hibernate注解方式实现一对多映射

首先是在hibernate.cfg.xml中引入要映射的class

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE hibernate-configuration PUBLIC

"-//Hibernate/Hibernate Configuration DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

<session-factory>

<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>

<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/test?useUnicode=true&amp;characterEncoding=GBK</property>

<property name="hibernate.connection.username">root</property>

<property name="hibernate.connection.password">sa</property>

<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>

<property name="show_sql">true</property>

<property name="hibernate.hbm2ddl.auto">update</property>

<mapping class="com.sszd.hibernate.Reader"/>

<mapping class="com.sszd.hibernate.Book"/>

</session-factory>

</hibernate-configuration>

我们分别看看reader.java和book.java文件

Reader.java

package com.sszd.hibernate;

import java.util.HashSet;

import java.util.Set;

import javax.persistence.CascadeType;

import javax.persistence.Column;

import javax.persistence.Entity;

import javax.persistence.FetchType;

import javax.persistence.GeneratedValue;

import javax.persistence.GenerationType;

import javax.persistence.Id;

import javax.persistence.OneToMany;

import javax.persistence.Table;

@Entity

@Table(name="reader")

public class Reader {

@Id

@Column(name="ID")

@GeneratedValue(strategy=GenerationType.AUTO)

private int id;

@Column(name="MENO")

private String meno;

@Column(name="NAME")

private String name;

@OneToMany(mappedBy = "reader", cascade = CascadeType.ALL, fetch = FetchType.LAZY)

private Set<Book> books = new HashSet<Book>();

public Reader()

{

}

public Set getBooks() {

return books;

}

public void setBooks(Set books) {

this.books = books;

}

public int getId() {

return id;

}

public void setId(int id) {

this.id = id;

}

public String getMeno() {

return meno;

}

public void setMeno(String meno) {

this.meno = meno;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

}

book.java

package com.sszd.hibernate;

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.ManyToOne;

import javax.persistence.Table;

@Entity

@Table(name="book")

public class Book {

@Id

@Column(name="ID")

@GeneratedValue(strategy=GenerationType.AUTO)

private int id;

@Column(name="TITLE")

private String title;

@ManyToOne(cascade = CascadeType.ALL, optional = false)

@JoinColumn(name="rea_id", referencedColumnName="id")//外键为sut_id，与student中的id关联

private Reader reader;

public int getId() {

return id;

}

public Reader getReader() {

return reader;

}

public void setReader(Reader reader) {

this.reader = reader;

}

public void setId(int id) {

this.id = id;

}

public String getTitle() {

return title;

}

public void setTitle(String title) {

this.title = title;

}

}

接下来是我们的本地测试用例

package com.sszd.main;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.Transaction;

import org.hibernate.cfg.AnnotationConfiguration;

import com.sszd.hibernate.Book;

import com.sszd.hibernate.Reader;

public class ReaderToBooks {

private static SessionFactory sessionFactory;

public static void main(String[] args) {

sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();

Session session = sessionFactory.openSession();

Reader r = new Reader();

r.setName("Reader zhang");

Book b1 = new Book();

b1.setTitle("title1");

Book b2 = new Book();

b2.setTitle("title2");

b1.setReader(r);

b2.setReader(r);

r.getBooks().add(b1);

r.getBooks().add(b2);

Transaction trx = session.beginTransaction();

session.save(r);

trx.commit();

session.close();

}

}