Hibernate的一对多XML映射教程
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" /&g
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