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)
2017-12-03 12:36
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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>
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