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。
尽管能够实现，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,例如以下图，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。之后能够看到test数据库，单击就出现了course和teacher表，全选后点击Include,之后点finish，例如以下图
再来到Hibernate Code Generation Configuration窗口，首先配置下Output directory输出文件夹，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。
结果例如以下图：
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;
} }
到此我们就完毕了由数据库表生成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，最关键的是增加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就能够了。
终于结果如图：
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的朋友也能够借助ant脚本来实现，详细的教程去google吧。
这里推荐下HibernateTools的官方教程。包括了eclipse插件和ant脚本两种实现方式，很全面。