接着上一篇博客： HibernateTools实现pojo类 数据库schma mapping映射的相互转换
思路二：由数据库表，生成Mapping映射文件和POJO类。
虽然可以实现，但个人觉着先设计数据库，然后再生成类不符合Hibernate的面对对象持久化的思维方式。好了，还是说步骤吧，首先在test数据库建立两张表，分别为course表和teacher表
-- ---------------------------- -- Table structure for course -- ---------------------------- DROP TABLE IF EXISTS `course`; CREATE TABLE `course` ( `id` int(11) NOT NULL, `name` varchar(255) DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; -- ---------------------------- -- Table structure for teacher -- ---------------------------- DROP TABLE IF EXISTS `teacher`; CREATE TABLE `teacher` ( `id` int(11) NOT NULL, `name` varchar(255) DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8;建好表后，在eclipse项目上右键-->new,如下图，选择框中的第三项，这个reveng.xml文件用于配置 选择要生成POJO类的数据库表。
选择上篇博客中创建的Console configuration项，点Database schema框下的refresh，之后可以看到test数据库，单击就出现了course和teacher表，全选后点击Include,之后点finish，如下图
再来到Hibernate Code Generation Configuration窗体，首先配置下Output directory输出目录，在尽挨着的复选框打上勾，然后在package栏写上生成文件要输出到哪个包，并选择刚配置好的reveng.xml文件
配置要输出的项，这里选定前两项，生成.java和.hbm.xml，就是我们想要的POJO类和Mapping映射文件。之后点击run就好了。
结果如下图：
生成的Mapping映射文件的代码
<?xml version="1.0"?><!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"><!-- Generated 2014-5-31 11:19:19 by Hibernate Tools 4.0.0 --><hibernate-mapping><class name="org.hibernate.test.Course" table="course" catalog="test"><id name="id" type="int"><column name="id" /><generator class="assigned" /></id><many-to-one name="teacher" class="org.hibernate.test.Teacher" fetch="select"><column name="teacherId" not-null="true" /></many-to-one><property name="name" type="string"><column name="name" /></property></class></hibernate-mapping>
<?xml version="1.0"?><!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"><!-- Generated 2014-5-31 11:19:19 by Hibernate Tools 4.0.0 --><hibernate-mapping><class name="org.hibernate.test.Teacher" table="teacher" catalog="test"><id name="id" type="int"><column name="id" /><generator class="assigned" /></id><property name="name" type="string"><column name="name" /></property><set name="courses" table="course" inverse="true" lazy="true" fetch="select"><key><column name="teacherId" not-null="true" /></key><one-to-many class="org.hibernate.test.Course" /></set></class></hibernate-mapping>
生成的POJO类：
package org.hibernate.test;
// Generated 2014-5-31 11:19:19 by Hibernate Tools 4.0.0
/**
* Course generated by hbm2java
*/
public class Course implements java.io.Serializable {
private int id;
private Teacher teacher;
private String name;
public Course() {
}
public Course(int id, Teacher teacher) {
this.id = id;
this.teacher = teacher;
}
public Course(int id, Teacher teacher, String name) {
this.id = id;
this.teacher = teacher;
this.name = name;
}
public int getId() {
return this.id;
}
public void setId(int id) {
this.id = id;
}
public Teacher getTeacher() {
return this.teacher;
}
public void setTeacher(Teacher teacher) {
this.teacher = teacher;
}
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
}package org.hibernate.test;
// Generated 2014-5-31 11:19:19 by Hibernate Tools 4.0.0
import java.util.HashSet;
import java.util.Set;
/**
* Teacher generated by hbm2java
*/
public class Teacher implements java.io.Serializable {
private int id;
private String name;
private Set courses = new HashSet(0);
public Teacher() {
}
public Teacher(int id) {
this.id = id;
}
public Teacher(int id, String name, Set courses) {
this.id = id;
this.name = name;
this.courses = courses;
}
public int getId() {
return this.id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
public Set getCourses() {
return this.courses;
}
public void setCourses(Set courses) {
this.courses = courses;
}
}到此我们就完成了由数据库表生成POJO类和Mapping映射文件的过程
思路三：由Mapping映射文件生成数据库DDL和POJO类
首先，新建一个Mapping文件，这里在项目中建立Department.hbm.xml。
<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" ><hibernate-mapping><class name="org.hibernate.test.Department" table="DEPARTMENT"><id name="id" type="int"><column name="ID" /><generator class="increment"></generator></id><property name="name" type="java.lang.String"><column name="NAME" /></property></class></hibernate-mapping>
接下来建一个新的Console Configuration文件，基本配置和上文中配置的过程一样，最关键的是加入mapping文件。
接下来，改下Hibernate Code Generation Configuration就好了，首选选择新配置的Console Configuration文件
接下来选择要生成的Schema和.Java文件，然后run就可以了。
最终结果如图：
生成的DDL代码为
create table DEPARTMENT (ID integer not null, NAME varchar(255), primary key (ID));</span>
POJO类：
package org.hibernate.test;
// Generated 2014-5-31 16:23:27 by Hibernate Tools 4.0.0
/**
* Department generated by hbm2java
*/
public class Department implements java.io.Serializable {
private int id;
private String name;
public Department() {
}
public Department(String name) {
this.name = name;
}
public int getId() {
return this.id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
}好了，至此POJO类，Mapping文件和数据库表相互转化就都介绍完了，当然这是借助eclipse的插件实现的，熟悉使用ant的朋友也可以借助ant脚本来实现，具体的教程去google吧。这里推荐下 HibernateTools的官方教程，包含了eclipse插件和ant脚本两种实现方式，非常全面。
作者：xqf309 发表于2014-5-31 22:27:37 原文链接
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