第九章 关系映射 组件关联映射

组件是针对同一张表中的字段进行映射,作用是将字段多的一张表分成多个实体类来表示。

如：name与user

user表中有first_name及last_name。在实体类中，自定义一个Name类来表示first_name与last_name;

Name实体类：

package cn.framelife.mvc.entity;

public class Name {
	private String firstName;
	private String lastName;

	public String getFirstName() {
		return firstName;
	}

	public void setFirstName(String firstName) {
		this.firstName = firstName;
	}

	public String getLastName() {
		return lastName;
	}

	public void setLastName(String lastName) {
		this.lastName = lastName;
	}

}

User实体类：

package cn.framelife.mvc.entity;

import java.io.Serializable;

public class User implements Serializable {
	private Integer id;
	private Name name;

	public Integer getId() {
		return id;
	}

	public void setId(Integer id) {
		this.id = id;
	}

	public Name getName() {
		return name;
	}

	public void setName(Name name) {
		this.name = name;
	}
}

User.hbm.xml:

<hibernate-mapping>
    <class name="cn.framelife.hibernate.entity.User" table="user" catalog="hibernate">
        <id name="id" type="java.lang.Integer">
            <column name="id" />
            <generator class="native" />
        </id>
        <component name="name" class="cn.framelife.hibernate.entity.Name">
        	<property name="firstName" column="first_name"></property>
        	<property name="lastName" column="last_name"></property>
        </component>
    </class>
</hibernate-mapping>

增加操作：

tx = session.beginTransaction();
			Name name = new Name();
			name.setFirstName("111");
			name.setLastName("2222");

			User user = new User();
			user.setName(name);
			session.save(user);

			tx.commit();