Id
    @GenericGenerator(name="pk_uuid",strategy="uuid")
    @GeneratedValue(generator="pk_uuid")
    //生成UUID的主键注解
    private String uuid;
    @Column
    //列注解
    private String name;
    @Column
    private double price;
    
    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 double getPrice() {
        return price;
    }
    public void setPrice(double price) {
        this.price = price;
    }
    public String getUuid() {
        return uuid;
    }
    public void setUuid(String uuid) {
        this.uuid = uuid;
    }
}

4、数据库实务session创建

package demo.util;

import java.text.Annotation;

import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.cfg.Configuration;
import org.hibernate.classic.Session;

public class HibernateUtil {

    public static Session getCurrentSession() {

        /*注解调用使用AnnotationConfiguration 对象创建*/
        // 加载Hibernate配置信息,默认读取src下的hibernate.cfg.xml
        Configuration cfg = new AnnotationConfiguration().configure();
        // 也可以指定hibernate.cfg.xml 的路径加载
        // Configuration cfg1 = new Configuration().configure(Path);

        /*
         * 应用程序从SessionFactory（会话工厂）里获得Session(会话)实例。它在多个应用线程间进行共享。
         * 通常情况下，整个应用只有唯一的一个会话工厂,SessionFactory由Configuration对象创建，
         * 每个Hibernate配置文件，实际上是对SessionFactory的配置
         */
        // 试用配置信息构建sessionFactory
        SessionFactory factory = cfg.buildSessionFactory();
        
        Session session =factory.getCurrentSession();
        
        return session;
    }

}

5、测试建表和增删改查和XML配置映射一致

(一)、一对一映射(主键关联)

Card实体类

package demo.entity;


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.Table;

import org.hibernate.annotations.Cascade;
import org.hibernate.annotations.CascadeType;
import org.hibernate.annotations.GenericGenerator;
import org.hibernate.annotations.Parameter;

@Entity
@Table(name="ann_o2o_1_Card")
public class Card {
    @Id
    @GenericGenerator(name="CreateId",strategy="foreign",parameters={
            @Parameter(name="property",value="person")
    })
    @GeneratedValue(generator="CreateId")
    //身份证的主键依赖于Person
    private int id;
    @Column
    private String code;
    @OneToOne(mappedBy="card")
    @Cascade(CascadeType.ALL)
    private Person person;
    
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getCode() {
        return code;
    }
    public void setCode(String card) {
        this.code = card;
    }
    public Person getPerson() {
        return person;
    }
    public void setPerson(Person person) {
        this.person = person;
    }
}

View Code

Person实体类

package demo.entity;

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.PrimaryKeyJoinColumn;
import javax.persistence.Table;

import org.hibernate.annotations.Cascade;
import org.hibernate.annotations.CascadeType;

@Entity
@Table(name="ann_o2o_1_Person")
public class Person {
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private int id;
    @Column
    private String name;
    @OneToOne
    @PrimaryKeyJoinColumn
    @Cascade(CascadeType.ALL)
    //通过主键查询身份证
    private Card card;
    
    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 Card getCard() {
        return card;
    }
    public void setCard(Card card) {
        this.card = card;
    }
}

View Code

(二)、一对一映射(唯一外键)

Card实体类

package demo.entity;


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.Table;

import org.hibernate.annotations.Cascade;
import org.hibernate.annotations.CascadeType;

@Entity
@Table(name="ann_o2o_Card")
public class Card {
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private int id;
    @Column
    private String code;
    @OneToOne
    @Cascade(CascadeType.ALL)
    @JoinColumn(name="pid",unique=true)
    //生成外键列
    private Person person;
    
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getCode() {
        return code;
    }
    public void setCode(String card) {
        this.code = card;
    }
    public Person getPerson() {
        return person;
    }
    public void setPerson(Person person) {
        this.person = person;
    }
}

View Code

Person实体类

package demo.entity;

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.Table;

import org.hibernate.annotations.Cascade;
import org.hibernate.annotations.CascadeType;

@Entity
@Table(name="ann_o2o_Person")
public class Person {
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private int id;
    @Column
    private String name;
    @OneToOne(mappedBy="person")
    @Cascade(CascadeType.ALL)
    private Card card;
    
    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 Card getCard() {
        return card;
    }
    public void setCard(Card card) {
        this.card = card;
    }
}

