hibernate之多对一。在多对一中,在多的一方设置many-to-one,而在一的一方不设置。
1、新建一个java项目hibernate,新建类Employee.java与Department.java
Employee.java
package cn.ehoo.hibernate.domain;
/**
*@author whp
*@Email whp@ehoo.cn
*@Nov 11, 2010
*
*/
public class Employee {
private Long id;
private String name;
private Department depart;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Department getDepart() {
return depart;
}
public void setDepart(Department depart) {
this.depart = depart;
}
}
Employee.java的配置文件Employee.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="cn.ehoo.hibernate.domain" >
<class name="Employee" table="employee" dynamic-update="true" >
<id name="id" type="long">
<generator class="native" />
</id>
<property name="name" />
<many-to-one name="depart" column="depart_id" cascade="save-update"/>
</class>
</hibernate-mapping>
Department.java
package cn.ehoo.hibernate.domain;
/**
*@author whp
*@Email whp@ehoo.cn
*@Nov 11, 2010
*
*/
public class Department {
private Long id;
private String name;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
Department.java的配置文件Department.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="cn.ehoo.hibernate.domain">
<class name="Department" table="department" >
<id name="id" type="long">
<generator class="native" />
</id>
<property name="name" />
</class>
</hibernate-mapping>
2、新建类Many2One.java
package cn.ehoo.hibernate;
import org.hibernate.Session;
import org.hibernate.Transaction;
import cn.ehoo.hibernate.domain.Department;
import cn.ehoo.hibernate.domain.Employee;
/**
* @author whp
* @Email whp@ehoo.cn
* @Nov 11, 2010
*
*/
public class Many2One {
public static void main(String[] args) {
Session s = null;
Transaction tr = null;
s = HibernateUtil.getCurrentSession();
tr = s.beginTransaction();
tr.begin();
/*Department dep = (Department) s.load(Department.class, 1L);
dep.setName("department_1");
Employee em = new Employee();
em.setName("employee_2");
em.setDepart(dep);
s.save(em);*/
Department dep = (Department) s.load(Department.class, 1L);
Employee em = (Employee)s.load(Employee.class, 1L);
em.setName("whp1");
em.setDepart(dep);
s.update(em);
tr.commit();
}
}
3、hibernate.cfg.xml文件的配置
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql:///test</property>
<property name="connection.username">root</property>
<property name="connection.password">123</property>
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="current_session_context_class">thread</property>
<property name="hbm2ddl.auto">update</property>
<property name="show_sql">true</property>
<property name="format_sql">true</property>
<property name="generate_statistics">true</property>
<mapping resource="cn/ehoo/hibernate/domain/Department.hbm.xml" />
<mapping resource="cn/ehoo/hibernate/domain/Employee.hbm.xml" />
</session-factory>
</hibernate-configuration>
hibernate之一对多。在一对多中,在多的一方不设置many-to-one,而在一的一方设置one-to-many。
1、新建一个java项目hibernate,新建类Employee.java与Department.java
Employee.java
package cn.ehoo.hibernate.domain;
/**
*@author whp
*@Email whp@ehoo.cn
*@Nov 11, 2010
*
*/
public class Employee {
private Long id;
private String name;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
Employee.java的配置文件Employee.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="cn.ehoo.hibernate.domain" >
<class name="Employee" table="employee" dynamic-update="true" >
<id name="id" type="long">
<generator class="native" />
</id>
<property name="name" />
</class>
</hibernate-mapping>
Department.java
package cn.ehoo.hibernate.domain;
import java.util.HashSet;
import java.util.Set;
/**
*@author whp
*@Email whp@ehoo.cn
*@Nov 11, 2010
*
*/
public class Department {
private Long id;
private String name;
private Set<Employee> emps = new HashSet<Employee>();
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Set<Employee> getEmps() {
return emps;
}
public void setEmps(Set<Employee> emps) {
this.emps = emps;
}
}
Department.java的配置文件Department.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="cn.ehoo.hibernate.domain">
<class name="Department" table="department" >
<id name="id" type="long">
<generator class="native" />
</id>
<property name="name" />
<set name="emps" cascade="save-update">
<key column="depart_id" />
<one-to-many class="Employee" />
</set>
</class>
</hibernate-mapping>
2、新建类One2Many.java
package cn.ehoo.hibernate;
import org.hibernate.Session;
