Hibernate的学习之路十九（一对多的JavaBean编写和映射的配置文件的编写）

前言

     Hibernate属于ORM框架，它基本不适用sql语句，但是设计到多表查询的时候，就有些麻烦了。
     当一对多的时候，一是集合，多是对象。
     一里是多的对象集合，多里是一的对象。

分析

以下是一的JavaBean代码，记住千万不要new。Hibernate会通过映射自动实例化，如果new了，那么一直都是一个对象，会出问题。

package com.itheima.domain;

/**
* 客户的联系人
* 多方
* @author Administrator
*/
public class Linkman {

private Long lkm_id;
private String lkm_name;
private String lkm_gender;
private String lkm_phone;
private String lkm_mobile;
private String lkm_email;
private String lkm_qq;
private String lkm_position;
private String lkm_memo;

// 编写一个对象，不要自己new
private Customer customer;

public Long getLkm_id() {
return lkm_id;
}
public void setLkm_id(Long lkm_id) {
this.lkm_id = lkm_id;
}
public String getLkm_name() {
return lkm_name;
}
public void setLkm_name(String lkm_name) {
this.lkm_name = lkm_name;
}
public String getLkm_gender() {
return lkm_gender;
}
public void setLkm_gender(String lkm_gender) {
this.lkm_gender = lkm_gender;
}
public String getLkm_phone() {
return lkm_phone;
}
public void setLkm_phone(String lkm_phone) {
this.lkm_phone = lkm_phone;
}
public String getLkm_mobile() {
return lkm_mobile;
}
public void setLkm_mobile(String lkm_mobile) {
this.lkm_mobile = lkm_mobile;
}
public String getLkm_email() {
return lkm_email;
}
public void setLkm_email(String lkm_email) {
this.lkm_email = lkm_email;
}
public String getLkm_qq() {
return lkm_qq;
}
public void setLkm_qq(String lkm_qq) {
this.lkm_qq = lkm_qq;
}
public String getLkm_position() {
return lkm_position;
}
public void setLkm_position(String lkm_position) {
this.lkm_position = lkm_position;
}
public String getLkm_memo() {
return lkm_memo;
}
public void setLkm_memo(String lkm_memo) {
this.lkm_memo = lkm_memo;
}
public Customer getCustomer() {
return customer;
}
public void setCustomer(Customer customer) {
this.customer = customer;
}

}

以下是一的配置文件
其中name值是javabean里的参数名。
其中class值是对象的路径。
其中clumn值是外键值。

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>

<class name="com.itheima.domain.Linkman" table="cst_linkman">
<id name="lkm_id" column="lkm_id">
<generator class="native"/>
</id>

<property name="lkm_name" column="lkm_name"/>
<property name="lkm_gender" column="lkm_gender"/>
<property name="lkm_phone" column="lkm_phone"/>
<property name="lkm_mobile" column="lkm_mobile"/>
<property name="lkm_email" column="lkm_email"/>
<property name="lkm_qq" column="lkm_qq"/>
<property name="lkm_position" column="lkm_position"/>
<property name="lkm_memo" column="lkm_memo"/>

<!-- 先配置多方
name	当前JavaBean中的属性
class	属性的全路径
column	外键的字段
-->
<many-to-one name="customer" class="com.itheima.domain.Customer" column="lkm_cust_id" cascade="save-update"/>

</class>

</hibernate-mapping>

以下是多的javabean，默认记得用set的集合。

package com.itheima.domain;

import java.util.HashSet;
import java.util.Set;

/**
* 客户的JavaBean
* 一方
* @author Administrator
*/
public class Customer {

private Long cust_id;
private String cust_name;
private Long cust_user_id;
private Long cust_create_id;
private String cust_source;
private String cust_industry;
private String cust_level;
private String cust_linkman;
private String cust_phone;
private String cust_mobile;

// Hibernate框架默认的集合是set集合，集合必须要自己手动的初始化
private Set<Linkman> linkmans = new HashSet<Linkman>();

public Long getCust_id() {
return cust_id;
}
public void setCust_id(Long cust_id) {
this.cust_id = cust_id;
}
public String getCust_name() {
return cust_name;
}
public void setCus
ba87
t_name(String cust_name) {
this.cust_name = cust_name;
}
public Long getCust_user_id() {
return cust_user_id;
}
public void setCust_user_id(Long cust_user_id) {
this.cust_user_id = cust_user_id;
}
public Long getCust_create_id() {
return cust_create_id;
}
public void setCust_create_id(Long cust_create_id) {
this.cust_create_id = cust_create_id;
}
public String getCust_source() {
return cust_source;
}
public void setCust_source(String cust_source) {
this.cust_source = cust_source;
}
public String getCust_industry() {
return cust_industry;
}
public void setCust_industry(String cust_industry) {
this.cust_industry = cust_industry;
}
public String getCust_level() {
return cust_level;
}
public void setCust_level(String cust_level) {
this.cust_level = cust_level;
}
public String getCust_linkman() {
return cust_linkman;
}
public void setCust_linkman(String cust_linkman) {
this.cust_linkman = cust_linkman;
}
public String getCust_phone() {
return cust_phone;
}
public void setCust_phone(String cust_phone) {
this.cust_phone = cust_phone;
}
public String getCust_mobile() {
return cust_mobile;
}
public void setCust_mobile(String cust_mobile) {
this.cust_mobile = cust_mobile;
}
public Set<Linkman> getLinkmans() {
return linkmans;
}
public void setLinkmans(Set<Linkman> linkmans) {
this.linkmans = linkmans;
}

}

以下是多的配置文件
其中的name是javabean中集合参数的名称。
其中cloumn是数据库中外建的字段。
其中的class是集合对象泛型的路径。

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>

<class name="com.itheima.domain.Customer" table="cst_customer">
<id name="cust_id" column="cust_id">
<generator class="native"/>
</id>

<property name="cust_name" column="cust_name"/>
<property name="cust_user_id" column="cust_user_id"/>
<property name="cust_create_id" column="cust_create_id"/>
<property name="cust_source" column="cust_source"/>
<property name="cust_industry" column="cust_industry"/>
<property name="cust_level" column="cust_level"/>
<property name="cust_linkman" column="cust_linkman"/>
<property name="cust_phone" column="cust_phone"/>
<property name="cust_mobile" column="cust_mobile"/>

<!-- 配置一方 -->
<!--
set标签name属性：表示集合的名称
-->
<set name="linkmans" inverse="true">
<!-- 需要出现子标签 -->
<!-- 外键的字段 -->
<key column="lkm_cust_id"/>
<one-to-many class="com.itheima.domain.Linkman"/>
</set>

</class>

</hibernate-mapping>