注意事項(xiàng)：
1.單向一對(duì)多
只需在“一”放進(jìn)行配置
2.雙向一對(duì)多
需要在關(guān)聯(lián)雙方都加以配置，而且需要在一的一方設(shè)置inverse=true
首先是實(shí)體類：
TAddress.java（多的一方）
public class TAddress implements Serializable {
private static final long serialVersionUID = 1121137857691229229L;
private Integer id;
private String address;
private String zipcode;
private String tel;
private String type;
private TUser user; //必須有
............
}
TUser.java（一的一方）
public class TUser implements Serializable {
private static final long serialVersionUID = 1224691192698621789L;
private Integer id;
private Integer age;
private String name;
@SuppressWarnings("rawtypes")
private Set address = new HashSet(); //多的一方放在集合中
....................
}
然后是各個(gè)實(shí)體類的配置文件
TAddress.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd" >
<!-- 一對(duì)多 -->
<hibernate-mapping>
<class name="com.model.TAddress" table="t_address"
dynamic-update="false" dynamic-insert="false">
<id name="id" type="java.lang.Integer" column="id" unsaved-value="0">
<generator class="native" />
</id>
<property name="address" column="address" type="string" />
<property name="tel" column="tel" type="string" />
<property name="zipcode" column="zipcode" type="string" />
<property name="type" column="type" type="string" />
<!-- 必須有many-to-one 否則關(guān)聯(lián)字段（user_id）為null -->
<many-to-one name="user"
class="com.model.TUser"
cascade="none"
outer-join="auto"
update="true"
insert="true"
access="property"
column="user_id"
not-null="true">
</many-to-one>
</class>
</hibernate-mapping>
TUser.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd" >
<!-- 一對(duì)多 外鍵關(guān)聯(lián) -->
<!-- Select from TUser where id=1 Select from TUser where id=1 to Select
from TUser where id=1 or id=2 -->
<!-- batch-size 批量加載機(jī)制 可以自定義每次批量加載的數(shù)量 -->
<hibernate-mapping>
<class name="com.model.TUser" table="t_user" dynamic-update="true"
>
<id name="id" type="java.lang.Integer" column="id" unsaved-value="0">
<generator class="native" />
</id>
<property name="name" column="name" />
<property name="age" column="age" />
<set name="address" table="t_address" cascade="all" order-by="zipcode asc"
lazy="true" inverse="true">
<key column="user_id" /><!-- 確定關(guān)聯(lián)的外鍵列 -->
<one-to-many class="com.model.TAddress" />
</set>
</class>
</hibernate-mapping>
其次是hibernate.cfg.xml
<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-2.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- properties -->
<!-- 數(shù)據(jù)庫(kù)URL -->
<property name="hibernate.connection.url">jdbc:mysql://localhost/onetomany</property>
<!-- 數(shù)據(jù)庫(kù)JDBC驅(qū)動(dòng) -->
<property name="hibernate.connection.driver_class">org.gjt.mm.mysql.Driver</property>
<!-- 數(shù)據(jù)庫(kù)用戶名 -->
<property name="hibernate.connection.username">root</property>
<!-- 數(shù)據(jù)庫(kù)密碼 -->
<property name="hibernate.connection.password">hello</property>
<!-- 數(shù)據(jù)庫(kù)方言 -->
<property name="dialect">net.sf.hibernate.dialect.MySQLDialect</property>
<!-- 是否日志調(diào)試 -->
<property name="show_sql">true</property>
<!-- 是否使用數(shù)據(jù)庫(kù)外連接 -->
<property name="use_outer_join">true</property>
<!-- 事務(wù)管理 使用JDBC Transaction（使用JTA會(huì)報(bào)錯(cuò)） -->
<property name="transaction.factory_class">
net.sf.hibernate.transaction.JDBCTransactionFactory
</property>
<!-- 指定hibernate每次提交的SQL數(shù)量 對(duì)批量操作的性能提升幫助很大！！！！！！！！！！！！！ -->
<property name="hibernate.jdbc.batch_size">25</property>
<!-- 映射文件配置，配置文件名必須包含其相對(duì)于根的全路徑 -->
<mapping resource="com/model/TUser.hbm.xml" />
<mapping resource="com/model/TAddress.hbm.xml" />
</session-factory>
</hibernate-configuration>
測(cè)試代碼（部分）
增加
public void testSave(){
try {
Transaction tx=session.beginTransaction();
// TUser user=(TUser) session.load(TUser.class, 1);
TUser user=new TUser();
user.setName("zhangsan");
user.setAge(20);
TAddress address=new TAddress();
address.setAddress("jingsan");
address.setTel("1361380");
address.setZipcode("45000");
address.setType("java");
address.setUser(user); //設(shè)置關(guān)聯(lián)的TUser對(duì)象
user.getAddress().add(address);
session.save(user); //級(jí)聯(lián)更新
tx.commit();
} catch (HibernateException e) {
e.printStackTrace();
}
}
查詢
public void testLoad(){
try {
Transaction tx=session.beginTransaction();
String hql="from TUser where name='zhangsan'";
List list=session.createQuery(hql).list();
System.out.println("-------------1------------");
Iterator iter=list.iterator();
while(iter.hasNext()){
TUser user=(TUser) iter.next();
System.out.println("--------------2------------");
System.out.println("user.name="+user.getName());
System.out.println("--------------3------------");
System.out.println("user.address="+user.getAddress().size());
System.out.println("--------------4------------");
}
} catch (HibernateException e) {
e.printStackTrace();
}
}
批量插入（可以提高性能）
實(shí)現(xiàn)機(jī)制：如果使用了批量加載機(jī)制，hibernate在進(jìn)行數(shù)據(jù)查詢操作前，會(huì)自動(dòng)在當(dāng)前session中尋找是否還存在
其他同類型待加載的數(shù)據(jù)，如果有，則將其查詢條件合并在當(dāng)前的select語句中一并提交，這樣，通過
一次數(shù)據(jù)庫(kù)操作即完成了多個(gè)讀取任務(wù)。
//批量插入操作性能優(yōu)化 通過配置<property name="hibernate.jdbc.batch_size">25</property>
public void testBatchInsert(){
long start=System.currentTimeMillis();
this.importUserList();
long end=System.currentTimeMillis();
System.out.println("批量插入花費(fèi)時(shí)間是"+(end-start));
}
public void importUserList(){
try {
Transaction tx=session.beginTransaction();
for(int i=0;i<10000;i++){
TUser user=new TUser();
user.setName("user"+i);
session.save(user);
if(i%25==0){ //以每25個(gè)數(shù)據(jù)作為一個(gè)處理單元
session.flush();
session.clear();
}
}
tx.commit();
} catch (HibernateException e) {
e.printStackTrace();
}
}