1。创建数据库
在这个例子中,我们将MySQL数据库。创建下面两个表在MySQL。需要注意的是Employee和Department表显示出一个一对多的关系。每个部门可以assosiated多个员工,每个员工只能有一个部门。
CREATE TABLE `department` (
`department_id` BIGINT(20) NOT NULL AUTO_INCREMENT,
`dept_name` VARCHAR(50) NOT NULL DEFAULT '0',
PRIMARY KEY (`department_id`)
)
COLLATE='latin1_swedish_ci'
ENGINE=InnoDB
ROW_FORMAT=DEFAULT
AUTO_INCREMENT=115
CREATE TABLE `employee` (
`employee_id` BIGINT(10) NOT NULL AUTO_INCREMENT,
`firstname` VARCHAR(50) NULL DEFAULT NULL,
`lastname` VARCHAR(50) NULL DEFAULT NULL,
`birth_date` DATE NULL DEFAULT NULL,
`cell_phone` VARCHAR(15) NULL DEFAULT NULL,
`department_id` BIGINT(20) NULL DEFAULT NULL,
PRIMARY KEY (`employee_id`),
INDEX `FK_DEPT` (`department_id`),
CONSTRAINT `FK_DEPT` FOREIGN KEY (`department_id`) REFERENCES `department` (`department_id`)
)
COLLATE='latin1_swedish_ci'
ENGINE=InnoDB
ROW_FORMAT=DEFAULT
2。Hibernate的Maven的依赖关系
我们正在使用Maven的依赖管理。复制后,在pom.xml。
文件:pom.xml的
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>net.viralpatel.hibernate</groupId>
<artifactId>HibernateHelloWorldXML</artifactId>
<packaging>jar</packaging>
<version>1.0-SNAPSHOT</version>
<name>HibernateHelloWorldXML</name>
<url>http://maven.apache.org</url>
<dependencies>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.10</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate</artifactId>
<version>3.2.6.ga</version>
</dependency>
</dependencies>
</project>
3。Hibernate的模型类
员工和部门创建模型类映射到相应的数据库表。
文件“:Department.java”
package net.viralpatel.hibernate;
import java.util.Set;
public class Department {
private Long departmentId;
private String departmentName;
private Set<Employee> employees;
// Getter and Setter methods
}
文件“:Employee.java”
package net.viralpatel.hibernate;
import java.sql.Date;
public class Employee {
private Long employeeId;
private String firstname;
private String lastname;
private Date birthDate;
private String cellphone;
private Department department;
public Employee() {
}
public Employee(String firstname, String lastname, Date birthdate,
String phone) {
this.firstname = firstname;
this.lastname = lastname;
this.birthDate = birthdate;
this.cellphone = phone;
}
// Getter and Setter methods
}
4。Hibernate工具类
要访问Hibernate的API,我们将创建一个包装器实用工具类,它为我们提供了SessionFactory的。
文件“:HibernateUtil.java”
package net.viralpatel.hibernate;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
public class HibernateUtil {
private static final SessionFactory sessionFactory = buildSessionFactory();
private static SessionFactory buildSessionFactory() {
try {
// Create the SessionFactory from hibernate.cfg.xml
return new Configuration().configure().buildSessionFactory();
} catch (Throwable ex) {
System.err.println("Initial SessionFactory creation failed." + ex);
throw new ExceptionInInitializerError(ex);
}
}
public static SessionFactory getSessionFactory() {
return sessionFactory;
}
}
5。Hibernate映射XML(HBM)
以下是为每个enitity员工和部门的Hibernate映射文件。
文件“:Employee.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 package="net.viralpatel.hibernate">
<class name="Employee" table="EMPLOYEE">
<id name="employeeId" column="EMPLOYEE_ID">
<generator class="native" />
</id>
<property name="firstname" />
<property name="lastname" column="lastname" />
<property name="birthDate" type="date" column="birth_date" />
