HibernateTools實現pojo類 數據庫schma mapping映射的相互轉換 二

接着上一篇博客：HibernateTools實現pojo類 數據庫schma mapping映射的相互轉換

思路二：由數據庫表，生成Mapping映射文件和POJO類。

   雖然可以實現，但個人覺着先設計數據庫，然後再生成類不符合Hibernate的面對對象持久化的思維方式。好了，還是說步驟吧，首先在test數據庫建立兩張表，分別爲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;

建好表後，在eclipse項目上右鍵-->new,如下圖，選擇框中的第三項，這個reveng.xml文件用於配置 選擇要生成POJO類的數據庫表。

選擇上篇博客中創建的Console configuration項，點Database schema框下的refresh，之後可以看到test數據庫，單擊就出現了course和teacher表，全選後點擊Include,之後點finish，如下圖

再來到Hibernate Code Generation Configuration窗體，首先配置下Output directory輸出目錄，在盡挨着的複選框打上勾，然後在package欄寫上生成文件要輸出到哪個包，並選擇剛配置好的reveng.xml文件

配置要輸出的項，這裏選定前兩項，生成.java和.hbm.xml，就是我們想要的POJO類和Mapping映射文件。之後點擊run就好了。

結果如下圖：

生成的Mapping映射文件的代碼

<?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類：

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;
    }

}

到此我們就完成了由數據庫表生成POJO類和Mapping映射文件的過程

思路三：由Mapping映射文件生成數據庫DDL和POJO類

首先，新建一個Mapping文件，這裏在項目中建立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>

接下來建一個新的Console Configuration文件，基本配置和上文中配置的過程一樣，最關鍵的是加入mapping文件。

接下來，改下Hibernate Code Generation Configuration就好了，首選選擇新配置的Console Configuration文件

接下來選擇要生成的Schema和.Java文件，然後run就可以了。

最終結果如圖：

生成的DDL代碼爲

create table DEPARTMENT (ID integer not null, NAME varchar(255), primary key (ID));</span>

POJO類：

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類，Mapping文件和數據庫表相互轉化就都介紹完了，當然這是藉助eclipse的插件實現的，熟悉使用ant的朋友也可以藉助ant腳本來實現，具體的教程去google吧。這裏推薦下HibernateTools的官方教程，包含了eclipse插件和ant腳本兩種實現方式，非常全面。