在使用map集合配置实体类型时候,其key为某一个字段,而value是这一个实体的实例
比如Team和Student一对多的关系,Team中有一个ma存放student,这个map的key为student中的cardid,而value是具体的一个student实例
需要注意的是,这样使用时候,team端需要维护cardid,所以,不能再像set那样可以在1端设置inverse="true"来提高性能
数据库结构:
create
table
teamMapC (id
varchar
(
32
),teamname
varchar
(
32
));
create table studentMapC (id varchar ( 32 ),cardid varchar ( 32 ),name varchar ( 32 ),age int ,description varchar ( 32 ), team_id varchar ( 32 ));
create table studentMapC (id varchar ( 32 ),cardid varchar ( 32 ),name varchar ( 32 ),age int ,description varchar ( 32 ), team_id varchar ( 32 ));
实体类:
package
Collection.Map.Complex;
public class Student {
private String id;
private String name;
private String description;
private int age;
private String cardid;
private Team team;
public String getId() {
return id;
}
public void setId(String id) {
this .id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this .name = name;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this .description = description;
}
public int getAge() {
return age;
}
public void setAge( int age) {
this .age = age;
}
public String getCardid() {
return cardid;
}
public void setCardid(String cardid) {
this .cardid = cardid;
}
public Team getTeam() {
return team;
}
public void setTeam(Team team) {
this .team = team;
}
}
package Collection.Map.Complex;
import java.util.HashMap;
import java.util.Map;
public class Team {
private String id;
private String teamname;
private Map students = new HashMap();
public String getId() {
return id;
}
public void setId(String id) {
this .id = id;
}
public String getTeamname() {
return teamname;
}
public void setTeamname(String teamname) {
this .teamname = teamname;
}
public Map getStudents() {
return students;
}
public void setStudents(Map students) {
this .students = students;
}
}
public class Student {
private String id;
private String name;
private String description;
private int age;
private String cardid;
private Team team;
public String getId() {
return id;
}
public void setId(String id) {
this .id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this .name = name;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this .description = description;
}
public int getAge() {
return age;
}
public void setAge( int age) {
this .age = age;
}
public String getCardid() {
return cardid;
}
public void setCardid(String cardid) {
this .cardid = cardid;
}
public Team getTeam() {
return team;
}
public void setTeam(Team team) {
this .team = team;
}
}
package Collection.Map.Complex;
import java.util.HashMap;
import java.util.Map;
public class Team {
private String id;
private String teamname;
private Map students = new HashMap();
public String getId() {
return id;
}
public void setId(String id) {
this .id = id;
}
public String getTeamname() {
return teamname;
}
public void setTeamname(String teamname) {
this .teamname = teamname;
}
public Map getStudents() {
return students;
}
public void setStudents(Map students) {
this .students = students;
}
}
Hibernate.cfg.xml
<?
xml version='1.0' encoding='UTF-8'
?>
<! DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd" >
<!-- Generated by MyEclipse Hibernate Tools. -->
< hibernate-configuration >
< session-factory >
< property name ="connection.username" > root </ property >
< property name ="connection.url" >
jdbc:mysql://localhost:3306/schoolproject?characterEncoding=gb2312 & useUnicode=true
</ property >
< property name ="dialect" >
org.hibernate.dialect.MySQLDialect
</ property >
< property name ="myeclipse.connection.profile" > mysql </ property >
< property name ="connection.password" > 1234 </ property >
< property name ="connection.driver_class" >
com.mysql.jdbc.Driver
</ property >
< property name ="hibernate.dialect" >
org.hibernate.dialect.MySQLDialect
</ property >
< property name ="hibernate.show_sql" > true </ property >
< property name ="current_session_context_class" > thread </ property >
< property name ="jdbc.batch_size" > 15 </ property >
< mapping resource ="Collection/Map/Complex/Student.hbm.xml" />
< mapping resource ="Collection/Map/Complex/Team.hbm.xml" />
</ session-factory >
</ hibernate-configuration >
<! DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd" >
<!-- Generated by MyEclipse Hibernate Tools. -->
< hibernate-configuration >
< session-factory >
< property name ="connection.username" > root </ property >
< property name ="connection.url" >
jdbc:mysql://localhost:3306/schoolproject?characterEncoding=gb2312 & useUnicode=true
</ property >
< property name ="dialect" >
org.hibernate.dialect.MySQLDialect
</ property >
< property name ="myeclipse.connection.profile" > mysql </ property >
< property name ="connection.password" > 1234 </ property >
< property name ="connection.driver_class" >
com.mysql.jdbc.Driver
</ property >
< property name ="hibernate.dialect" >
org.hibernate.dialect.MySQLDialect
</ property >
< property name ="hibernate.show_sql" > true </ property >
< property name ="current_session_context_class" > thread </ property >
< property name ="jdbc.batch_size" > 15 </ property >
< mapping resource ="Collection/Map/Complex/Student.hbm.xml" />
< mapping resource ="Collection/Map/Complex/Team.hbm.xml" />
</ session-factory >
</ hibernate-configuration >
Team.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" >
<!--
Mapping file autogenerated by MyEclipse - Hibernate Tools
-->
< hibernate-mapping >
< class name ="Collection.Map.Complex.Team" table ="teamMapC" >
< id name ="id" unsaved-value ="null" >
< generator class ="uuid.hex" ></ generator >
</ id >
< property name ="teamname" type ="string" column ="teamname" ></ property >
<!-- 由于cardid需要team来维护,所以,使用map表示1对多时候,不能再1方设置inverse="true" -->
< map name ="students" table ="studentMap" cascade ="all" >
< key column ="team_id" ></ key >
<!-- index代表key,element(或one-to-many)代表value -->
<!-- 这里用cardid作为key,具体的student实例作为value -->
< index column ="cardid" type ="string" ></ index >
< one-to-many class ="Collection.Map.Complex.Student" />
</ map >
</ class >
</ hibernate-mapping >
<! DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
<!--
Mapping file autogenerated by MyEclipse - Hibernate Tools
-->
< hibernate-mapping >
< class name ="Collection.Map.Complex.Team" table ="teamMapC" >
< id name ="id" unsaved-value ="null" >
< generator class ="uuid.hex" ></ generator >
</ id >
< property name ="teamname" type ="string" column ="teamname" ></ property >
<!-- 由于cardid需要team来维护,所以,使用map表示1对多时候,不能再1方设置inverse="true" -->
< map name ="students" table ="studentMap" cascade ="all" >
< key column ="team_id" ></ key >
<!-- index代表key,element(或one-to-many)代表value -->
<!-- 这里用cardid作为key,具体的student实例作为value -->
< index column ="cardid" type ="string" ></ index >
< one-to-many class ="Collection.Map.Complex.Student" />
</ map >
</ class >
</ hibernate-mapping >
Student.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" >
<!--
Mapping file autogenerated by MyEclipse - Hibernate Tools
-->
< hibernate-mapping >
< class name ="Collection.Map.Complex.Student" table ="studentMapC" >
< id name ="id" unsaved-value ="null" >
< generator class ="uuid.hex" ></ generator >
</ id >
<! DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
<!--
Mapping file autogenerated by MyEclipse - Hibernate Tools
-->
< hibernate-mapping >
< class name ="Collection.Map.Complex.Student" table ="studentMapC" >
< id name ="id" unsaved-value ="null" >
< generator class ="uuid.hex" ></ generator >
</ id >