用myeclipse的Hibernate 反向引擎 生成 数据库的 entity

把 Myeclipse 转到DB Browser

 

新建一个Database Connection driver

 

然后找到要反向工程的表

 

右键->Hibernate Reverse Engineering

然后，选好entity缩放的目录

对 Create POJO<>DB Table mapping information 打钩

然后点选 AddHibernate mapping annotations to POJO

再点选Update Hibernate configuration with mapping resource location

 

其他钩全部去掉，点击下一步，直至结束就可以

 

这样生成的entity

 

这里只说一对多和多对一

 

例：用户和组为多对一关系，双向

 

用户类：

package com.hibernate.entity;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

/**
* Tuser entity. @author MyEclipse Persistence Tools
*/
@Entity
@Table(name = "tuser", catalog = "test")
public class Tuser implements java.io.Serializable {

// Fields

/**
*
*/
private static final long serialVersionUID = -7792597282750540598L;
private Integer id;
private Tgroup tgroup;
private String name;

// Constructors

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

/** full constructor */
public Tuser(Tgroup tgroup, String name) {
this.tgroup = tgroup;
this.name = name;
}

// Property accessors
@Id
@GeneratedValue
@Column(name = "id", unique = true, nullable = false)
public Integer getId() {
return this.id;
}

public void setId(Integer id) {
this.id = id;
}

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "groupid")
public Tgroup getTgroup() {
return this.tgroup;
}

public void setTgroup(Tgroup tgroup) {
this.tgroup = tgroup;
}

@Column(name = "name")
public String getName() {
return this.name;
}

public void setName(String name) {
this.name = name;
}

}

 

组类：

package com.hibernate.entity;

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.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;

/**
* Tgroup entity. @author MyEclipse Persistence Tools
*/
@Entity
@Table(name = "tgroup", catalog = "test")
public class Tgroup implements java.io.Serializable {

// Fields

/**
*
*/
private static final long serialVersionUID = -7208715716759269846L;
private Integer id;
private String name;
private Set<Tuser> tusers = new HashSet<Tuser>(0);

// Constructors

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

/** full constructor */
public Tgroup(String name, Set<Tuser> tusers) {
this.name = name;
this.tusers = tusers;
}

// Property accessors
@Id
@GeneratedValue
@Column(name = "id", unique = true, nullable = false)
public Integer getId() {
return this.id;
}

public void setId(Integer id) {
this.id = id;
}

@Column(name = "name")
public String getName() {
return this.name;
}

public void setName(String name) {
this.name = name;
}

@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "tgroup")
public Set<Tuser> getTusers() {
return this.tusers;
}

public void setTusers(Set<Tuser> tusers) {
this.tusers = tusers;
}

}

 

<?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">

<!-- Generated by MyEclipse Hibernate Tools.                   -->
<hibernate-configuration>

<session-factory>
<property name="dialect">
org.hibernate.dialect.MySQLDialect
</property>
<property name="connection.url">
jdbc:mysql://localhost/test
</property>
<property name="connection.username">root</property>
<property name="connection.password">root</property>
<property name="connection.driver_class">
com.mysql.jdbc.Driver
</property>

<!-- JDBC connection pool (use the built-in) -->
<property name="connection.pool_size">1</property>

<!-- Enable Hibernate's automatic session context management -->
<property name="current_session_context_class">thread</property>

<!-- Disable the second-level cache  -->
<property name="cache.provider_class">
org.hibernate.cache.NoCacheProvider
</property>

<!-- Echo all executed SQL to stdout -->
<property name="show_sql">true</property>

<property name="format_sql">true</property>
<!--
<mapping class="com.hibernate.entity.Husband" />
<mapping class="com.hibernate.entity.Wife" />
===================================================
<mapping class="com.hibernate.entity.Teacher" />
<mapping class="com.hibernate.entity.Student" />
-->

<mapping class="com.hibernate.entity.Tgroup" />
<mapping class="com.hibernate.entity.Tuser" />
</session-factory>

</hibernate-configuration>

 

这里会抛错，原因是user类中没有写cascade = CascadeType.ALL

在Tuser类的@ManyToOne(fetch = FetchType.LAZY)中加上cascade = CascadeType.ALL就可以了

@Test
public void saveUser() {
Tgroup g = new Tgroup();
g.setName("g1");

Tuser u = new Tuser();
u.setName("u1");
u.setTgroup(g);

Session s = sessionFactory.getCurrentSession();
s.beginTransaction();
s.save(u);
s.getTransaction().commit();//这里会抛错，原因是user类中没有写cascade = CascadeType.ALL
，而默认是不写的。	}

 

 

这个方法也可以持久化两个类

@Test
public void saveGroup() {
Tgroup g = new Tgroup();
g.setName("g1");

Tuser u = new Tuser();
u.setName("u1");
u.setTgroup(g);

g.getTusers().add(u);

Session s = sessionFactory.getCurrentSession();
s.beginTransaction();
s.save(g);

s.getTransaction().commit();
}