import org.hibernate.Transaction;
import cn.ehoo.hibernate.domain.Department;
import cn.ehoo.hibernate.domain.Employee;
/**
* @author whp
* @Email whp@ehoo.cn
* @Nov 11, 2010
*
*/
public class One2Many {
public static void main(String[] args) {
Session s = null;
Transaction tr = null;
s = HibernateUtil.getCurrentSession();
tr = s.beginTransaction();
tr.begin();
Department dep = new Department();
dep.setName("department_1");
Employee em = new Employee();
em.setName("employee_2");
dep.getEmps().add(em);
s.save(dep);
tr.commit();
}
}
3、hibernate.cfg.xml文件的配置
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql:///test</property>
<property name="connection.username">root</property>
<property name="connection.password">123</property>
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="current_session_context_class">thread</property>
<property name="hbm2ddl.auto">update</property>
<property name="show_sql">true</property>
<property name="format_sql">true</property>
<property name="generate_statistics">true</property>
<mapping resource="cn/ehoo/hibernate/domain/Department.hbm.xml" />
<mapping resource="cn/ehoo/hibernate/domain/Employee.hbm.xml" />
</session-factory>
</hibernate-configuration>
hibernate之一对多双向关联。在一的一方要配置one-to-many,在多的一方要配置many-to-one。在一对多双向关联时,一般要把一一方的集合中设置inverse=true,这样可以让一的一方来放弃关系的维护,从而节省资源。
1、新建一个java项目hibernate,新建类Employee.java与Department.java
Employee.java
package cn.ehoo.hibernate.domain;
/**
*@author whp
*@Email whp@ehoo.cn
*@Nov 11, 2010
*
*/
public class Employee {
private Long id;
private String name;
private Department depart;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Department getDepart() {
return depart;
}
public void setDepart(Department depart) {
this.depart = depart;
}
}
Employee.java的配置文件Employee.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="cn.ehoo.hibernate.domain" >
<class name="Employee" table="employee" dynamic-update="true" >
<id name="id" type="long">
<generator class="native" />
</id>
<property name="name" />
<many-to-one name="depart" column="depart_id" cascade="save-update"/>
</class>
</hibernate-mapping>
Department.java
package cn.ehoo.hibernate.domain;
import java.util.HashSet;
import java.util.Set;
/**
*@author whp
*@Email whp@ehoo.cn
*@Nov 11, 2010
*
*/
public class Department {
private Long id;
private String name;
private Set<Employee> emps = new HashSet<Employee>();
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Set<Employee> getEmps() {
return emps;
}
public void setEmps(Set<Employee> emps) {
this.emps = emps;
}
}
Department.java的配置文件Department.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="cn.ehoo.hibernate.domain">
<class name="Department" table="department" >
<id name="id" type="long">
<generator class="native" />
</id>
<property name="name" />
<set name="emps" cascade="save-update">
<key column="depart_id" />
<one-to-many class="Employee" />
</set>
</class>
</hibernate-mapping>
2、新建类One2Many.java
package cn.ehoo.hibernate;
import org.hibernate.Session;
import org.hibernate.Transaction;
import cn.ehoo.hibernate.domain.Department;
import cn.ehoo.hibernate.domain.Employee;
/**
* @author whp
* @Email whp@ehoo.cn
* @Nov 11, 2010
*
*/
public class One2Many {
public static void main(String[] args) {
Session s = null;
Transaction tr = null;
s = HibernateUtil.getCurrentSession();
tr = s.beginTransaction();
tr.begin();
Department dep = new Department();
dep.setName("department_1");
Employee em = new Employee();
em.setName("employee_2");
dep.getEmps().add(em);
s.save(dep);
tr.commit();
}
}
3、hibernate.cfg.xml文件的配置
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql:///test</property>
<property name="connection.username">root</property>
<property name="connection.password">123</property>
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="current_session_context_class">thread</property>
<property name="hbm2ddl.auto">update</property>
<property name="show_sql">true</property>
<property name="format_sql">true</property>
<property name="generate_statistics">true</property>
<mapping resource="cn/ehoo/hibernate/domain/Department.hbm.xml" />
<mapping resource="cn/ehoo/hibernate/domain/Employee.hbm.xml" />
</session-factory>
</hibernate-configuration>
casecade为级联。inverse为关联。inverse设置为true是放弃关系的维护,一般在双向关联里使用。并且只有集合一端才有。而casecode在一的一端与多的一端里都会存在