<property name="cellphone" column="cell_phone" />
<many-to-one name="department" class="net.viralpatel.hibernate.Department" fetch="select">
<column name="department_id" not-null="true" />
</many-to-one>
</class>
</hibernate-mapping>
文件“: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 package="net.viralpatel.hibernate">
<class name="Department" table="DEPARTMENT">
<id name="departmentId" type="java.lang.Long" column="DEPARTMENT_ID" >
<generator class="native" />
</id>
<property name="departmentName" column="DEPT_NAME"/>
<set name="employees" table="employee"
inverse="true" lazy="true" fetch="select">
<key>
<column name="department_id" not-null="true" />
</key>
<one-to-many class="net.viralpatel.hibernate.Employee" />
</set>
</class>
</hibernate-mapping>
6。审查项目结构
请注意,我们已经使用SET映射与各部门的员工。一个<SET>不同之处在于,它可以只存储唯一的对象。这意味着没有重复的元素可以包含在一组。当您添加第二次一套相同的元素,它将会取代旧的。一组是无序的,但默认情况下,我们可以要求它进行排序。在Java中的一个<SET>的相应类型的java.util.Set映射。
执行<SET>的例子
文件:Main.java文件
package net.viralpatel.hibernate;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
public class Main {
public static void main(String[] args) {
SessionFactory sf = HibernateUtil.getSessionFactory();
Session session = sf.openSession();
session.beginTransaction();
Department department = new Department();
department.setDepartmentName("Sales");
session.save(department);
Employee emp1 = new Employee("Nina", "Mayers", "1212");
Employee emp2 = new Employee("Tony", "Almeida", "4343");
emp1.setDepartment(department);
emp2.setDepartment(department);
session.save(emp1);
session.save(emp2);
session.getTransaction().commit();
session.close();
}
}
输出:
Hibernate: insert into DEPARTMENT (DEPT_NAME) values (?)
Hibernate: insert into EMPLOYEE (firstname, lastname, birth_date, cell_phone, department_id) values (?, ?, ?, ?, ?)
Hibernate: insert into EMPLOYEE (firstname, lastname, birth_date, cell_phone, department_id) values (?, ?, ?, ?, ?)
7。到许多<bag>的例子
在一个<bag>是一个无序的集合,它可以包含重复的元素。这意味着,如果你坚持一个袋子一些元素的顺序,你不能指望以相同的顺序检索集合时保留。没有一个“œbagâ在Java集合框架的概念,所以我们只需使用一个的java.util.List的相对应的一个<bag>。
为了实现包在一个一对多的映射示例中,我们将做以下修改:
7.1更新处模型类
文件“:Department.java”
package net.viralpatel.hibernate;
import java.util.ArrayList;
import java.util.List;
public class Department {
private Long departmentId;
private String departmentName;
private List<Employee> employees;
// Getter and Setter methods
}
7.2更新XML映射
文件“: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 package="net.viralpatel.hibernate">
<class name="Department" table="DEPARTMENT">
<id name="departmentId" type="java.lang.Long" column="DEPARTMENT_ID" >
<generator class="native" />
</id>
<property name="departmentName" column="DEPT_NAME"/>
<bag name="employees" table="employee"
inverse="true" lazy="true" fetch="select">
<key>
<column name="employee_id" not-null="true" />
</key>
<one-to-many class="net.viralpatel.hibernate.Employee" />
</bag>
</class>
</hibernate-mapping>
7.3执行<bag>例如
执行相同的Main.java文件,在上面的例子中,我们创建了。
输出:
Hibernate: insert into DEPARTMENT (DEPT_NAME) values (?)
Hibernate: insert into EMPLOYEE (firstname, lastname, birth_date, cell_phone, department_id) values (?, ?, ?, ?, ?)
Hibernate: insert into EMPLOYEE (firstname, lastname, birth_date, cell_phone, department_id) values (?, ?, ?, ?, ?)