View Code

(三)、一对多映射

Classes实体类(课程)

package demo.entity;

import java.util.ArrayList;
import java.util.List;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;

import org.hibernate.annotations.Cascade;
import org.hibernate.annotations.CascadeType;



@Entity
@Table(name="ann_m2o_Classes")
public class Classes {
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private int id;
    @Column
    private String name;
    @OneToMany(mappedBy="cal")
    @Cascade(CascadeType.ALL)
    //一对多关系配置(配置Student实体中的Class实体映射对象，设计级联关系)
    private List<Student> list = new ArrayList<Student>();
    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 List<Student> getList() {
        return list;
    }
    public void setList(List<Student> list) {
        this.list = list;
    }
}

View Code

Student实体类(学生)

package demo.entity;

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.ManyToOne;
import javax.persistence.Table;

import org.hibernate.annotations.Cascade;
import org.hibernate.annotations.CascadeType;

@Entity
@Table(name="ann_m2o_Student")
public class Student {
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private int id;
    @Column
    private String name;
    @ManyToOne
    @JoinColumn(name="cid")
    @Cascade(CascadeType.SAVE_UPDATE)
    private Classes cal;
    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 Classes getCal() {
        return cal;
    }
    public void setCal(Classes cal) {
        this.cal = cal;
    }
    
}

View Code

(四)、多对多映射(中间表)

Course实体类(选课)

package demo.entity;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.Table;

import org.hibernate.annotations.Cascade;
import org.hibernate.annotations.CascadeType;
import org.hibernate.annotations.GenericGenerator;

/**
 * 课程实体
 * @author Don
 * @date：日期：2017年4月11日 时间：下午2:25:45*
 * @version 1.0
 */

@Entity
@Table(name="ann_m2m_Course")
public class Course {
    @Id
    @GenericGenerator(name="pk_key",strategy="uuid")
    @GeneratedValue(generator="pk_key")
    private String id;
    @Column
    private String name; 
    @ManyToMany
    //级联关系
    @Cascade(CascadeType.SAVE_UPDATE)
    //中间表
    @JoinTable(name="ann_m2m_stu_course",
    //链接当前对象的Id
    joinColumns={@JoinColumn(name="cid",referencedColumnName="id")},
    //链接对方的表的Id
    inverseJoinColumns={@JoinColumn(name="stuId",referencedColumnName="id")})
    private Set<Student> stus = new HashSet<>();
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Set<Student> getStus() {
        return stus;
    }
    public void setStus(Set<Student> stus) {
        this.stus = stus;
    }
    
    public Course(){}
    
    public Course(String name) {
        this.setName(name);
    }
}

View Code

Student实体类(选课人员)

package demo.entity;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinColumns;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.Table;

import org.hibernate.annotations.Cascade;
import org.hibernate.annotations.CascadeType;
import org.hibernate.annotations.GenericGenerator;

/**
 * 学生实体
 * @author Don
 * @date：日期：2017年4月11日 时间：下午2:25:15*
 * @version 1.0
 */
@Entity
@Table(name="ann_m2m_Student")
public class Student {
    @Id
    //生成UUID
    @GenericGenerator(name="pk_key",strategy="uuid")
    @GeneratedValue(generator="pk_key")
    private String id;
    @Column
    private String name;
    
    @ManyToMany
    //级联关系
    @Cascade(CascadeType.SAVE_UPDATE)
    //中间表
    @JoinTable(name="ann_m2m_stu_course",
    //链接当前对象的Id
    joinColumns={@JoinColumn(name="stuId",referencedColumnName="id")},
    //链接对方的表的Id
    inverseJoinColumns={@JoinColumn(name="cid",referencedColumnName="id")})
    private Set<Course> cous=new HashSet<>();
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Set<Course> getCous() {
        return cous;
    }
    public void setCous(Set<Course> cous) {
        this.cous = cous;
    }
    
    public Student() {
        
    }
    
    public Student(String name) {
        this.setName(name);
    }
}

View Code

查看全文

相关阅读:
PIE-Basic 自定义滤波
 PIE-Basic 常用滤波
 PIE-Basic 中值滤波
 PIE-Basic 均值滤波
 PIE-Basic 小波变换
 PIE-Basic 傅里叶变换
 PIE-Basic 去相关拉伸
 .net调用数据库执行Mysql存储过程，提示 Procedure or function XXXX Cannot be found in database xxx
C#几种类型转换方法的个人总结
 Winform无法改变窗体大小

原文地址：https://www.cnblogs.com/zxd543/p/6734559.html