8。到许多<LIST>例如
使用<list>是一个索引集合的索引也将被保存。这意味着我们可以保留时,检索列表中的顺序。,它不同于<bag>为持续的元素的指数而<bag>不不。在Java中使用<list>相应类型的java.util.List的。
为了实现我们的一个一对多的映射示例列表中,我们将做如下变化:
8.1添加索引列的雇员表
DROP TABLE if exists `employee`;
CREATE TABLE `employee` (
`employee_id` BIGINT(10) NOT NULL AUTO_INCREMENT,
`firstname` VARCHAR(50) NULL DEFAULT NULL,
`lastname` VARCHAR(50) NULL DEFAULT NULL,
`birth_date` DATE NULL DEFAULT NULL,
`cell_phone` VARCHAR(15) NULL DEFAULT NULL,
`department_id` BIGINT(20) NULL DEFAULT NULL,
`idx` INT(11) NOT NULL DEFAULT '0',
PRIMARY KEY (`employee_id`),
INDEX `FK_DEPT` (`department_id`),
CONSTRAINT `FK_DEPT` FOREIGN KEY (`department_id`) REFERENCES `department` (`department_id`)
)
COLLATE='latin1_swedish_ci'
ENGINE=InnoDB
ROW_FORMAT=DEFAULT
请注意,在我们现有的employee表中,我们添加了一个新列“idxâ存储每个记录的索引值。
8.2更新模型对象
文件“:Department.java”
package net.viralpatel.hibernate;
import java.util.List;
public class Department {
private Long departmentId;
private String departmentName;
private List<Employee> employees;
// Getter and Setter methods
}
8.3更新XML映射
文件“: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 package="net.viralpatel.hibernate">
<class name="Department" table="DEPARTMENT">
<id name="departmentId" type="java.lang.Long" column="DEPARTMENT_ID">
<generator class="native" />
</id>
<property name="departmentName" column="DEPT_NAME"/>
<list name="employees" table="employee"
inverse="false" cascade="all">
<key column="department_id" />
<list-index column="idx" />
<one-to-many class="net.viralpatel.hibernate.Employee" />
</list>
</class>
</hibernate-mapping>
在上面的Hibernate映射XML文件,注意,我们已经加入列表标签映射与各部门的员工列表。一个新的索引列“œidxâ是指将存储记录的索引。需要注意的是逆=“€falseâ中指定的映射,这使得作为关系雇主署。因此,时部保存对象时,它会自动保存雇员。这是必需的,这样的部门可以管理员工的索引值。DEPARTMENT_ID键列。
8.4执行<LIST>例如
输出:
Hibernate: insert into DEPARTMENT (DEPT_NAME) values (?)
Hibernate: insert into EMPLOYEE (firstname, lastname, birth_date, cell_phone) values (?, ?, ?, ?)
Hibernate: insert into EMPLOYEE (firstname, lastname, birth_date, cell_phone) values (?, ?, ?, ?)
Hibernate: update EMPLOYEE set department_id=?, idx=? where EMPLOYEE_ID=?
Hibernate: update EMPLOYEE set department_id=?, idx=? where EMPLOYEE_ID=?
9。到许多<array>的例子
一个<array>有相同的用法除了作为<LIST>的对应于Java中的数组类型,而不是一个java.util.List。这是很少使用,除非我们为传统应用程序映射。在大多数情况下,我们应该使用<LIST>。这是因为一个数组的大小不能被增加或减少动态的,在那里作为一个列表。
实现数组中的一个一对多的映射示例中,我们将做以下修改:
9.1更新模型对象
文件“:Department.java”
package net.viralpatel.hibernate;
public class Department {
private Long departmentId;
private String departmentName;
private Employee[] employees;
// Getter and Setter methods
}
我们简单地改变员工名单的员工[]数组。
9.2更新XML映射
文件“: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 package="net.viralpatel.hibernate">
<class name="Department" table="DEPARTMENT">
<id name="departmentId" type="java.lang.Long" column="DEPARTMENT_ID">
<generator class="native" />
</id>
<property name="departmentName" column="DEPT_NAME"/>
<array name="employees" table="employee"
inverse="false" cascade="all">
<key column="department_id" />
<list-index column="idx" />
<one-to-many class="net.viralpatel.hibernate.Employee" />
</array>
</class>
</hibernate-mapping>
9.2执行<array>的例子
执行相同的Main.java类,我们创建了,在上述<LIST>例如,。
输出:
Hibernate: insert into DEPARTMENT (DEPT_NAME) values (?)
Hibernate: insert into EMPLOYEE (firstname, lastname, birth_date, cell_phone) values (?, ?, ?, ?)
Hibernate: insert into EMPLOYEE (firstname, lastname, birth_date, cell_phone) values (?, ?, ?, ?)
Hibernate: update EMPLOYEE set department_id=?, idx=? where EMPLOYEE_ID=?
Hibernate: update EMPLOYEE set department_id=?, idx=? where EMPLOYEE_ID=?
如果你有兴趣可以阅读:Hibernate的一对一映射教程 或更多相关教程: http://www.software8.co/wzjs/PHPshili/